Mondeo TDCi mk4 limp mode and several DTCs

[Mutti82]

My vehicle is Mondeo 2011 2.0 TDCi 140PS PowerShift. I have had this intermittent problem now for almost 1,5 years. Usually occurs when cold humid weather (spring and autumn when around 0 degrees Celsius). Car suddenly goes into limp mode and gives several DTCs, ones which appear everytime are P062E from PCM, U0401 from 1-3 other control units and some other random codes. Had to stop and restart engine 5-20 times every 20 meters or idle 15min to fault go away. Fault was tracked to PCM and it was changed two months ago.

Car ran fine until this morning. Weather again wet and +5 Celsius. Drove 20m and again limp mode, ESP light lit, engine malfunction and transmission limited function. DTC reader gave same codes and also P1719 which is described engine torque sensor signal, in some forums it is pointed towards transmission fault. When accelerating car was bouncing like gangaroo and of course I had to stop in every f***ing intersection and lights. I recall that over this 1,5 year I have heard and felt randomly metallic hard sound when steering wheel is turned and transmission changes gear (only when changing from 1 -> 2 or 2 -> 3). That sound came also this morning. Though I've heard that sound some times with no limp mode so not directly related to it.

I'm starting to be bit despered with this fault. Wiring harness is also visually checked and electrically tested in Ford dealer (though in warm and dry conditions), no faults found. Transmission mileage service made month ago so no bad oils etc. Anyone has had similar problems? Any suggestion where to continue looking?

Original post of this issue with more about symptoms:

 

[Tdci-Peter]

11 hours ago, Mutti82 said:

Weather again wet and +5 Celsius. Drove 20m and again limp mode, ESP light lit, engine malfunction and transmission limited function. DTC reader gave same codes and also P1719

Hmmm, that pcm was replaced in August, if the last thread was anything to go by. So the electrics may not have had much of a damp test over that time.

With U0401 appearing often, it very much looks like a connector or electronics corrosion & damp problem.

I would have a good look at the replacement pcm, to see if the problem is happening again. Water can travel down wires, so maybe the basic fault still exists. Then the tcm & abs modules could be checked, at least the connectors. Also any connectors in the main fuse box, and in and around the body control module in the car. Any signs of water getting in to the footwells?

If wires do get wet, they can also corrode internally, becoming high resistance.

There are a lot of possibilities, but looking for wet areas, and then following wiring through looking for evidence of corosion may be the best way.

The P062E Bank2 reference may be due to damp. If the pcm has a bank2 capability internally, but is not connected to anything, it could be damp causing the error.

[Mutti82]

Yes pcm was replaced in August. Checked the replacement and no sign of damp in pcm pins or connector. Also no water has appeared to footwells.  

Would that U0401 mean that possible corrosion in wires or connectors would be somewhere between PCM and ABS modules? And just to be more specific, it's the ABS module which gives that DTC (faulty data from ECM/PCM). Could that faulty data from ecm/pcm be some faulty sensor giving faulty data to ecm/pcm and onward to ABS which launches the limp mode? Starting to get little frustrated because there could be like billion places for this kind of little damp problem. If even those DTCs would give more accurate direction towards the possible place of corrosion. Hell of a job to check every inch of can-bus network, rip off all insulations etc. Would it be easier to just buy brand new wiring loom, about 400€ from Germany + work costs. (don't know how much time that would take to change, needs to pull whole engine up or....??)

There has been no other electrical problems with car, thinking of main fuse box or bcm. But i'll have a look when I get a chance to have warm garage space for few days. And have the location of those modules. ABS seems to be behind battery so requires little work. I'll check ABS sensors and wirings today when changing winter tyres. 

Also I've been starting to think that could this be software issue of one or more control units? I made free "independent garage" account to Ford ETIS pages (quite good thing actually cause can see all installed control unit, tech specs etc) and it tells me that there is updates available for ABS, IPC, TCM, RKE and PAM. Last update check has been made July 2013 and several updates have come after that.

 

Update 30.10.2016 10.00 am: This morning, now continued for third day, again from the first meters limp mode, now also TCM gave U0401 and P1719 (engine torque signal). Also ABS gave U0401, PCM gave P062E. Begins to be no longer intermittent fault.

Update 30.10.2016 6.00 pm: Inspected ABS-sensors/wires, no splices and very flexible rubber insulation. Before began changing tyres, decided to disconnect battery neg.terminal for that time, thinking that maybe "reset" would help get rid of the fault even for a while. And hey, IT DID! No kangaroo-jumping, no DTC or any other symptoms. Drove home and let the car stand still for two hours in quite hard rain and +3 degrees Celsius so that engine cools and all places get damp. Took the car to test drive, still no issues, everything working fine. Next step is test drive tomorrow when going for 75km work trip starting 6.30 am, weather forecast shows still raining and cold. But hmm, if "hard reset" of everything took the issue away (at least for two hours), could this still be just software issue? Cause still, there is god-knows-how-many updated softwares appeared after March 2012 in those 5 control units for which Ford ETIS shows updates is available. If there just would be a chance to see list of updates and what discovered problems those have fixed. Anyway, going to book my car for update to Ford dealer as soon as possible.

[Tdci-Peter]

14 hours ago, Mutti82 said:

But hmm, if "hard reset" of everything took the issue away (at least for two hours), could this still be just software issue?

Maybe, stranger things have happened. And the partial (at least) cure by battery reset is interesting. Please post any results here.

[Mutti82]

11 hours ago, Tdci-Peter said:

Maybe, stranger things have happened. And the partial (at least) cure by battery reset is interesting. Please post any results here.

Well that really was just temporary solution. Drove this morning to work, weather was +2 Celsius and was raining wet snow. 70 out of 75km car worked fine, driving steady, making passings etc. Then 5km before finish, Cruise ON at 85km/h, first ESP light, then all the other symptoms, fault messages and limp mode. So this time no cold motor or accelerations in low gears etc. DTCs again U0401 from TCM and ABS, also that P1719 engine torque signal from TCM. Last one has started to appear every time the symptoms come. I have chance to get my car to workplace oil pit this evening, trying to inspect sensor and fusebox connectors and earth point from engine bay and also from underneath the transmission if I could locate TCM connector. Searching for damp, wet areas or direct corrosion.

[Tdci-Peter]

52 minutes ago, Mutti82 said:

Drove this morning to work, weather was +2 Celsius and was raining wet snow. 70 out of 75km car worked fine, driving steady, making passings etc. Then 5km before finish, Cruise ON at 85km/h, first ESP light, then all the other symptoms

Brrrr, are you in Siberia or somewhere! It is sunny & quite warm & nice here.

All these sort of problems are worse in bad weather. It looks like data corruption is happening on the HS-CAN bus.

The first thing to check is the terminating resistors. And this is dead easy.

Stick a couple of suitable probes (un-bent paper clips can work quite well) in the diagnostic connector pins 6-14, put a DMM across the pair on voltage range, turn ignition on, note reading, turn ignition off, wait till voltage drops to zero (+/- 1 or 2 mV), switch to resistance range to check for 60 ohms.

If you get 60 ohms, try tapping and moving various suspects, eg the fascia around the IC, the connector by the front door sill, the connector in the engine bay fuse box, and maybe the PCM. Look for any deviations. (IC = Instrument Cluster)

If you get about 120 ohms, then there is a disconnection in the bus, or one of the two 120ohm terminating resistors is not connected. I am fairly sure that one of them is in the pcm, and the other is in the IC. And all the other modules in the bus are strung along in between.

It should be stable at close to 60 ohms, any deviations would indicate a problem.

Mutli-drop bus systems like CAN are an absolute nightmare to diagnose wiring problems on, I do not know why automotive manufacturers went down that route. There are cheaper and far superior alternatives, USB is an example. But ranting will not solve this problem! (I have been using mutli-drop bus systems since about 1978, none of this is "new").

Below is a diagram of a Mondeo bus system. I am not sure how accurate it is, it is from fordwiki.co.uk, for models from 2003 on. But it gives some idea, perhaps, of the modules on the bus.

Index to diagram:

1 - Mid-speed CAN bus.    2 - High-speed CAN bus.    3 - Terminating resistors

4 - DLC.    5 - EATC module or ATC module.    6 - PCM.    7 - TCM.    8 - Fuel injection pump

9 - ABS module or ESP module.    10 - Instrument cluster.    11 - Yaw rate sensor.

12 - Steering wheel rotation sensor.   13 - Electrical actuator, turbocharger guide vane adjustment

14 - GEM.    15 - Compact Disc (CD) changer.    16 - Navigation module.    17 - Touchscreen.

18 - Audio unit.    19 - Audio system module.    20 - bluetooth voice control module

[Mutti82]

1 hour ago, Tdci-Peter said:

If you get 60 ohms, try tapping and moving various suspects, eg the fascia around the IC, the connector by the front door sill, the connector in the engine bay fuse box, and maybe the PCM. Look for any deviations. (IC = Instrument Cluster

Which one of DMM wires I should move around the around and in which connector pin (6 or 14) should the other wire stay in? And those connectors in front door sill, engine bay fuse box and PCM... where in those connectors should I stick the DMMs other wire?

UPDATE: Thank you iihs.net for free Ford workshop manual 418-00-1. First pdf is very good picture explaining basics of CAN network and second pdf has 41 pages of direct and accurate diagnostic guides! :)

[Mutti82]

Measured those resistors and all other pin-pin and pin-ground combinations the guide told. All ok. Also opened pcm cover bix once more and contact sprayed connectors and pins, no signs of damp. Didn't get any wiser about the fault. Starting to get really frustrated. Next step getting those updates, they can't do no harm. Called local Ford-dealer, he told that it doesn't sound like software issue and those control units should not usually be updated if they don't directly give fault codes. Oh hell, all units giving connection faults etc have updates available and the car has severe fault... so shouldn't that be enough reason to try updates? Next he said that well yeah they wouldn't do no harm either. Have I gotten wrong but aren't updates usually made for fixing found bugs etc?? :D So at this point I'm open to all chances.

[Tdci-Peter]

5 hours ago, Mutti82 said:

Which one of DMM wires I should move around

The DMM wires stay in the DLC (diagnostic connector) while disconnecting & re-connecting connectors & generally bending wires & tapping or moving various parts. This is to hunt down any bad connections or loose joints. You would be looking for any change in the resistance.

But it sounds like you have done that now, and got a good steady 60 ohms. One problem here is the fault is intermittent, and not very big. Even small disturbances on the HS-CAN bus can have severe consequences. It may be necessary to repeat the 60ohm test quite often, especially just when the car is going wrong.

4 minutes ago, Mutti82 said:

so shouldn't that be enough reason to try updates? Next he said that well yeah they wouldn't do no harm either.

It is worth doing, I would say. Downloading software usually makes heavy use of the CAN bus, and if a module is faulty or has a bad connection, then it might give errors while programming. That would at least help to pin down the fault.

I can understand your frustration. The one time I have had CAN bus problems, it was right at one end, in the IC, and affected the 60 ohm test, so was really easy to pin down. If it is on one of the intermediate modules, it will be much more difficult. TCM is looking favourite at the moment, followed by the ABS module.

The speedometer uses data sent over the can bus from the ABS to the IC. If there are no wobbles or odd readings of speed while the error is happening, then ABS sounds less likely to be the culprit.

 

 

[Mutti82]

I don't know if this is just a waste time, but... started totally new line of inquiry, after googling "engine torque signal" from every make, not just Ford. Several cases where symptoms have been much like mine, also U0401 from PCM and ABS, and P1719 from TCM appeared in many of those cases. Studied this subject last night for 5 hours and came to an idea:

What if that condition I've been thinking as Limp mode (engine malfunction and transmission limited function messages in dash screen, ESP and ABS lights on, Hill launch not available, car bounces like kangaroo if even touching accelator pedal, transmission won't shift up before revving almost max for like 5sec or down before revs are almost at idle) actually ISN'T limp mode? What if those symptoms and warnings are all independent REAL symptoms, caused by something which can affect all of those control modules and engine perfomance? One thing connects those all:

- What is the thing which actually develops (calculated) engine torque signal and delivers it to PCM from where it's distributed to all other control units demanding it?
- What if that torque signal for some reason goes faulty or totally lost, and TCM can't shift gears in optimal torque and revs, up or down depending which way torque and revs are going? Just letting the engine cry many secs before upshifting or letting it almost cough before downshifting, also shifting gear takes like 2secs when normally like 0,2sec.
- What if that torque signal for some reason goes to faulty or totally lost, and PCM just can't command injectors right, making car bounce like hell when trying to accelerate and giving P062E which is in someway affiliated with injector circuits?
- What if that torque signal for some reason goes faulty or totally lost, and ABS and ESP units can't control safety systems when not knowing output compared to wheel speeds, possible skids etc, and can't activate Hill Launch because not knowing when there is enough torque to safely release the brakes?
- What is the thing which actually can be affected by cold and wet air, making it worse especially if has collected loads of crap in time? And is most likely original one in my car, used for 280 thousand km so could be just worn and needs to be replaced?

 

TADAAAAA, answer is: MAF and/or MAP!! 

And now if someone just would pull me down to ground and say "no way, it even can't be possible!" :D But going to buy today MAF cleaner spray and start with that. Genuine Delphi MAF seems to cost only 80€ so won't look to long if cleaning does nothing to issue. Didn't yet find what company manufactures genuine MAP for my car, at least not Delphi cause won't give MAP for cars newer than 2003.

[Mutti82]

Does anyone know what who manufactures Ford OEM MAF-sensor? Or is there any recommendations of other brands? Reminding that my car is remapped to 201PS so going to buy quality MAF, no cheap copies. Is the genuine good enough or should buy some "more accurate" one? Local Ford-dealer wants 258€ for original MAF. :D Looking from internet, Delphi would cost 88€, Magneti Marelli 98€ and Hella (made in Finland) 132€.

[Mutti82]

And just getting more weird! Took off MAF to look for product number for crossrefence for other brands, seems to be 8V21-12B579-AA... and what the heck? For example Delphi catalog offers MAF AF10183-12B1 which is compatible for motorcodes JTBA, JTBB, T1BB, TNBA, TBPA, AZBC, TXBA, TYBA and UKBA (mostly petrol engines and one 2.0 TDCi). My motor is UFBA and when selecting MAF by motor code, it gives AF10255-12B1 which is also meant for FFBA, KHBA, QYBA, AZBA, KLBA, LPBA, QXBA and QXBB. Could that be that already one sensor has broken somewhere in the past and in previous owner had fitted "same looking part from same looking car?? And by knowing that how different is petrol engines air needs versus bigger tdci... could that current maf be just incompatible to handle it's job, especially in cold weather when diesels need more accurate mix ratios to work and emissions to stay within tolerances.

[Tdci-Peter]

5 minutes ago, Mutti82 said:

MAF to look for product number for crossrefence for other brands, seems to be 8V21-12B579-AA

8V21-12B579-AA is a Ford engineering no., and one site said it fits the Mondeo 2011 2.0TDCI. Ford part code is 1516668, and fordpartsuk.com says it is for Mondeo 1.6TDCI, from Feb. 2011. A few sellers list it as valid for your car.

6C11-12B579-AA is listed by other sellers as the correct one for that car. Ford part code is 1376235, and fordpartsuk.com says it is for Mondeo 2.0TDCI, but only until 2010.

So chaos rules, as usual. All the sellers say send your VIN or other code first. The Ford ETIS site may help, if you enter your VIN.

It would be great news if that was the problem. It all seems a bit illogical, but these things are sometimes like that.

[Mutti82]

Finally local Ford-dealer decided to help and sent me message telling (same thing) that from Feb 2011 all Mondeos were started to fit with 1516668. So setback again, no wrong sensor fitted. Of course it's not said that the sensor couldn't be faulty. Much of those have been replaced with same kind of symptoms with much lower mileage. I have original sensor.

Read user experiences from other Ford models and other brands with same kind of symptoms. One known common issue has been ABS-module and/or it's connector. Needs to take out the air filter box and battery to even get close to it. Also software issues with update fixes.

Then there has been issues with IPC corrupting signals even with no resistor problem. Have been fixed with software update.

Have I understood right, that MAP also has it's part of calculating engine torque signal? Had a look on MAP sensor also... should it be usually dry? Cause the part inside manifold was all wet and there was just a little black soot also in that sensor tip (possibly from EGR?). Cleaned it with CRC Air Sensor cleaner. Actual boost pressure loss only in cold AND wet weather doesn't sound too real.

When I have chance, going to have a look to intake, vacuum and boost pipes for cracks. Thinking that maybe small splice will spread more when cold and pipes shrink a bit allowing extra air get in the system after MAF and corrupts MAP readings? Or boost lost and engine not getting enough air? But then again, why not happening in winter when much colder than autumn. Yes, no damp in air. Again, wide shooting, I know. 

Possible damp and/or corrosion in wiring... I don't have a clue anymore where to start searching from, like million places and would it still be possible to see it with bare eyes? 

Also before had driven today, I did as first thing KOEO test with Forscan using laptop. PCM gave P068A. ABS-module gave U0126:00 (Lost communication with SASM) and U0452:68 (Invalid data received from RCM). Any help from those?

Could I get good insurance money if I just leave the car in front of cargo train... saying it just stopped there because of engine fault. :D

[Tdci-Peter]

6 hours ago, Mutti82 said:

Could I get good insurance money if I just leave the car in front of cargo train... saying it just stopped there because of engine fault. :D

Value of dodgy Mondeo: $0.75. Cost of repairs to Track & Train: $1,000,000 or more. Maybe the insurance company might grumble!.

I do not intend to be flippant, I understand just how damm frustrating & annoying this sort of problem is, but you have to have a bit of a laugh sometimes, or it gets too much.

You often mention damp. If the problem does usually go away once dry, either cold dry, or warm dry, then I suspect electronics (pcbs or connectors) rather than wiring. The most likely wiring problem is that water gets inside the cable, and rots the copper. Once this happens, it will always be a bad contact, drying out won't help. Just possibly, there could be partial damage to the insulation, and water or wet dirt can link two wires together, being ok when dry, but I feel this is less likely.

Once a pcb or a connector gets wet, then there will be some corrosion, and this leaves residues on the pcb or connector housing. These residues are often hygroscopic, and become conductive in damp conditions. The problem can go away once dried out. Also circuits on pcbs may be much more sensitive to this sort of conductivity than most circuits in the wiring between pcbs. Generally this will be visible once the pcb is uncovered, unless it is potted & water has penetrated under the potting.

One reason I am uncertain of the MAF / MAP idea, is that in a diesel, engine torque is largely related to fueling, or injector fuel quantity. AIr flow is normally unrestricted, and the mixture varies from very lean, to near stoichiometric. The airflow is important near max power, to prevent over-fuelling, with lots of smoke.

One thing I have just thought of: Have you tested the battery? Low or varying battery voltage has been known to cause a lot of peculiar problems. I can't recall if that was covered in the previous thread.

The "P068A - ECM Power Relay Load Circuit: De-Energized Performance Too Early" code is interesting, but may be just a result of the test. It does not really stack up with anything else.

So I would try to locate the TCM & ABS modules, and see if the connectors & electronics can be inspected.

One thing is a benefit: There is a lot of communication between pcm & IC. And there don't seem to be codes relating to that. So most of the wiring seems ok. The fault is likely to be local to the ABS or TCM region, which is probably in a wet, dirty part of the engine bay. And probably hard to get at, but that is usually the way!

[Mutti82]

About the battery. Factory fitted battery had some deep discharges last winter, 10-15min use of Webasto in those -20-30 celsius weathers and didn't start anymore. Changed it last December to Yuasa YBX5110 Silver High Perfomance (calcium-calcium), so should not be due to change yet. Dealer told that calcium-calcium Yuasa would be good replacement for Ford's original silver-calcium battery. True? At the time couldn't find a single one silver-calcium from stores nearby and had a rush to change that battery because my distance to work is about 100km and car is essential to me. About voltages... is that normal that charging voltage after almost 1 hour of driving at 100 km/h speeds is still 15,1-15,2 with no windshield or rear window heaters, seat heaters etc on? At least live stream for OBDII showed 15,2V last work trip when the fault came up when cruising at steady speed. Came up to thread about intermittent fault where Engine malfunction and connection based DTCs... fault had been in alternator / smart charge system. And when thinking of last winter's problems... somehow a terrible idea of fried / damaged control modules due undervoltage events start to come up in mind. Any sense in these thoughts? Though again, how would damaged control units issues be so accurately weather dependant...

But I'll try to look for TCM and ABS connectors. 

[Tdci-Peter]

16 hours ago, Mutti82 said:

About voltages... is that normal that charging voltage after almost 1 hour of driving at 100 km/h speeds is still 15,1-15,2

Over 15v does sound a bit high. Could there be any bad connections in the battery to alternator or battery to engine & body wires? I usually expect to see about 14.4v, although the recommended charge voltage for silver calcium can be as high as 14.8v. But 15.2 after an hour sounds odd. The in-car measurements can be a bit out, try a dvm on the battery terminals, headlights on & off, idling and at about 2000rpm. It should not vary much (once recovered from starting) in all those four situations.

Automotive components and major electronic modules are specified and designed to stringent requirements for voltage. They are intended to withstand expected abuse, of under-voltage, reverse polarity, and over-voltage due to load dump (sudden battery disconnect while charging). Whether this always works in practice, I do not know. You hear lots of horror stories, but I am sure very few are really true, and a lot are guesses, blame avoidance and suspicion. Module damage from that does not seem to fit your symptoms. But bad connections in the battery wires could fit.

Yuasa are a major, reputable make, and clearly claim that their batteries are good for the Ford basic smart charge system, where silver calcium is specified. I think the battery type should be ok. (I assume you have not got the Econetic or Start/Stop car version that needs EFB or AGM type of battery?)

 

 

[Mutti82]

You assumed right, no Econetic or Start/Stop. And will never be. :D

But if I now take a little break from this subject, because it seems that autumn s**t weathers are over and dry winter came. This morning little under -10 Celsius. And issues have never occured in winter. :) Though going to have a look at the TCM and ABS connectors if I have chance. I'll write here if some major breakthrough occurs. :D

[Mutti82]

In Finland it's so normal that winter almost comes... and one day temperatures raise again, all snow turns to water and... Mondeo symptoms are back. Last thursday morning I was leaving work, car had stayed overnight in rain and as soon as I had driven about 50m bouncing started. Finally not in weekend or mon-fri night so drove it to nearby Ford Dealer without turning engine off even once. Hoping they could now get fresh readings from somewhere. Of course I didn't have reserved time so they only had chance to read DTCs. 8 codes found where 4 was U-beginning ones. They had also called importer if some experiences or knowledge from there. Ford dealer gave me a print of service notice from 2011 where is listed many U-dtcs and some other symptoms, much like my Mondeo has. Notice told that if customer is expresses those symptoms and 1 or more of those U-codes is found, first thing to do is replace BCM to newest version and recode it. If problem does still exist, next thing is to check both wire bunches near both doorstep and under floor console for damp signs.

So decided to continue searching the fault. Today took both front seats and uncovered those wirings. No sign of water in any way, all insulations ok and flexible, floor totally dry. Because my car is former taxi and there had been drilled a hole to roof railing for taxi sign wire, took off driver side front door seal and looked inside A-pillar interiors, no marks of water there either. Took off the driver side end-panel from dash, looked behind steering wheel, no signs of damp. Car is going tomorrow to garage for BCM replacement and getting finally software updates for 5 control units, just in case. Found newer BCM from rear collision car only 75€, needs to be coded to my car of course. If that doesn't cure this issue, it starts to be clear that fault is engine bay or somewhere near tires (abs sensor etc).

If all this continues to summer, I'm starting to be quite good tearing my car apart... ;)

[Mutti82]

And story continues... today I drove to garage for BCM replacement. Left the place, drove steady 80km/h about 30min in quite hard rain and... fault goes on again! This time even worse than ever. Car stalled, I pulled over to safe place.  Reading DTC gave again "Engine torque signal" and two other control units reporting faulty data from PCM. So I first unplugged MAF sensor wire, engine sound or running quality didn't change a bit. And while PCM collects it's values, uses it itself and also sends them to ABS/ESP and TCM modules... still coming back this subject again?

Usually turning off and on gives a chance to drive about max 50m before it goes lunatic again. Now it didn't even give a chance to move 1m. It was enough that I switched transmission to D and raised brake just little bit so car started to move... and at that second ESP lights etc., if even touched throttle car did stall more and rev down to about 600 rpm. Next I decided to check how deep fault is at the moment. No need to even switch to Drive. Just staying in place and raising rev over 2000/min illuminates ESP and Hill launch unavailable. Letting engine idle for 5sec lights go off. VERY weird! And gets even better... tried Reverse and what the hell, car goes backwards like rocket without any symptoms even the ESP light is lit. But not towards, not moving even 1m. 

I had no chance but to call tow truck cause 40km left to home and just highway running. Okay, here we go again. Knew that tow truck would come in about 25min so decided to let engine idle without touching anything so that cabin stays warm. 2min before truck came I decided to make sure that issue still exists so now garage has better chance to diagnose it. And for ***** sake... no, car worked fine again! But too risky to cancel tow truck and try to get home by myself. Of course garage was closing at the moment I got there so decided to drive car to home, 5km which went fine.

So... what the hell I'm going to do with that car? Symptoms get on worse, but just WON'T cut out totally so that could pinpoint fault easier. Towtruck driver has been car mechanic for 30 years and he also said that first thing coming in his mind is faulty MAF or engine bay wiring loom. Wiring loom was load-tested for 4 hours in local Ford Dealer, no issues came. Could it still be that there is tint/corrosion damage inside wires and fault comes only when stayed at least overnight in wet conditions or have been driven in rain for longer distance.... but goes away in like 15-20min idle??? And how would that "revving over 2000/min" count to wiring loom issue?? Faulty MAF though would at least in some way fit to so accurate rpm-value for issue to come. Cause actually, thinking again, those issues have always occured when driving in freeway (steady 80-100km/h and about 2000-2500rpm) or in city (accelerating and when switching from 1 -> 2 or 2 -> 3 and revs at 2000-2500rpm). Or does someone has in mind some other sensor etc which would get damp and kicks in/ affects much in those rpm? 

UPDATE 1: Just found (matter of finding right google words) one post concerning of some Nissan Maxima where ground inside MAF sensor had been corroded badly and it gave exactly same symptoms, first occuring when driving but later getting worse and no matter if he was driving 75mph steady, idling at park or stopping at traffic lights and then accelerating. Corrosion had been enough to affect the sensor data but it didn't create any directly MAF-based DTCs. Other user had commented that he had same symptoms, plus that his car had barely moved after cold start, until he had let it idle for 10min. And another user with same symptoms, had changed several sensors but problem had gone when changed MAF. 

[Mutti82]

Today decided to use some hours for searching those engine bay earth points. First clearly earth cable was found going from power steering pump to chassis. It was badly rusted from pump end so CRC, sandpaper and screwdriver head made it crystal clear steel. Just for exploration I took off air filter housing and hey, underneath it seems to be quite essential earth point. Three wire in an row each with on connector. One bigger like 16mm2 only connected to side of transmission and two smaller about 4mm2 which were coming from inside an intersection engine bay wiring loom (which seemed to distribute wires towards at least ABS, PCM, TCM and engine bay fuse box.

First, all connectors were originally fitted over fat paintlayer, only grounding through bolt threads, not using the whole connector surface. Second, left one of the smaller cables had badly rusted bolt and connector. Third, the bigger cable coming from transmission side was rusted and also conductors badly oxygenated. So screwdriver head, CRC and sandpaper did the job uncovering bright steel from chassis and smaller cables. Bigger looked so bad and beyond sense to even try clear it so bought new, 20mm2 cable from car electrician who manually created right length and sealed visible condutors with waterproof heated rubbertape. Below is attached picture what the earth points looked first. Next to bigger cable there is open hole which goes all the way wheel arch from where water can directly raise to these earths. At the moment of discovery there was still water and sand around them.

As electrician myself (though not specialized in cars but factory automation) I'd say that here could be a potential issue especially when this place was in middle of everything what have given malfunctions and DTCs and wet conditions make conduction ever worse. And because there is so bad oxygenation in big cable, there has been bad or insufficient conduction more than once and cable has heated much. If engine/transmission couldn't ground itself with bigger cable, would next try to use smaller ones which are reserved for control modules and some 4mm2 cable is SO not enough when it's capacity is calculated for engine electronics. We'll see if this finding and fix would even help with issue, maybe cure it.

[Mutti82]

Nope, the problem wasn't in those grounds. Yesterday fault came again when temperature had been just above 0 Celsius and snows turned to water. Once again ESP light, hill launch off and then car drove bouncing like hell. Only clear thing at the moment is that the fault is in system which only affects engine, transmission or brake system when driving forward. Cause again when fault was still on and ESP light, I switched to reverse and press pedal to floor car just launched like rocket with no issues.

Friend suggested fault could be in ABS/ESP/TCS module or it's connector (or one of the wheel speed sensors or it's connector though I roughly inspected them already) got damp/corroded inside, because according to ESP/TCS affects from 0 km/h when forwarding but not before 25-30km/h when reversing (if at all cause might not even understand speed signal from wheel spinning backwards). Any sense? 

Later evening yesterday car ran fine again, so now waiting for it to fault again... going to switch ESP system off from dash computer, see if that does anything... if runs fine after that, at least better pinpoint towards cause of issue... 

[Mutti82]

I read some more about ESP/ABS system. Those ABS sensor seem to provide faulty signals intermittently for a long time, not leaving any DTCs pointing towards them. Magnets from sensor could be worn, wire or connectors rusted or Also gave some thought about symptoms when they occure. Every time car "bounces" the ESP light flashes and/or is lit permanently. 

Usually when fault starts in highway speeds, "bouncing" feels very much faster and lighter. If I ease off gas pedal to almost zero, car holds it's speed. If I try to press gas pedal even a bit, bouncing starts immediately and speed slows down. The slower the speed, bouncing effect becomes more powerful but it's pace is slower. 

Usually when fault start in city speeds, it is slow paced but powerful. From full stop, if I press the gas pedal to floor, car manages to pick up some speed, VERY slowly though and bouncing like hell. As soon as speed rises, bouncing becomes faster paced but lighter, not trying to hold car so much. And when getting to target speed and bringing gas pedal to as high as possible just to maintain steady speed, bouncing eases off.

Worst scenario was when I had to call tow truck: when tried to drive forward, as soon as switched to D and released brake pedal, revs dropped to about 400-500/min and just couldn't move 1m, felt like I was holding acceleration and brake at the same time. But I had driven almost 10km with fault on before had chance to pull over. Brakes were probably quite hot at that time already and had maximum effect to keep car still and fighting against engine trying to move it.

Thinking of all this, what if it isn't actually the engine fault what is making that bouncing... but esp system throwing false cycles like anti-skid braking when gas pedal is pressed to levels where it should accelerate the car, not when at maintain level??? Any sense??? So would be pointing towards wheel speed sensor, connectors, wirings inside wheel arch and ABS/ESP module.

[Mutti82]

Just made On Demand Self-Test (Keys On Engine Off) to all control modules individually with Forscan PC-version and checked DTCs after that. Below a screenshot of fault codes found. Those U-codes what ABS-module reported are "lost comms" to BCM, SASM and TCM, last one is invalid data from RCM. Should I still concentrate my search to somewhere else but ABS module or it's sensors?

[Tdci-Peter]

19 minutes ago, Mutti82 said:

Those U-codes what ABS-module reported are "lost comms" to BCM, SASM and TCM, last one is invalid data from RCM. Should I still concentrate my search to somewhere else but ABS module or it's sensors?

That test run is quite specific in putting all suspicion on the ABS, or its connections. The other previous likely suspect was the TCM, but this test shows that unit to be ok.

The PCM error you have had before, it may be a side effect of the test. The BCM error (rear climate control or sunroof switch) seems unconnected.

As you have said, all the symptoms could be down to an ABS fault, applying the brakes and cutting power when not wanted. If it was the wheel sensors, these would normally raise specific codes, these U faults are more likely to be an internal error in the module itself.

I would repeat the 60 ohm resistance test I outlined on 31 Oct, as it is easy to do. It tests the integrity of the HS CAN bus from end to end, and into the PCM & IC modules. It does not test the spur leading to the ABS. I would re-run the self tests the next time it misbehaves. But then I think it may be time to replace the ABS module, or more likely, the entire ABS unit, as it may have to be removed anyway to get the module out, and the electronics may not be available separately.

It may be possible to have the unit tested & repaired, but I have not heard of this being done.