"A cheap source of twisted-pair wiring would be a long ethernet cable (round style for ease of disassembly). Believe Cat-5e is 0.5mm2

Best of luck to you!"

Actually I didn't think of that. I do have loads of old ethernet cables in my garage (years ago I dabled in IT stuff). I did the cabling yesterday evening using some thin mains cable, stripped the outer off and then twisted the blue and brown wires. The car does start fine after doing this, so that is good, ESP light seems to be on all the time now. The car has had previous problems with ESP but the light had been off for a while on the lead up to the recent problems. Not yet actually road tested it, still need to do some minor reassembly, taping up cables, reinstalling battery box. It got too dark to finish it.

for the benefit of anyone reading this thread at a later date if they are trying to solve a problem. 

The ESP light is on all of the time now. Having investigated this further, I think the car has a yaw rate sensor under one of the front seats (driver's seat I think but not sure). I think this should be connected to the HS canbus ( found a pic of one on ebay that had the wires conncected and it seems to show the colours for the HScanbus) but I do not have it connected to the HS canbus on my rewiring of the HScanbus. I do not now have any HScanbus wires any further back from the dashboard. 

This might actually be a benefit on this car I was working on as it had a previous intermittent problem whereby the ESP light would come on now and then (in normal slow driving), and when it came on it would make the car drive in a jerky manner. Now the ESP light is on all of the time and it does not adversely affect the power. So by a fluke that seems to be a benefit on this car now.

Just mentioning it in case some mad person copies what I have done and then is not happy if their ESP is no longer working.

In the wiring diagrams on this forum for the focus mk2.5 there is a diagram for the HScanbus and it does not mention the Yaw rate sensor.

1 hour ago, isetta said:

I think the car has a yaw rate sensor under one of the front seats (driver's seat I think but not sure). I think this should be connected to the HS canbus ( found a pic of one on ebay that had the wires conncected and it seems to show the colours for the HScanbus) but I do not have it connected to the HS canbus on my rewiring of the HScanbus.

Yes, it will have the yaw rate sensor on the floor, but it is connected to the ABS (called the ESP module on the pic below), and its CAN bus line comes via the ABS module, but passes through the dreaded C113 connector back into the cabin.

If you need or want to try to cure this, then some info is below, and is from the same schematic.

As this CAN connection comes from the ABS, and is marked as CAN2 on the drawing, I rather suspect it is electrically re-transmitted, so is electrically independent of the main HS-CAN bus. So breaks in it will not affect the main bus. But quite possibly it is logically part of the same bus, and appears as a node on the bus. USB, for instance, works like this for all nodes, they are all electrically separate links from one transceiver to just one other transceiver, but logically all the transceivers seem to be on one bus. That is why USB is so much faster (in bit rate) than CAN. Simple 1 to 1 links are vastly superior, electromagnetically, than complex multidrop buses with lots of spurs. (I think CAN should really be called CAN'T, but that is just a maverick personal opinion!).

they don't make it easy do they. So the yaw sensor is linked to the ABS/ESP unit by  it's own separate canbus wires, but the wires are the same colour as the main HScanbus wires and are bundled in the wiring loom with them.

I do have pins 25 & 29 on the ESP unit connected (I think) , but I have them connected to a short spur on my new main HScanbus wires. Obviously not as per the above diagram. Perhaps I am lucky I have not created more problems.

We can live with the ESP light staying on all of time (at least I think we can, as far as I can recall, the ESP light being on does not affect the MOT test - can any MOT testers please comfrim?)

 

An update. Since my last posting the car has been used many times, some short journeys, some longer journeys (about 250 miles in total)and had driven / started totally fine , until Monday this week when it had the same fault, driving up hill, ping ping ping- engine malfunction, throttle not doing anything. Oddly it was in the same place that it happened the first time this problem happened. Turned off engine, restarted, seemed to be in limp mode, drove another mile, turned off, restarted and it was fine and has been since then.  

The car is clearly better then it was before I started working on it, but we can't rely on it. 

I have written so much in this thread that I can't remember everything I have said. I don't think I mentioned earth wires. I have cleaned up earth wire points under the battery box and on the passenger and drivers side inner sills/doorsteps (under the plastic doorstep trims on top of sill box section and close to these on the innersill under edge of carpets.

I thought I would add this message in case anyone wondered if it was fixed when they have a similar problem and are reading it in the future

update- car still going - My brother even drove it from Sussex to Luxembourg and back a couple of weeks ago. It only went into limp mode about 8 times he says. turn off and engine restart sorted it each time. he says he is now an expert in doing this quickly as the car is rolling.  I couldn't put up with it if it was mine. That's easy for me to say as I would have the money to replace the car but he hasn't.

I bought him a tunnelrat wifi obd code reader as a present. I told him to put forscan on his phone and check fault codes frequently. But he always says he hasn't got round to putting the app on his phone. I know you have to pay for forscan for a phone (about 6 quid I think).

I try to help him but there's only so much I can do.  It will fail the MOT in December due to ESP light being on (I have checked MOT manual and it is in there, ESP causes fail whatever age the car is). I know the ESP light is my fault due to not wiring up the yaw sensor to the canbus.  Best solution there might be to dismantle instrument cluster and destroy the ESP LED light. Who needs ESP anyway - yes I know it's compulsory on all new cars these days. 

not updated for a while as didn't want to jinx it. Since the last post I have not done anything further to fix the issue but it has been fine since then. car used regularly and sometimes does journeys of 150 miles and no issues relating to all the above stuff. Other stuff has gone wrong but the canbus / limp mode issues have been fine. (I had to sort out ESP light for MOT).

Thought I should update this in case anyone stumbled accross this when trying to fix similar issues 

Got a similar problem. 09 1.6 TDCi.

Engine malfunction. Can't scan the car. Dash shows U2510 and U1900.

Re soldered Dash connector.

60 ohms at OBD connector.

Fuses all good.

PATS led is saying 1:6

Checked power and grounds at PCM connector. All good. Canbus signals good at PCM.

Car behaves same even when PCM is unplugged.

I have now taken PCM off and powered it up on the bench. It draws about 200-300mA. Tried to connect ForScan to it directly on pins A3,A4. Won't connect.

So I have to assume the PCM has had it. Not sure if there is any other diagnostic software I can try, direct to the PCM, or a "Are you there?" Canbus message I could send it with CanHacker?

On 6/30/2019 at 8:35 AM, isetta said:

Dave Sport TDCI: I have not ignored your posts . I have considered if the cluster is at fault and have raised a query on if this can be ruled out by my findings as per my post yesterday. 

"based on the info above the ohms on pins 6 and 14 of OBD socket should be 60 but will show 120 if a break. If I take a reading with the plug/socket disconnected in the engine fuse box &/or the plug/socket disconnected in front of the front passenger door and it shows 120 then does anyone reading this agree that it seems that the instrument cluster canbus connection seems OK, as if there was a break there then the ohms would now read infinity wouldn't they?  as if cluster fault it is not connected to the ECU end of the canbus or the instrument cluster end of the canbus."

I don't want to take the cluster if my findings do indeed rule it out. 

TDCI-Peter - thanks - it seems there are more connections to the canbus wire than i thought.  On an old Cortina it was easy to visually look at where wires went. On the more modern cars the number of wires has increased exponentially and everything seems hidden. You can't just open the bonnet and see everything clearly.  I suppose the upside is we do now have cars that do almost double the mpg of Cortinas.

 

Thought I should reply as it saved a mechanically sound Focus Titanium from the scrap yard.

Was getting intermittent communication faults, then all modules  failure. This went away when I soldered the cluster.

Few months back replaced failed LCD on the cluster and checked the solder joints. Had seen talk of failed joint on various forums so was curious to check mine out. Could not see any obvious dry joints. And now jerking the wire at the back did not cause faults to pop up. This falsely made me think cluster is fine.

Cleaned c90, all fuses and relays but it still came back.

Issue only popped up mid journey with the engine hot and would go away when the engine was left alone for a few hours.

To me this seemed like a joint somewhere disconnects when heated.

Resistance was 120 with just c90 removed and 60 with everything connected. I never managed to measure resistance when communications failed. This was partly because it always failed at really inconvenient times.

Decided to resolder the cluster, but I was skeptical as visually the joints looked fine. Held the iron for atleast 5 seconds and physically vibrated the pin with molten solder.

Now this maked sense as the PCB is multilayered and a good looking top joint doesn't mean the bottom layers are fine.

Have driven for over 200 miles since and have not seen the coms issue!

Hey guys new to this site and have the same problem with my 1.8tdci. I'm no good with all the electrical talk. Could somone put into simple people terms where to start with this. Would be much appreciated 

25 minutes ago, Robert1983 said:

Hey guys new to this site and have the same problem with my 1.8tdci. I'm no good with all the electrical talk. Could somone put into simple people terms where to start with this. Would be much appreciated 

This is a really old post. Start a new one and explain what issues you are having please

Just to update the life of my brother’s focus mentioned by me above.  Car was fine after September 2019 with regard to canbus problems. Car was scrapped dec 2020.  Loads of other things went wrong and in dec 2020 the mot and tax ran out. He had nowhere to park off road.  He drove it to the scrap metal yard where is was destroyed. He removed the battery and headlamps, nothing else. Sad end to what I thought was a very nice car (when running correctly ).   1.8tdci mk2.5 estate.  Made 2008. First reg near end of 2009.  Police car for first three years.  About 150k miles at the end.

On 4/2/2022 at 8:49 AM, Robert1983 said:

have the same problem with my 1.8tdci. I'm no good with all the electrical talk.

With a 2006 car, i suggest looking at my pdf: https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=40491

It tries to explain the most common problem in fairly simple terms.

For a basic understanding of electrical stuff, get a multimeter, browse the internet, there is lots of good stuff (and even more rubbish, but filter that out!), about amps and volts and ohms, and resistors in parallel and series and other basic ideas. I learnt the basics by playing about with things, like trying to get 3 motors in 3 Airfix models to run at sensible speeds from one power supply. I was about 13 at the time!

While I could explain from the real basics, it would take a very long time, and there is no substitute for practical experience. When working on a car, practical aspects like how the hell you make reliable contact with a connector socket you can barely see, and only feel with one hand while lying upside down between the seats, can be far more crucial than 3 years at university learning a load of theoretical nonsense!

(In defence of the University system, some of the things I learnt in my 3 years there have proved very useful, They range from how to drink 6 pints of strong ale and still stand up, to an understanding of the laws of Thermodynamics, which explain why batteries, especially Lithium, are ultimately a dead loss. Though trying to do both of those at the same time could lead to interesting but confusing results!)

 

 

Just to say a big thanks to this thread. It helped me to fix my 2008 Ford Focus Mk2.5 1.8 diesel. Engine wasn't starting, throwing P1622 immobiliser ID does not match. Reflowed the instructment cluster a few times and replaced main earth cable. But didn't know there was 3 more earth connections under the air intake box. Connections weren't broken but in very bad need of a clean. Once cleaned the engine started. Cleared the codes and they haven't came back yet so fingers crossed. I found this video very helpful too https://youtu.be/BeMoIvHNmiE.

Posting just in case it helps someone else 👍

I realise that this is an old topic but wanted to ask you where did you find the wiring diagrams. I could do with them I have a 2009 1.8 Tdci C-Max here that came to me with a burnt out power wire to the main fuse box in engine. Some has bodged a wire onto the positive so that it made a connection. But I am not happy with it and would like to rewire it. The Car's has the same problem as your brother's one I believe. I have had the ic repaired and can rule it out. I had no coms to Pcm but after playing around with the wiring in the engine fuse box I have power now to Pcm I believe that the broken power wire to fuse box maybe causing the issue but need to see where it goes to see if I can replace it. Thanks for any help given. 

20 hours ago, alicavi said:

where did you find the wiring diagrams.

Focus Mk2/2a (C-Max almost the same) Wiring Diagrams are here:

https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42087

And for Mk3 Focus:

https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42086

 

3 hours ago, Tdci-Peter said:

Focus Mk2/2a (C-Max almost the same) Wiring Diagrams are here:

https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42087 6.49 MB · 3,381 downloads

And for Mk3 Focus:

https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42086 5.56 MB · 2,846 downloads

Thanks Peter 

 

On 7/8/2024 at 2:58 PM, alicavi said:

Thanks Peter

The diagrams are large & complex, and can be hard to follow to start with, if you want help just post here. There is info about wire colours and connector pin-outs etc, but not always easy to find.

I am having identical problems with my 09 Titanium Focus. Not much help to you I know.

On 7/23/2024 at 8:08 PM, outrider said:

I am having identical problems with my 09 Titanium Focus.

I assume you are referring to Isetta's description back on the 1st page, of lack of throttle response, Immobiliser locked on, and failure of diagnostics.

These 3 together point to a CAN bus fault, but not to the simple Cluster connector - a fault there leaves the CAN bus intact from DLC (Diagnostic socket) to the ECU, which is enough for Forscan to at least make connection and get some info.

With the Focus schematics and all the info on connector locations in this thread, there is plenty to go on. But tracking down intermittent electrical faults is a nightmare - Test everything at least twice, and be prepared to back track and start again. If the fault is in one section of the harness, but can not be fully located or cured, bridging a whole section of the bus is possible, as Isetta did. But try to keep to roughly the same cable run and length.

On 7/27/2024 at 11:39 PM, Tdci-Peter said:

I assume you are referring to Isetta's description back on the 1st page, of lack of throttle response, Immobiliser locked on, and failure of diagnostics.

These 3 together point to a CAN bus fault, but not to the simple Cluster connector - a fault there leaves the CAN bus intact from DLC (Diagnostic socket) to the ECU, which is enough for Forscan to at least make connection and get some info.

With the Focus schematics and all the info on connector locations in this thread, there is plenty to go on. But tracking down intermittent electrical faults is a nightmare - Test everything at least twice, and be prepared to back track and start again. If the fault is in one section of the harness, but can not be fully located or cured, bridging a whole section of the bus is possible, as Isetta did. But try to keep to roughly the same cable run and length.

Hey thanks for the advice. Thankfully it seems my problem was the cluster connector. After strugling through with the car going beep beep beep '' ENGIN FAULT'' when going over a bump in just the right way, then a christmas tree of lights and '' ACELERARIN REDUCED''. Then refusing to restart unless I punched the dashboard as I turned the key.  Using  cheep diagnostic reader showed a CANbus Failure and No Connection when the car waas refusing to start. Resoldered the cluster connector on the circuit board which was very fidderly but doable with aa good pointy soldering iron and car resetting the needles. I notice my fuel guage is running a little higher than it should. But that keeps me out of the empty. So far So good. Only thing I know is not working though is the seatbelt warning light. I know its fitted cos it lit up one time when playing up. So the next big headache is getting it through the MOT in a months time. I know aa lot will need doing but I love the car and want to keep it going for as long as possible.