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Ford Cmax ECU fault


Trigger67
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Got a 2007 petrol Cmax. Cut a long story short, after breaking down and going into limp mode, the codes were read by RAC which said throttle body or coil pack fault. Took to local garage as the fault was hard on, found not firing on two cylinders. Swapped coil packs and same two not firing. ECU wiring loom was tested by the garage who say its ok. Was advised the fault probably was the ECU. ECU removed and sent for testing. They say it's burnt out and unrepairable. I have no problem in having to buy a replacement as the old one is clearly knackered but I am worried that if I do and the cause of the burn was not internal to the ecu, i will burn another and waste a lorry full of cash. Would anyone have experience of this and have any advice? Do these burn out or does something external cause it to happen. Is there any tests people could recommend before I fit a new ecu? Any advice on the best place to get a replacement ecu also appreciated.

Steve

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6 hours ago, Trigger67 said:

Was advised the fault probably was the ECU. ECU removed and sent for testing. They say it's burnt out

There was one case I have seen where it was claimed that a faulty throttle valve damaged the ECU. See:

It is not impossible that a faulty coil pack can do the same. As you have had the coil pack changed, that should not be a problem. Might be worth having the throttle valve properly tested though, Especially as it was a suspect.

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Thanks for the reply Peter

Very interesting thread. I suppose that was my worry in that was there something that caused the ecu to fail. When the code reader was used, two codes came up -

P2110 throttle actuator fault

Engine systems failure with a misfire on no1and 4 cylinder

when the coil packs for 1 and 4 were swapped with 2 and 3, the fault stayed with 1 and 4. Gonna get the ecu back and talk to the tester (ecu tester.com) to understand how bad the ecu burn up was. Is there anyway of testing the throttle actuator to see if it is defective? 

Thanks

Steve

 

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Thanks for the reply Peter

Very interesting thread. I suppose that was my worry in that was there something that caused the ecu to fail. When the code reader was used, two codes came up -

P2110 throttle actuator fault

Engine systems failure with a misfire on no1and 4 cylinder

when the coil packs for 1 and 4 were swapped with 2 and 3, the fault stayed with 1 and 4. Gonna get the ecu back and talk to the tester (ecu tester.com) to understand how bad the ecu burn up was. Is there anyway of testing the throttle actuator to see if it is defective? 

Thanks

Steve

 

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Just rang them. They said the ecu has a dead short but can't find where! Would you think that this has been caused internally only. Bit difficult to say I know without seeing it or having all the info.

 

I can get refurb one but need to send it with the old one away to reprogramme it. Will this mean it will be ok with original keys and the immobiliser will work?

Steve

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13 minutes ago, Trigger67 said:

They said the ecu has a dead short but can't find where! Would you think that this has been caused internally only.

In my experience of general electronics, "dead shorts" are usually caused by external factors, such as driving into an external short circuit that overloads an output, or a high voltage, high energy surge coming in from somewhere. But without the location of the fault, it is unclear. I would have thought if the fault was the output driver on one pin, eg the throttle, then it should be locatable, and likely to be curable. But sometimes the fault propagates internally, and can damage one of the pins of the main processor chip, which would not be easy to fix.

All the throttle valves I have seen schematics for (on the Focus mostly), are the same type. 2 wires driving an electric motor, and 4 wires from & to the valve position sensor. The position sensor has a Vref pin (probably 5v), a ground (0v) pin, and two signal pins. It may be just a pair of pots, or it may be something a bit more electronic, possibly with a pwm output. Some quick testing with a multmeter on ohms / continuity / diode ranges should establish where the motor connections are by the low resistance, and whether the sensor is pots or electronic. The motor can be powered to move the valve without needing to connect the sensor. Any experienced electrical / electronics person should be able to test one of these.

In view of the P2110 DTC, we must assume there is a fault in the throttle circuit. If nothing shows up in the throttle itself, a thorough examination and continuity test of the wiring from pcm to valve would be wise. Damage in the loom, causing wire to wire shorts could easily damage the pcm.

More information on the error location would be helpful, is it related to the throttle motor driver, to the sensor, or something else. "A dead short somewhere" is not very helpful!.

It should be extremely difficult to read the PATS (key) data out of the existing pcm, not much point in it if it was easy!. It may be that the PATS system has to be re-programmed once fitted to the car. This can be done by Ford IDS (any ford specialist garage should have it), or by Forscan, more accessible to DIY & individuals.

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Thanks for taking the time to reply so in depth.

I am getting the ecu back and will do some do testing as you suggest. I have also downloaded forscan and await an OBD2 USB adaptor.

Will let you know how I get on.

Steve

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Peter

Pretty sure it's just the ecu now. I am going to get one but would welcome some advice. I am sure I read that it can't just be plugged in and it wil work. Do I need to buy the instrument Parnell and keys as well.  Does it need programming to the car or the car to it? Is there a way of doing it with for example forscan.

Thanks

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10 hours ago, Trigger67 said:

 Does it need programming to the car or the car to it? Is there a way of doing it with for example forscan.

There is information on the Forscan site which says it can initialise a new pcm. But it is not very easy. There is an initialise module procedure.

From the Forscan site:

" 2. Focus Mk2/CMax

Module initalization function is used here when instrument cluster (HEC or IC) and/or PCM module is replaced.

If HEC/IC or both HEC/IC + PCM are replaced, the following sequence of actions should be performed:

i. Erase all keys (Single coded or timed access have to be obtained)
ii. Program at least 2 new keys
iii. Do module initalization (Dual coded access may be required)

If only PCM is replaced, the steps (i) and (ii) are not necessary, and only step (iii) have to be executed. "

This was in: http://forscan.org/forum/viewtopic.php?f=6&t=1500

For more on PATS & Forscan: http://forscan.org/forum/viewtopic.php?f=6&t=839

If you have a new (non-working) pcm, you do not have much to lose. It is not something I would play around with on a working car, though!

--

Yes I have seen those pcm / IC / lock barrels / keys kits salvaged from other cars.

No real guarantee it will all work, and quite a lot of work changing the lock barrels. I think I would try the Forscan route first.

If your existing pcm is useless anyway, you could experiment on that.

Both the IC & pcm are involved in PATS in the mk2 Focus.

There is other info in the pcm: VIN, a copy of the oddometer reading, possibly some part specific calibration data. (On some diesels (for example), injector calibrations are kept in the pcm, & Forscan has a procedure for this. I am not sure if this applies to petrol cars.)

 

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Thanks Peter,Been looking on eBay. Lots on there. One question I have seen one that is identical but I have 7m51 12a650 VC and the one I have seen is 7m51 12a650 VE. Do you know the significance of the last two letters and whether a different serial number one can be fitted?

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6 hours ago, Trigger67 said:

7m51 12a650 VC and the one I have seen is 7m51 12a650 VE. Do you know the significance of the last two letters and whether a different serial number one can be fitted?

No, is the simple answer, I do not know!

I do know that in some cases those last two letters are significant, and may be for different variants. Safest to stick with the full code.

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