ECU Problem maybe

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Keir
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ECU Problem maybe

Post by Keir »

good evening all,

I had my c4 with the garage today, for that abs rubbish that is still haunting me
the guy said there was a ton of fault codes up,
i didnt even bother to ask him what they were,
however he did tell me that my ECU has a problem
can anyone shed any light on this , do ECU's give trouble ?

anyway any help or suggestions would be greatly welcomed

regards Keir
Hell Razor5543
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Re: ECU Problem maybe

Post by Hell Razor5543 »

I would take it to a different garage, for a start. There are numerous ECUs in a car, and without knowing which one has the problem it would be impossible to say what the problem is.
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GiveMeABreak
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Re: ECU Problem maybe

Post by GiveMeABreak »

Keir wrote:
28 May 2019, 20:58
good evening all,

I had my c4 with the garage today, for that abs rubbish that is still haunting me
the guy said there was a ton of fault codes up,
i didnt even bother to ask him what they were,
however he did tell me that my ECU has a problem
can anyone shed any light on this , do ECU's give trouble ?

anyway any help or suggestions would be greatly welcomed

regards Keir

Keir - The idea is that there are lots of individual ECUs over several data networks on the vehicle. They are controlled by a master computer if you like called a BSI. When something goes wrong the ECU can inform the BSI and if appropriate, it will store a fault code, that can later be retrieved with a diagnostic tool, to help troubleshooting.

The ECUs are rarely at fault - but the components they control can fail like anything else. It would of been helpful to have a list of the fault codes, as we could of helped with troubleshooting. What is important is that you have a competent mechanic or garage that understands that fault codes can be symptomatic of another component further up or down the line. So if one component is failing, it can pass on incorrect data or no data at all to another ECU that relies on it to do its particular job. If the second ECU gets faulty or no data, then that ECU can flag up a fault.

So it's important to understand all the related faults and use these as a guide to try and get back to the main culprit. So don't immediately think that there are lots of issues - it may simply be one component.
Keir
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Joined: 24 Apr 2019, 12:54
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Re: ECU Problem maybe

Post by Keir »

yes agree with you GiveMeABreak

im not well up on car eletrics as it were, at all,
however I usually start with sensors when stuff goes worng.
I didnt get the chance to see the fault codes as i wasnt there,

so where to go from here ive no idea
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GiveMeABreak
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Re: ECU Problem maybe

Post by GiveMeABreak »

So the first step is to get it diagnosed (preferably by somebody with a Lexia diagnostic tool). Run a global test and record all the fault codes. Post them up here and we can start to see what each says which will give you a clue to troubleshooting. This is what a garage would normally do. There's not much we can do here without them to be honest. :wink:
Keir
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Re: ECU Problem maybe

Post by Keir »

Good morning all

Marc can you tell me how to upload an image please?
Keir
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Re: ECU Problem maybe

Post by Keir »

Front right speed sensor
Deviant
Permanent

Engine control unit, absence of clearing of the ASR/MSR
reference value

Permanent
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Paul-R
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Re: ECU Problem maybe

Post by Paul-R »

Keir wrote:
29 May 2019, 11:12
...how to upload an image please?

viewtopic.php?f=9&p=516529#p516529
Keir
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Re: ECU Problem maybe

Post by Keir »

Cheers Paul. I posted the faults manually 😂😂
RichardW
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Re: ECU Problem maybe

Post by RichardW »

Ah, a deviant ABS sensor :lol:

You really need to see the live data to see what the ECU is (or isn't seeing). The fact that the light goes out suggest that the sensor passes its initial resistance check, but then the signal is not coherent somehow. Has it had a new wheel bearing? I'd have a very good look at the back of the bearing to see if there any signs of distress on the mag track, they can be easily damaged.
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GiveMeABreak
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Re: ECU Problem maybe

Post by GiveMeABreak »

Keir - I really need the fault codes to be able to help
Keir
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Re: ECU Problem maybe

Post by Keir »

Thank Richard and Marc.
I don’t have access to the actual codes
I’ll see what I can get dug up