Faulty ECU / Faulty ABS Control Unit

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chris_smith
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Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

Hello :hi:

I am having endless problems with my 2008 Cross Polo's electrics and turbo :(

The lastest my mechanic says is that my ECU is gone and needs to be remapped, but upon further research, it seems a lot of people online say it might just be the wiring and earthing of the ECU.

These are the problems I'm facing
  • The engine loses power and judders when accelerating. The fault normally goes away if the ignition is turned off and the engine is cooled down before restarting. The diagnostic says there is a communication error between the ECU and turbo. The wastegate has been adjusted.
  • The ABS light is on, the diagnostic says it is not getting power from both wheels sensors (l/r) but a few different mechanics say there's nothing wrong with both sensors or their wiring and could be an issue with the ABS pump or control unit.
  • The speedometer isn't working
My worry is that if the ECU were bombed, the car wouldn't start. Which to me makes sense that there could be a wiring issue, however, I had a brief look through the wires connecting to the ECU and they look clean.

I haven't had my battery tested, but it wasn't replaced too long ago.

Would appreciate anyone's help here. This has a few auto electricians and mechanics stumped.
smoke.machine
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Re: Faulty ECU / Faulty ABS Control Unit

Post by smoke.machine »

Start by inspecting the fuses on the battery and the earth cables
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Ashveer03
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Re: Faulty ECU / Faulty ABS Control Unit

Post by Ashveer03 »

Was the any work done to the car before all these issues?

The wheel speed sensors and speedometer is probably linked somewhere..

Regarding the shudder and low power - u could have a problem with the Vanes on the turbo getting jammed or the actuator not moving enough, could also be a faulty vacuum solenoid box.
Was the turbo "adjusted" before or after the problem?

Post the dtcs that u retrieved.

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chris_smith
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

I checked all the fuses and they look good.

The turbo was recently reconditioned and no work was done prior to the problems.

I took the ECU out and tested the socket pins with a multimeter and only the one socket works. The other socket plug doesn’t show any readings.

Has anyone tested an ECU like this before?
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Re: Faulty ECU / Faulty ABS Control Unit

Post by Ashveer03 »

Do u have any references that u could use to compare the results of ur "tests" to?

The first thing to check in wiring problems on a 9n polo is the main earth cable from the battery to the strut tower. It causes most of the electrical issues.

As I said, post the codes and maybe people would have more info to help u.

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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

I've been able to get an OBDii tool and check the codes myself.

I made a brief list of things to check and look through.

See the link below, I listed the error codes at the top of the doc:

https://docs.google.com/document/d/1QVK ... sp=sharing
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

Error codes are: P0600 & P0234
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Re: Faulty ECU / Faulty ABS Control Unit

Post by panic-mechanic »

Error codes are:
P0600 - yup lost the link to the engine control modue. So low voltage , harness fault or dying ecu
P0234 - overboost condition.
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

Thanks guys, when I get this fixed I’ll let you know what the fix was
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Re: Faulty ECU / Faulty ABS Control Unit

Post by BatteryWorldPtaEast »

Hi , I had the same issue with my POLO after work done and ended up removing all the fuses on the battery and cleaning them including where it gets contact at the bolt that holds them down . Fine sand paper works and I cleaned the battery terminals . Also check all the small fuses next to those on the battery in the small square cover as there is also a fuse for the ABS.

Hope it helps.
Daily drive : Polo TDI Sportline 180 Hp 349 Nm ATW (Trevor's Custom Map) At Night Dyno
Wife's : 1.9 Tdi Touran
Son's : Cross Polo 1.6 Tdi
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chris_smith
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

BatteryWorldPtaEast wrote: Tue Jan 08, 2019 8:18 am Hi , I had the same issue with my POLO after work done and ended up removing all the fuses on the battery and cleaning them including where it gets contact at the bolt that holds them down . Fine sand paper works and I cleaned the battery terminals . Also check all the small fuses next to those on the battery in the small square cover as there is also a fuse for the ABS.

Hope it helps.
Thanks, what did you use to clean them?
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Re: Faulty ECU / Faulty ABS Control Unit

Post by BatteryWorldPtaEast »

Hi , it is in the post :
Fine sand paper works and I cleaned the battery terminals .

Have you removed the fuses on the battery ? They crack and you will not see it.
Daily drive : Polo TDI Sportline 180 Hp 349 Nm ATW (Trevor's Custom Map) At Night Dyno
Wife's : 1.9 Tdi Touran
Son's : Cross Polo 1.6 Tdi
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Re: Faulty ECU / Faulty ABS Control Unit

Post by BatteryWorldPtaEast »

Hi , The ABS error will not clear if the fuses are fixed . You need VCDS to clear it .
Daily drive : Polo TDI Sportline 180 Hp 349 Nm ATW (Trevor's Custom Map) At Night Dyno
Wife's : 1.9 Tdi Touran
Son's : Cross Polo 1.6 Tdi
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chris_smith
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

Yes I know - the car is with the auto electrician at the moment. So we'll see
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Re: Faulty ECU / Faulty ABS Control Unit

Post by chris_smith »

My car is fixed. Thought I would provide the solution to help anyone else with a similar issue,

The ECU was fine, despite evidence that it could be failing.

Regarding the turbo going into limp mode, this was an issue with a power cable going directly to the turbo that wasn't connecting properly.

Then regarding the ABS Module. I sourced a module from a guy with the same Polo and this turned off the ABS and Power Steering Lights but the speedometer still was not working.

Apparently, the bearing housing was loose and broken. The play between the wheel sensor and the broken bearing meant that both sensors weren't giving a signal.

So if you have problems with the speedometer, also check the bearings!

Thanks for all the help.
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Re: Faulty ECU / Faulty ABS Control Unit

Post by panic-mechanic »

So how was the ecu not communicating fixed?. broken canbus cable or what was the issue?.
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'05 Audi A6 3.0L TDI Avant
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