TD5 Driver Demand Faults

OK I think my problem is somehow related, I have just shaken all of the wiring behind the dash & above the fuse box, cleared the faults & it started OK I can now rev the engine & with the engine off idle it is fine but if you leave it at idle for a few seconds the management light comes on again & it will not rev.

The voltage via HawkEye both revving & idling is 14.0 +- 0.15v so this do not change @ idle but the driver demand supply voltage when it is revving moves with the pedal, but once the management light comes on this voltage drops to 0v & does not move & the pedal is then unresponsive so it looks like the ECU is removing the power when the light comes on. This is also when the driver demand fault is displayed as well, with it revving straight after you start it there are no demand faults, it is only after it goes back to idle it all goes wrong.

When I get more time I will go through all of the wiring & have a look @ the wiring diagram and see what I can find else where in the system.

I am getting closer, the fault is now intermittent, but I have not yet been able to nail the issue.

I started with the instrument cluster, there are 2 main plugs to the cluster PCB I removed them & it made not difference, so I pulled out the PCB & inspected it & it looks ok, no burning or anything that looks like it could be an issue, so I then started checking & cleaning the plugs in the engine bay & dash, some where along the line I have moved or disturbed the problem as it is now intermittent. I can start it about 10 times in a row without any dramas then out of know where the fault comes back again, tomorrow I will keep going with disconnecting & cleaning plugs in hope of finding the culprit, but at least there is light at the end of the tunnel.

I also noted that the voltage as sense by HawkEye with the engine is now dropping down to about 13.5v & almost down to 13.2-12.9v with heavy electrical loads such as the aircon on, but the main battery voltage checked with the meter is always just above 14v, or dips slightly lower when the load comes on then recovers to about 14.1v.

How is it going Col found anything more?

It is going backwards mate, as mentioned above it was running fine from time to time, yesterday it seemed to be running well so I put it back together so I could take it for a test drive but once I started it for a drive the fault was back worse than ever, I now have about 5 or 6 driver demand faults as well as ambient pressure sensor faults.

I ran a meter over the plug @ the pedal & it does not look good, the 2 x 5v supplies are now down to 0.1v and worse still when you check them to earth there is a short, they are showing the same resistance as the 2 x earths, the 3 track wires are now also showing between 130-180 Kohms resistance to earth, so somewhere along the line I have a major short. Someone else will know better than I do but I am guessing it maybe the ECU power supply is going to ground.

I will send the ECU over to the UK for testing & replace it if required as I am now going in circles. I popped the lid on the ECU again to see if there was any change & it still looks & smells the same inside.

Col
The AAP has a common source with the 5 V feed on the Potentiometer
This is what I read in another post anyway
This is likely a hint as to the issue
Based on this its possible that sending the ECU to the UK will not fix it.

I would be pretty much over it by now

Thanks mate, I have pretty well had a gut full of it now and just want the thing to work.

Without having another ECU to try it with I am going in circles not knowing if the fault is in the ECU or vehicle itself, that is one of the reasons I want to send the ECU to the UK to confirm if it is either good or bad, then I can go from there, as it is now I have no idea what to check next. :(

Hi Col, I am not familiar with mail procedures etc to Dubai but I may still have a spare EU2 known good working ECU you are welcome to borrow?

JC

Hi Justin, thanks for the offer it is greatly appreciated.

If I was in OZ I would jump at the offer but to send it internationally twice & clear customs twice especially back into OZ being a used unit is probably a bit to hard. Thanks again for your kind offer.

I will bite the bullet & send mine to the UK next week.

Quote:

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Originally Posted by djam1

Col
The AAP has a common source with the 5 V feed on the Potentiometer
This is what I read in another post anyway
This is likely a hint as to the issue
Based on this its possible that sending the ECU to the UK will not fix it.

I would be pretty much over it by now

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I just checked & there is 5v @ the AAP, so it is not the power supply, but I am still no closer to knowing what it is.

At times like these I with I had my 200 tdi back.

Col
This is what the thread said

The second, which is more common, is the loss of the 5v feed to the throttle pot. This same feed also goes to the map and maf sensors. Ideally you want to pop it on a diagnostic or else get your multi meter out to check for the feed. Chafed, exposed wires shorting are the usual reason for this issue.

I was wrong its not he aap but the map and the maf (do you get the to earth reading on the feed to the map and the maf)

If you look at the wiring diagram this is not particularly logical unless the feed to the ECU for the map and maf and the pot is common
Maybe you are right it could be the ECU

Do the 5V feeds read a short if you disconnect the 2 plugs from the ECU? This may prove the ECU is faulty