GEARBOX CONTROL UNIT (ECU) ISSUES - Knowledge Required

[Yangi19]

Hi All
In need of some Knowledge from others who have experienced similar problems. (I have read other threads - but doesn't seem to cover the issue I have now)

2003 A6 ALLROAD 2.5 TDi Auto

So this is what happened.

On the daily drive this morning to the office (a 7mile journey), I noticed after about 3 miles that the PRNDS display wasn't normal - and was showing ALL GEARS selected.... ( normally pretty observant and notice when something looks/feels/or sounds different) - so I guess it wasn't like that at start of journey. But car was working as normal.

Then after another few miles, the Suspension/EPS/ABS lights came on. Travelling at 30mph I didn't notice any change in the car until pulling away from a set of traffic lights where the car was struggling. (I am guessing that when these 3 lights come on the Car is in LIMP MODE? Correct me if I wrong?). I drove the last mile or so slowly and I think the car was stuck in one gear only.

I parked up. Switched engine off. Then restarted. The Warning Lights had gone out, but the PRNDS display was same. I drove back down the road, and within half a mile the Warnings came on again. The car was starting and running okay - but obviously in a safe mode. I didn't have time to check anything, so Parked it back up and took one of the pool vehicles as I needed to go to London.

Whilst at 'work' I was able to have a basic look through the forum although couldn't log on. And obviously there were a Number of Issue that it could be. So when I returned in the afternoon I tried the car again.
Car started fine, ticked over okay, but the PRNDS display was still wrong. Putting car through RND resulted in a Harsh engagement of each move. Then after a minute the Suspension/EPS/ABS lights would come on - but the car still ticked over ok.

SO after more forum investigation and to cut a longer story shorter:
*I found the Driver carpet to be soaked underneath the Mat; and when Pulled up was surprised not to see Goldfish swimming underneath!!!
*Disconnected Battery Neg.
*Sucked Up about 3 GALLONS of water from Footwell, and Carpets Front & Rear Driver Side with Industrial hoover.
*Removed Gearbox ECU from Plastic Case
*Placed ECU in front of (a Hot) Fan Heater for about 30 mins
*Dried Wires/ECU Connector with Hair Dryer
*Dried (as much as could) the Under Carpet Foam

and after about 2 hours I plugged the ECU back in, Reconnected battery lead, and Started the car.

The car started... the PRNDS Display was still wrong, and after 30s or so the Warning Lights came on, the Engine went 'Lumpy', Hunted on revs, and then died....

I tried a few times... sometimes would not start. Then would be okay for a couple of minutes before cutting out. Other times could not get the 'Park Brake' light to go out to disengage Park. Other times could, but engine would still stop.

Have managed to move it out of way for now..... And driving a FIESTA!!!

When I found the Water Ingress Issue, and dried things out I thought I had sorted the issue.... but seem to have made things worse!!

Therefor any advice/previous knowledge would be greatly appreciated.

Kind Regards

[fishybusiness]

No expert on these, I would expect it to take much longer than 30 mins to dry out an ecu, especially as the amount of water ingress is likely longer term.

Do the top covers come off these? Thinking drying out.......

[Scott K]

Hi,

Corrected the title for you.

Not sure about the control module and drying it but you need to sort out the water ingress if you haven't already. Quite common and hopefully easily fixed.

[abby1]

Hi,

Corrected the title for you.

Not sure about the control module and drying it but you need to sort out the water ingress if you haven't already. Quite common and hopefully easily fixed.

i had that needed new ecu got one from breakers make sure same part numbers

[Yangi19]

i had that needed new ecu got one from breakers make sure same part numbers

Thanks for the input folks ....

Update: Dried Car out More (not sure I got to root of flood issue yet) And was it is starting ok and running without stalling now, But still showing errors on Gearbox PRNDS display.

Next door to work is car workshop and they have a Diagnostics that works with most vehicles. Plugged in and came up with 5 Faults on Gearbox. 1 x torque converter and 4 x Pressure valves (ie... all signals from gearbox)....

I Cleared Fault Codes and dash Display returned to normal - but gearbox still 'clunky' engaging gears.

Turned ignition off. And read codes again... 1 fault remaining on gearbox ... 02 pressure control valve, Open or Short Circuit....

Have disconnected Battery and removed ECU for further 'drying out' over weekend. Then see where we are from there.

will also investigate WHY water getting into footwell in first place??

Keep you all posted.

Many Thanks
Yangi

[fishybusiness]

Water ingress is a common fault, most probably due to the scuttle panel drains being blocked - where your wiper motor and linkage are housed.

Lift bonnet, remove scuttle plastic panel, remove battery. You'll find one drain under battery tray, the other under master cylinder/ servo area drivers side.

Clear out debris - often leaves and other crud, push a wire down both drains and ensure you go all the way down the tube, so they are clear and water can drain out again.

Some people also find the pollen filter rubber seal has perished - worth checking, take out the filter, passenger side scuttle area, check rubber seal underneath for degrading.

Clean them out once a year or so.

[Yangi19]

UPDATE: TUESDAY 9th JAN.
Thanks to all who have inputted to the issue I was having.
Just want to update everybody with a happy result and give hope to anybody suffering similar issues.
Having Disconnected battery and taken the Gearbox ECU out again Friday night , It spent 3 days drying out in a warm place (in a towel near the radiators). And with the interior of the car drying out further, I finally got around to refitting it this evening. ECU Fitted, Battery Reconnected, Switch on Ignition - and Bingo!! Dash Display (PRNDS) back to Normal. Started fine, ticked over lovely, and I ran the car through Gears whilst stationary, and the change between gears was unnoticeable.

Have since driven 10 miles home and everything working perfectly The gearbox changes seem even smoother than before....although that maybe my imagination.

Many Thanks to everybody for the advice and help.

Regards
Yangi

[fishybusiness]

Result!