A8 Parts Forum - Gearbox red lights.

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Gearbox red lights.

I've not put this in the gearbox thread, because I'd like to get as many views as possible please.
I had a full, guaranteed gearbox rebuild last month (2.5K).
We've been on holiday for 2 weeks and got back to a low, but functional battery. Yesterday, I left the TV on for the kids in the car for 10 mins and the inevitable happened - it died! Started instantly when jumper cables were connected, so all good. 30 mins later ( car starts fine), I reverse out of a space and engage D - the gearbox indicator in the dash shows all reds and the gearbox goes into limp mode. I switch off the car at the lights, restart her and all is good. Not been a problem since.
Last time I had all reds, it was the usual warning before terminal issues killed the 'box. It's under warranty, so i want to warn the garage that it's playing up again.

My question is: Can electronic gremlins after a battery drama cause the gearbox ECU or solenoids to play up? To me, this is feasible, as the car "sets itself" again. If not, I need to register the glitch and get her back in for a health check!

Any experience of this please?

Quote:

Originally Posted by jmw748 (Post 5093)

I've no direct experience of this happening, but it sounds plausible.... The gearbox recon is a very mechanical orientated process, where the ECU / dashboard is all electricery, so if its had a rebuild I'd expect it to be sound. It may be worth 'running it past' the gearbox place, if nothing else to alert them that something funny has happened, just in case it does deteriorate rapidly but unless you've got any interesting vagcom errors on the gearbox TCU I can't see there would be a lot they could do unless it 'breaks' completely....

As stated above, mention it to them and worth a quick fault check but if the battery has been flat the gearbox (and any other) ECU can lose it's basic settings. This means it has to "learn" all travel stops of actuators and sensors before it can perform properly again. It is not uncommon to need to carry out basic settings on the diagnostic computer after a flat batt. The car can usually get around this itself but can take 30-70miles which may explain why it drove ok first off.

A quick note. If ever jump starting ALWAYS turn on all heavy consumers AFTER the flat car has been started but before disconnecting the cables. This is due to the fact that when the cables are disconnected and the system's charging there is always a small spark from the clamps. This spark can cause a voltage spike around the car's electronic systems and seriously damage ECU's!!! Any of them!