TT has been laid up since the start of December due to lockdown and MOT being due. Three decent rounds of snowfall left the poor thing under half a foot of snow for around 3 weeks in total, and it looks like this has taken its toll on the electrics.
Came to start it last weekend only for a host of electrical issues to manifest themselves, kind of made better with a decent jolt from my jump start pack. The battery had been on charge at least once a week since it was laid up, but still only showed 12.41v peak, and looked like it was draining within 48hrs, so likely shafted.
Bought a new battery but some electrical gremlins remained, and it still wouldn’t always start, nor would VCDS always communicate with the ECU.
Fast forward to today and I took the ECU out to take a look at the wiring loom and the ECU. Not helped by the fact that 2002 onwards TTs have the ECU caged inside an anti-tamper casing, sealed with thread-locked shear bolts, it took almost an hour plus a home-made nozzle for my hot-air station to finally free the ECU.
Upon removing one of the two connectors it became pretty obvious that there had been water ingress to the loom, which looks to have crept up the loom tape and saturated the connector. One of the ECU pins came off with the connector, damn.
I decided that ultimately a replacement ECU is likely to be the fix, but didn’t want to order one only to find the loom was toast too, so spliced into the missing pin’s corresponding wire on the loom, added a female dupont connector, then added a male dupont connector onto a bodge wire to the pin on the board. Re-sealed the ECU, refitted and gave it a shot, success.
So next weekends job is to renew all the suspect looking contacts in the loom connector, and order an ECU.