No interior lights & intermittent instruments

[tjrundy]

Hello,

my B5 went in for a 'routine' service at 121k miles recently and came out with some fresh cams, brakes, valves, sump case, pipes, brackets and an extra 0 on the end of the bill. However it also came back with 620 torques which I'm very happy with, so rough with the smooth and all that.

After driving it back from the specialist a month ago, I left it parked up for 2 weeks whilst I was away. Unfortunately my next drive was in the dark, and without much idea of how fast I was going. That's because I have no red backlights, no illuminated instruments, and dials that read for about 20 seconds before all going dead.

After start-up the ABS and ESP lights come on and the instruments read for about 20 seconds, then there's a relay click and then they go off for another 20 seconds, before the cycle repeats.

The garage suggested that I change the battery, which I did, but this didn't fix it. I also checked each of the fuses which are all fine. I've been away again so it's been sat on the drive since. It's a good 2 hours drive back to the garage, so before I head back, I wondered if it was anything that I might be able to take a look at myself.

The HVAC lights come half-on, but I read that this is powered by the CAN bus, and the electric window backlights are also on. The radio also works, but has no backlighting also. There is no DIS, and no odometer. Otherwise everything appears to work, and at least I can drive it.

I wonder if it's a bad connection somewhere between the instrument and the ECU is to blame, and is causing a bad earth / short circuit. This of course might have developed after being left in the rain for a couple of weeks. I'm an electronics engineer so I could no doubt fix it myself, but at the same time, it might just be quicker to take the trip back to the garage.

Any advice before I book it back in would be much appreciated.

Thank you, Tom.