OBC: Fuel and Speed

[Mr Project]

I just gotta ask one more stupid question, you did the speed test with the car moving, right? It will show 0v at a stop.

If it's showing 0v while moving, then you've found the problem, which is that the OBC isn't getting the speed reading. If you're sure the wire is good from the cluster, then I guess you're stuck with something being wrong in the cluster itself. I'd start by replacing the famous capacitors since they're a known issue (and cheap), resolder any bad-looking connections on the board, and then worry about detailed troubleshooting of the board afterwards if that doesn't fix it.

[RichG]

I'd start by replacing the famous capacitors since they're a known issue (and cheap), resolder any bad-looking connections on the board , and then worry about detailed troubleshooting of the board afterwards if that doesn't fix it.

I have a stock (as far as I know) 1990 525i and have the exact problems Karl1171 is describing. Speedo, outside temp, fuel gauge, clock all work, but mileage computations and cruise control don't. Not sure if cruise is related, but if it's not computing avg fuel etc. it seems it's not getting some signal about current speed even though the speedo is working.

What and where are the famous capacitors and which board could need resoldering?

Thanks