'89 535i instrument cluster odometer light stays on after car shut down and key out

[Dash01]

Just the odometer section of the instrument cluster stays lit after shutdown/key out, so where and how is that energized? How how to fix it?

[shogun]

probably a stuck check control button. First try to pull the button out. If that does not help, open the cluster and turn the rubber that is on the inside of the button, pull off and turn, then put back on, it is a conductive rubber with 4mm thickness, which becomes hard over time and loses the contact layer. Clean the area on the board which touches the conductive rubber.

from other sites: Clean the area under the button https://www.m5board.com/threads/odometer-light-staying-on.199770/
quote: just a quick update on the odometer light. After all your help I took the cluster to bits and found the corrosion in exactly the same parts as the pictures showed. I removed the buttons from the board, gave it a good clean up and then resoldered them on again. Initially all was well but as this was what it had done before I thought I should leave it for a while before confirming a fix. I've been away on holiday so that gave it time to re-appear if it was going to and I am glad to report that all is well and the light has stayed off!

how to disassemble https://www.bmwe34.net/E34main/Maintenance/Electrical/Capacitors.htm

[bimmer@15]

If it doesnt work i have a gauge cluster out of an 89 535i

Sent from my LG-US998 using Tapatalk

[Dash01]

probably a stuck check control button. First try to pull the button out. If that does not help, open the cluster and turn the rubber that is on the inside of the button, pull off and turn, then put back on, it is a conductive rubber with 4mm thickness, which becomes hard over time and loses the contact layer. Clean the area on the board which touches the conductive rubber.

from other sites: Clean the area under the button https://www.m5board.com/threads/odometer-light-staying-on.199770/
quote: just a quick update on the odometer light. After all your help I took the cluster to bits and found the corrosion in exactly the same parts as the pictures showed. I removed the buttons from the board, gave it a good clean up and then resoldered them on again. Initially all was well but as this was what it had done before I thought I should leave it for a while before confirming a fix. I've been away on holiday so that gave it time to re-appear if it was going to and I am glad to report that all is well and the light has stayed off!

how to disassemble https://www.bmwe34.net/E34main/Maintenance/Electrical/Capacitors.htm

Thanks again, Shogun!

As usual, you are exactly right: Your pictures from the m5board look just like what I found in my instrument cluster, and cleaning with my fingernail and some electronic cleaner, plus a bit of lithium grease fixed the problem.

Those who do this should know that removal of the steering wheel is not necessary--just remove the kick panel and 2 bolts that hold up the steering column, and the steering column will drop far enough to work the cluster out of the dashboard by tilting the cluster back so its upper portion fits between the steering wheel spokes at 10 and 2 o'clock.

[shogun]

Thanks for the feedback, I love a story with a happy ending, did you make some pics?

[Dash01]

No pics are needed because the pics you posted above show the exact same thing: A bit of white/tan colored crud around the two black plastic posts where the button shafts go. My procedure was to spray some electronic contact cleaner on them and surrounding ICB, pull the black plastic posts off the ICB, and clean with an old toothbrush and a fingernail. Add a drop of lithium grease to each. Replace. Reassemble cluster, install in car, good to go.

The white/tan colored crud looks like the same stuff that grows on battery terminals, but here the crud seems to cause a short circuit such that the odometer light stays on all night after engine shutdown, draining the battery. How that crud conducts electricity to light the odometer is a mystery, but that's what seems to happen.

Thank you again, Shogun, especially as once again you've helped another BMW guy, with the best advice in quick and efficient manner. This repair cost me very little time and no expense beyond about 2 cents of cleaner spray. This is as good as it gets for fixing an otherwise mysterious problem in a 33 year old car.