Idle gauge not working

[Joey23]

Hello everyone, not too sure if anyone had this issue in the past but I have a 1990 535I manual trans and for two weeks I was having idle issues. My RPMs will be around 2k to 3k while the car was in idles or came to a complete stop. I checked for vacuum leaks and I wasn't able to find any. After two weeks my RPM gauge stopped working. Thanks in advance to anyone that can help with this issue.

[theBMWbeast]

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

[ross1]

If your tachometer was reading correctly before failing you have either a stuck throttle, idle control valve or a significant vacuum leak. A vacuum leak that bad would probably manifest itself with other drivability problems which you don't mention.
My bet is a throttle not closing all the way, perhaps a stuck ICV. Check your throttle cable to see it returns to idle position. At this age a frayed cable hanging up in the sheath wouldn't be at all surprising. IF that is the case bear in mind it could also decide to stick at wide open throttle so best to investigate sooner rather than later.
Failed tach and a true 2-3k idle are unrelated.

[Joey23]

thanks you, I will double check this week. I was waiting for the temperature to get a little better in Texas, we had that freezing weather all last week.