Electrical gremlins: a Speedometer and Radio story

[Freude am Fahren]

Folks,

I have an intermittent speedometer/radio problem on my 1991 325iC. Basically, about 30 percent of the times everything works as it should. Other 70 percent of the times, when I turn on the car, the radio won't switch on (even if I turn it on with the knob turned clockwise) and my speedometer is dead even when at speed. On rare occasions, the radio/speedometer come on in the midst of the drive or go out in the midst of a drive. I realize this is perhaps a loose connection issue involving both the speedo and the radio but is there a common wire that feeds these two units? The radio is the stock unit on the car and so is the cluster.

Everything else works on my instrument cluster and HVAC panel if you're wondering.

Any info on this topic is much appreciated.

[Freude am Fahren]

bueller

[Freude am Fahren]

Truth is out there.

[Freude am Fahren]

Somebody must know the answer. Come on R3V, make me proud.

[Freude am Fahren]

help

[Cephas]

Sorry, I can't be of much help - but as a starting point, you should trace the grounds back to their respective spots and clean/reattach them. This sounds like a grounding issue to me.

[Gregs///M]

Replace fuse 10 ,12 and 21 and you may find your problems go away. Dont bother checking your fuses, just replace those 30 year old fuses.

[Freude am Fahren]

I should mention that the radio memory does NOT get wiped after one of those times when the radio/speedometer won't come on after turning on the car. This suggests that whatever power source supplied to the radio to keep it from wiping its memory is there but whatever power source it needs to operate is not. If I press any buttons on the radio while it's off but the car is on it will beep as if I'm trying to steal the damn thing. The beeping won't seize unless I turn off the car and turn it back on.

The fuse trick mentioned above was tried and yielded nothing.