Tach, OBC and stereo not working

[Wille30]

I have an 89 325ix and I am having some dash issues. I think it’s a ground, but I don’t know where this ground is…

I was driving down a very long bumpy road, which caused some fairly aggressive vibrations through the car. Everything seemed fine except the next day my head unit starts turning on and and off and on and off, which continues for a while, then it worked for a few days, then nothing, then worked etc. My tach did the exact same thing, worked didn’t work, worked didn’t work etc. And now my OBC stopped working completely as well as the head unit. So the tack just bounces around violently and the OBC and Head unit don’t work.

I checked the fuses were in securely, however I think it’s the ground. Are those 3 things on a common ground that may have come loose? Has anyone had this issue?

[b-rad]

Check antenna ground... I think it's using that ground for radio... Not 100%


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[SecludedPlayer2]

Check the ground connection under your steering wheel just above the brake pedal, a lot of stuff is grounded there. Also I had a similar issue and it did happen to be a fuse, I looked at it and it seemed fine but I replaced it anyway and everything worked. Upon further inspection of old fuse it had a hair line crack in it.

[efficient]

Try wiggling the set of wires behind the cluster ,the blue one behind the gas gauge. That connects the obc and the speedometer.

[Wille30]

Thanks guys! I will try tonight!

[IceWhite]

Check the oil pan to frame rail ground.

[Gregs///M]

Those are all good suggestions above.

I suggest you replace all those old fuses with new ones. Old fuses can oxidize and lead to poor and intermittent connection.

[e30onBBSs]

I believe fuse 10 runs all those systems and probably is intermittent or kinda broken like someone else said. Mine took a poop when the reverse light switch shorted out the fuse and a new fuse + better wiring everything worked again.

[Wille30]

Thanks for the above suggestions. I tested the ground for the stereo and it is good. I know this because when I test the 12V switched wire coming into the stereo I get 12ish V, and when I do the constant 12V wire I get between 2.3V and 3.3V using the ground wire as my ground for the multimeter. Originally I figured it was the fuse(#21), however when I switched that with another fuse I got the exact same reading. It still seems to me that the problem is originating at the fuse box because so many instruments are affected. I thought it may have been the noise supressor, but I am still reading the same low voltage if I test the input. Could the noise supressor be messing up everything it is connected to? I just wouldn't think it would affect the input voltage, only the output if there was something wrong with it.