Tach (only) not working

[jmcgill]

I just purchased a 1987 325is, and while I'm not surprised that the odometer (motometer) doesn't work, I am having issues with the tachometer not working.



I got this car from the original owner and it has had quite a few dollars put into it over the years mainly by a BMW dealer here in town.



I did some searching on the forum but couldn't find an occurrence where ONLY the tach wasn't working. My fuel economy thing works, temp gauge works, service interval lights work, onboard computer works, etc.



Am I still looking at a battery problem in the SI board, or is there some other area where I should try to look to see if I can get the tach working? If it is the SI board, I'll do the batteries when I take the cluster out to do the gears in the odometer.


Thanks!


Joe

[Powling]

I could be your fuse. Do the interior lights / dash lights work as well or not? I know I pulled my fuse for the interior lights this weekend and noticed the tach ONLY didn't work in the cluster, so give that a try and see if it works with a new fuse.

[jmcgill]

Thanks very much for the reply!



All the interior and dash lights work properly, but I'll check out that fuse anyway.

[hawaiie30]

Just went through this on my '86 325es. Did the fuse, then the SI board. When you have the SI board out, check the grounding nuts on the back.

Mine ended up being a faulty tach.

[jmcgill]

I'm leaning toward faulty tach too. My mpg gauge and service indicator lights still work, and I was reading that if the tach goes out the mpg gauge shouldn't be working either....maybe I misread.

[hawaiie30]

My econometer worked also. Just the tach itself was out.

[jmcgill]

I fixed it. Disassembled the cluster and found that the needle for the tach was stuck to the pin. I guess it sat for quite a while and needed to be loosened up. Works great now.

Unfortunately I found the reason my odometer isn’t working. There is something broken in the trip odometer reset assembly.

[jgilber0]

Yes - my odometer was not working right, even after replacing the gears.

I wound up buying a used cluster, changing the SI batteries and replacing the odometer gears. Now all is working perfectly.

[cscracker]

Yeah, the odometer gears turn to mush. There are a few different companies who sell replacement gear sets for them.