325 TACH & COOLANT GUAGE NOT WORKING HELP!!!!!!!!

[nite53]

Hi,
My 1986 325 tach and the coolant guage are not working. Everything else on the dash seems fine. I've read to replace the re-chargeable batteries to resolve this, but also, check fuses! Fuses are good, is replacing the batteries the right mode of searching? Is it a good possibility that the batteries are the culprit?
Also, does anyone know hte color codes for the radio connector wires? all my radio wires have been cut off!!!!
ANy help will be most appreciated.
Thank You
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[crazy cajun]

I have the same car with the same problem it turned out to be the cluster still have not fixed it yet just keep a eye on the coolant. I well look when I get home I have the book on the wiring

[bimmerman333]

most likely the circuit board , if all the service lights work , most likly need a new cluster. good luck.

[jeffreyb4me]

The S.I. board in the cluster will cause this problem as tach and temp. info go through it before the gauges, the batteries fail to but replacement rarely cures anything.

[beemer5]

it is the circuit board with the batteries in, try to find one in the junk yard, just pull out the board and push in the new one.. I think a new one is about $200, try used.

[jeffreyb4me]

yes, it is the circuit board 'with the batteries' but find a good used one is as likely as finding a good one in a non-wrecked E30 that hasn't been replaced recently. They were poorly designed and there's more to these boards than the batteries on them...[I've been repairing them for 20 years].....

[beemer5]

I am saying to replace the board, there are many of them in the junk yards, Herry's u pull it.. in PA. has many, many of them.

[jeffreyb4me]

Sorry, I was saying not to bother with another junk board, replace it with a quality remanufactured unit.

[mystermathers]

What happens when the tach works, but not the temp guage? I replaced all the sensors and still nothing? also, the coolant level lights has been on before and after I changed them?