jonpanic

Forgive me if this has been discussed, I searched but couldn't find exactly what I'm experiencing. My 87 4runner has this intermittent problem where the tach will go to around 2K RPM and just stay there. Sometimes it'll happen as soon as I put the key in the ignition and just turn on the accessory voltage. While I'm driving along and it's stuck at 2K it'll bounce a little, but it's hardly perceptible.

I took apart the dash and cleaned the electrical contacts on the back of the instrument cluster, I also cleaned the contacts at the igniter. I'm out of ideas here, could it just be a faulty instrument cluster? Or is it getting a strange electrical signal from somewhere?

Thanks for your help!

Co_94_PU

iTrader: (-1)

Both of your hypothesis are essentially the same issue.

Exactly what did you clea on the multi cluster?


What insoece did you perform while you had the cluster in the bench?

Did you inspect the cluster ground?

ev13wt

This first.

I have an issue where it will randomly show 500RMP less. GND.

ev13wt

wrong thread sorry<

jonpanic

I took the cluster out and cleaned the contacts on the back where the harness connects with electrical contact cleaner. I also cleaned the connectors on the wiring harness. How would I go about fully inspecting the cluster and the ground? I appreciate all your help.

Co_94_PU

iTrader: (-1)

You should extend your work to the nuts that hold the flexible circuit to the guage "pods'. While you have it out you want to look for damage to the tach guage. I don't have my spare on hand at the moment, buy you want to look for broken and burned bits.

The tach signal is a switching signal to ground. Assuming it uses the same deal GB as the others this switching to ground heats up a bimetal bar were moves the needle. If you grounded the tach line too long it can fry the windings.

jonpanic

Excellent, I'll give this a go. Thanks!

jonpanic

That did it! Went through every fastener that attached to the flexible pcb, loosened them and gave them a good spray with electrical contact cleaner. Then went back and snugged everything down. Seems to have done the trick!