tach trouble
 

Does the tachometer run from the tcu?

Don't have my fsm but it can be wiring into the input of the ignition capacitor...

Where is this ignition capacitor located?

So i thought maybe the tcu was the issue because i swapped it. But i swapped back in the old one and tach is still not working. Being that was all i swapped i figured start with what i did because it worked before swapping the tcu. I checked to see if maybe i accidently unplugged or disturbed something in the proccess but from what i see everything appears normal. What could cause the tach to stop working and all other gauges are fine? It's a 92 vg. Any suggestions?

Have you tried tapping on the Instrument cluster? In my third gen I had to bang on the cluster to get it to work.

Lol. Funny you mention it because i suppose it's just a reaction but yes i did try tapping it though i didn't bang on it.

No, the usable signal comes from the ECM. There is a condenser circuit prior to the ECM. But your problem is a faulty tach, just replace it.

I also put in a new ecm along with the tcm and put in yet another ecm thinking it may have had something to do with it being that prior to replacing the ecm the tach was working. I had originally replaced the ecm so i could get the timing set back to normal being my other ecm was chipped by a tuner and after having the distributor adjusted it threw off the timing causing a mis. Can the tach itself be replaced without swapping the entire cluster? If so how easy is it to do without buggering up my cluster? I wasn't sure if the tach got signal from the speed sensor at the tranny or the distributor or what. I've checked for any lose or bad connections after replacing the ecm but everything appears to look o.k

Yeah, it's easy to replace that tachometer itself. Just remove the cluster, remove the fascia, and there's a couple screws on the back that hold the tachometer in place, remove those and you can swap it right out.

I removed the facia on a spare cluster I have but when doing so it looks like the gauges are thin plastic on the end of a plastic post are the screws I need to remove on the very back of the cluster where the circuit board is? Any pics. Or a diagram would be extremely helpful. I have 2 spare clusters so if something happens during removal on one of them its not a really big deal being it'll be my practice cluster so to speak. The other is an se cluster. If it's doable I'd like to swap out all 3 gauges into my vg cluster so I can still retain my factory cluster with proper mileage. Any detailed instructions would be awesome. I've tried searching but am getting a few different answers that don't sound overly simple or detailed and one involved removing the needles?

Thanks Hectic, Yes the gauges are interchangeable. I just swapped my gxe cluster with an se one and it worked. It was the tach itself. Im guessing the metal box with the 2 wires on the back of the cluster? I just swapped over my odometer so the mileage remains proper. Only one screw and it swapped over quite easily. Wasn't a crazy hard job but now i have to take it apart again to swap the led's the previous owner had in it which now look like only one or 2 out of the 4 are working. Only half of the cluster gauges are lit and it was actually pretty dim for led's IMO.