88 TC with major guage issues - RESOLVED

ok, guages havent worked since I bought the car. The tach and speedo worked, but thats it. Now after the 5 speed swap the speedo doesnt work either. I pulled the cluster to replace the IVR, replaced it and no change. I noticed on pin 7 (ignition switch), gy/yellow wire there is a smaller guage black wire tapped into the pin and goes nowhere. In my EVTM it only shows the gy/y wire and thats it. I pulled the cluster out of my friends 87, the wire goes back into the main harness, or comes from the harness. I pulled my harness as far as I could back (about a foot) and see no broken black wire that it could be from. I also noticed on the back of my cluster there is a burnt spot on the RH side of the speedo where a sping lookin thing that screws to the cluster and appears to be on the illum circuit, but it gets gets super hot... any suggestions?? I just want my guages!

aww come on, Im sure others have had guage issues on their TC. I read the FAQ's and looked everywhere and all I find is the "guage flutter and to replace the IVR"

Originally posted by 94Lightning:
ok, guages havent worked since I bought the car. The tach and speedo worked, but thats it. Now after the 5 speed swap the speedo doesnt work either.

This says to me that either something's wrong with the ESS (electronic speed sensor) in the new 5-speed transmission or it's not connected correctly.

Originally posted by 94Lightning:
I pulled the cluster to replace the IVR, replaced it and no change. I noticed on pin 7 (ignition switch), gy/yellow wire there is a smaller guage black wire tapped into the pin and goes nowhere. In my EVTM it only shows the gy/y wire and thats it. I pulled the cluster out of my friends 87, the wire goes back into the main harness, or comes from the harness. I pulled my harness as far as I could back (about a foot) and see no broken black wire that it could be from.

IIRC that's a "hanger" and it's supposed to be there. I think it's some sort of very small capacitance but I do seem to remember it. I think it's shown in the EVTM as a "dashed" (or dotted) line.

Originally posted by 94Lightning:
I also noticed on the back of my cluster there is a burnt spot on the RH side of the speedo where a sping lookin thing that screws to the cluster and appears to be on the illum circuit, but it gets gets super hot... any suggestions?? I just want my guages!

The "spring looking thing" is a resistor wire that reduces the voltage to the IVR; if it's burned out you'll have the "no gauge" problem you're seeing.

All this is from memory, my EVTM is stashed somewhere and it's been a while since I looked at it; I could be way off base here if my old-fart brain isn't working properly this morning.

BTW for everyone's edification it's G-A-U-G-E

had same problem it turned out to be a gray wire at the ignition switch (steering column)

but where does it go? I pulled the cluster in my friends similar optioned TC and it came in from the main harness but couldnt tell where it came from. Where can I get the resistor? By tracing it on the printed circut board it appeared to be on the illum circut which all seems to work ok. Either way I'm going to have to get another cluster as my printed circuit is melted under the resistor. Bhpinto, did you find a break in the wire at the column? I replaced my ignition switch and followed wires as far as I can see and it looks fine, I wonder if I may have to overlay it.

no breakage,wire was just out of connector

theres obviously breakage as out of the plug there is 2 wires one black and one gy/y out of my plug (coming from the harness) the black wire is broken. There is no black wire coming from the dash harness to CONNECT

theres obviously breakage as out of the plug there is 2 wires one black and one gy/y out of my plug (coming from the harness) the black wire is broken. There is no black wire coming from the dash harness to CONNECT to this wire. It is broken from somewhere. I pulled the cluster from my friends TC and there is the same black wire coming from the dash harness and goes to pin 7 just like mine is supposed to, sans my black wire doesnt come out of the main harness anymore. I pulled the wiring back almost a foot and no broken wire. It has to come from somewhere. At the plug it's still tapped into the gy/y wire in the factory splice just broken about 4 inches back from the plug.

oh wait, im an idiot. I just read back up on who I was replying to about the broken wire, you meant the gy/y wire was out of the connector.. I get it.. Its late and been one hell of a long day, sorry.

GY/Y wire out of ig. sw. powers the temp, oil, fuel gauges thru the IVR. That wire is a "special" resistance wire with about 8 ohms resistance from end to end. It goes into one of the pins of the big connector that connects to the cluster. I dont remember which pin, and dont have access to my EVTM right now (at work).

Speedo and tach are powered by a seperate 12V wire. If tach works, problem is likely the speedo or possibly the flex printed circuit board being open somewhere.