ok, so I guess the subject line says it all. i pulled my instrument cluster saturday. took out the TCB and resoldered it, cleaned all the connectors, tightened the mounting nuts for the fueland temp gauges, etc. put it all back together, and NOTHING. assuming that nothing got messed up in the process, any ideas as to what else it could be?

one other thing. . .what are some of the (non-functional) lights for in my instrument cluster. i saw three. on was green and had a "5" on it. i figured that was for the m46's overdrive. there was something that looked like a choke symbol, as well as something else i could make out. had some curves or something. this isn't really important, i'm just curious.

You could always remove the TCB and solder in a jumper- eliminating the TCB all together.

Randy

been thinking about it.
i saw that post in the archives. how does it affect the gauge output?

I didn't see any difference in gauge performance, but I've heard that it sometimes creates a "swing" in the gauge- ie it shows normal flucuation in engine temperatures. I can't give credit to the person who originally posted the process of installing the jumper as I don't have his name:

After evaluating and tracing the entire circuits of the temperature gauge and the temperature compensation board, here is the solution for eliminating the board entirely from the system. This will make the gauge more accurate and allow it to fluctuate precisely with the engine temperature.
Note also that this was done after doing the "don foster" fix (new op-amp and transistor), which was unsucessful.
Remove the display panel, and remove the cover (unscrew and unplug the voltage regulator, and remove the front window panel)
You should be able to see the infamous temperature compensation board on the lower right. Unplug it.
for reference's sake, assume the following numbering for the pins. Looking down at the display (speedometer should be facing you and in the middle), the furthest pin to the left is ONE, then two three and four. (These are the pins that normally connect into the temp-comp board)
Solder a wire from pin 1 to pin 3 to bridge past the tempcomp board.
Now, for all of those who are wondering how this works. Power goes into both the gas gauge and the temp gauge from pin 4 (which comes from the voltage regulator). this power runs three places: both gauges and the tempcomp board. Since both gauges are still powered from the printed wire that powers pin 4, disconnecting the board does not affect power into the gauges. Pin three runs to the wiring harness that runs directly to the temperature sender-- a temperature-varying resistor on the block. Pin 2 is an internal ground for the operational amplifier on the tempcomp board. Since you now do not have a temperature compensation board in your dash, this pin is now irrelevant. Pin one recieves current after it has passed through the gauge but before it has made it to the temp-sender. Therefore, by connecting pin1 to pin3, you safely eliminate the ever failing temperature compensation board from your system.

Find the connection at the sensor (under intake header #2) and disconnect it. Then ground the wire. See if the gauge pegs upward.
--
Don Foster (near Cape Cod, MA)

I tried it, and. . .
the temp gauge toyed with me. started going upward, then did the "TCB shuffle," by going up halfway, stopping then turning back down. Looks like i'm pulling the instrument cluster again. this time, i'm hitting the upullit and getting a few more tcb's just to try.

the question that i have. when i grounded the sensor connection (like you said), i saw another connector and wire there. it was a little below and diagonal to the one i pulled. (i ended up testing both, just to be sure) The lower one was orange, upper was yellow. any idea what this one does?

thanks

You're sure you're at the right temp sensor? Under intake #2, single wire sensor, yellow wire? If you saw two wires, you could be fiddling with the FI sensor by mistake.

When the (gauge) sensor is at very high resistance (like infinite ohms), it tells the gauge it's cold. When the sensor is at very low resistance (like grounded, zero ohms) it tells the gauge it's very hot.

"...'TCB shuffle,' by going up halfway, stopping then turning back down..."

Hmm.... This could be bad parts on the comp board. If it were mine, I'd drop in a new IC and transistor (got a bag of 'em). This has worked for me, but others tried it unsuccessfully. It could be that they did it wrong, that they couldn't solder, that the parts were bad (or wrong), or that the problem was elsewhere.

"Looks like i'm pulling the instrument cluster again..."

Good thing it only takes 90 seconds....;-)

On an '87 car, be very alert for a bad engine harness, which includes the single yellow wire to the temperature sensor.
--
Don Foster (near Cape Cod, MA)