First time poster, didn't see anything like this in the FAQ so hope this is appropriate:

I recently got a 1983 XLT that has been on a farm for a long time. Runs and drives beautifully but none of the gauges in the instrument panel work - EXCEPT the oil gauge, which moves from the far left up into the middle of the range when I start the truck. No speedo, no gas gauges, no temp gauge, no odometer.

I've checked all the fuses, so I'm wondering what to move on to next. Does this sound like a instrument panel voltage regulator issue? It seems weird that the oil would still work. If anybody could point me in the direction of a test to do, or another part to look at before I start ordering stuff on Rockauto, I'd be much obliged.

Edit: to be clear, I'm most interested in getting the speedometer working.

 

Speedo and odometer most likely a cable issue. Locate yours and check it.

Fuel guages don't work at all? Where do they read key off and key on? Likely it's your sending units in the tanks.

Temperature check and clean the sending unit connection on the engine first step. May need to replace the sending unit. Where does it read key off cold, key on cold and running and warmed up?

 

So if I'm looking to replace the speedometer cable, I know its two pieces: the E0TZ 9A820-F for the upper (I have cruise control) and then...how do I figure out which for the lower? I tried reading the Garage Mahal page but I couldn't make heads of tails of the tables - my door sticker says the transmission is code "K" so I think that's the C6?

 

did you check the circuit ribbon ???

 

No, that never occurred to me - does that just connect on the back on the instrument panel? What would I be looking for?

Thanks, great new idea.

 

The speedometer is purely mechanical. No electrical to it at all except the lights to light it up at night.

Why not take the cable apart at the cruise sensor, and then twirl the center piece with your fingers and see if the speedometer needle moves?

 

Yep that is the easy way to check the speedo.
If you have a helper you can pull the cable from the other side of the cruise and from the transmission and do the same, spin the cable and see if it spins at the other end.
You did not say what trans you have but with the cable out of the trans what shape dose the gear on the cable (driven gear) look like and look into the trans at that gear (drive gear).
I have had a T18 both gears were bad and a NP435 the drive gear bad.

If the oil gauge is working then most likely the IVR is goodas would be the fuse.
To test the gas, temp & oil gauges if not not working the first thing to do is find the senders and make sure the wires are connected.
Then take the wire to the sender and put it to a good ground. If everything from that wire to the gauge is good the gauge should move.
Do not leave the key on to long to have the gauges pegged as they can get hurt.
You can also use a test light on the wire you pulled off the sender. With the key on the light should blink if all is good between the wire& gauge.
If the gauge dose move then the sender is bad and needs to be replaced.

If the gauge does not move then you will need to start digging deeper of why it does not work.
For the fuel gauge do you have dual tanks? If so it could be the dash switch as the gauge goes through it before going to the tanks.
Also between the trucks main harness and the rear harness there is a plug that joins the 2 together that is below the brake booster.
This plug could have a bad connection. Could check at this plug for the blinking test light too.

The last thing would be to pull the gauge cluster and check the plug & gauge connections and the printed board.
If the board is in good shape you can clean the board with fine sand paper and see if that fixes it.
Dave ----