Temperature Gauge Inop

[PhyrPh0enix]

1972 F-250 360/Auto
I JUST got the truck and I've driven it a couple times; but I'm weary, due to cooling issues, to take it out on the road if I can't tell if it's overheating. My water temp gauge (upper right) just sits on "C" and never moves. I'm wondering if it's the gauge or the sender or what...

Does anyone know any common issues with this?
Does anyone know the sender resistance values so I can diagnose it before I buy a new one?

Thanks

-Vince

[basketcase0302]

Vince,
Your 72 would have a printed circuit board like this:

Assuming all other gauges work fine...I found on a few of my dent era trucks for the printed circuit board to be the culprit in a number of different issues. And a lot of times it's simply where the harness plugs into the printed circuit board itself-connection there needs cleaned up. But I'd first ground the temperature sending unit wire, (remove it from the sender and short it to the intake manifold) with the engine running or key on while someone watches the gauge. Typically the sending unit would have failed. If your gauge moves when grounded the sending unit would be bad. Make sure you tell the parts monkey you have gauges and not an idiot light when/if you need to get one.

[PhyrPh0enix]

Thanks! Is it terribly difficult to take the cluster out? I might wanna do that anyway. My interior lights leave a lot to be desired! Better not mess with too much at once though... don't wanna cause five problems fixing one!

-Vince

[Kurt Combs]

Did your sending unit test ok?

[72BahamaBlue]

Thanks! Is it terribly difficult to take the cluster out? I might wanna do that anyway. My interior lights leave a lot to be desired! Better not mess with too much at once though... don't wanna cause five problems fixing one!

-Vince

Removing the instrument cluster is pretty quick and not too difficult. It's nice to locate any unused connectors behind the cluster, and test and tag them. Doesn't hurt to send some lube down the speedo cable housing while it's accessible.

Remove the upper and lower bezel screws, gently wiggle the cluster out a little. You may need to pull the speedo cable by reaching under the dash, it will give a couple of inches, bezel will clear the column trim piece, it can be removed first if you want.
Reach the connector, gently squeeze the electrical connector clips top and bottom, plug will pull out. Pull out the turn signal flasher if it's still attached to the cluster.
Unscrew the speedo cable nut, it should be hand tight, pull cable out from speedo head.
Cluster is free, I like to remove it towards the passenger side.

Before reinstalling, make sure the little clips for the bezel screws are intact and located. The speedo cable might not go back in unless the speedo head is spun a little to line up to the squared cable end.

If you have a burnt out light and replacing the bulb doesn't fix it, try removing the bulb from the socket and bend the 4 little tangs inside the socket in a bit.

[basketcase0302]

and now, (with the instrument panel out) would be the time to check the IPVR, (there's info here somewhere on how to do that) and the headlight switch, (instrument panel lighting portion of it.

[PhyrPh0enix]

FIXED!!! It was the sender...

I replaced all my dash lights too, and the light switch... Now it looks like a REAL truck!

-Vince