Temperature Guage

[stope4]

My temperature guage does not record a temperature when truck is warm. I replaced the sender, still nothing. I measured 12 volts at each terminal at back of guage when truck is running so I think the the printed circuit is good. How can I tell if the little resistor on back of guage is working? Should the guage panel be grounded to something?

[Longhorn Man]

t grounded, you'd be complaining about lights and fuel guage not working properly, they are always the first to act up.
Odds are, if you were to follow the green wire that goes to the sending unit, you'll find it melted or cut or something. If there is no obviouse damage, unplug it from the sender, and with the ignition switch in the run position, ground the wire to the engine block, or even with a jumper to the neg post of the battery. Look at your guage, if it is peddeg out, then the problem is in the sender and or actually not warming up properly.
If it does not react, then you need to troubleshoot it, and you've already done most of that already.

[stope4]

O.K. I undid the wiring and checked it all the way to firewall box. No cuts. I changed the resistor on back of guage and now the guage pegs all the way right. What resistor am I suppose to have? The temperature guage is new from local auto parts house. And it is for guages.

[byrd]

The new aftermarket temp gauges do not need the resistor that I have seen they are built in now. The resistor you need for the old temp gauge is around 56 ohms. Randy

[stope4]

It's an original temp guage. I have two resistors one has a wire wrapped around some kind of board (like the one for the fuel guage). The other is ceramic looking. Will either work if ohms are good?

[Longhorn Man]

If you are pegged, (assuming your resisters are all good) your green wire would be shorted to ground... like melted on an exhaust manifold, or a faulty sender (even though it's new, it can be faulty)

[stope4]

Success! I changed the resistor from the ceramic to the wire type and wala. The guage works.

Longhorn, I checked the wiring really good last evening and there were no cuts or melted places. I cut the connector off because I thought it was loose and spliced in a new one. Tried the ceramic resistor last evening and got a pegged guage. Tonight, just for grins, I changed the resistors, and what do you know, the guage works. I don't have an answer other than I was certain the green wire wasn't shorting out. But at the same time, I agree that the pegged guage meant a short. Maybe the ceramic resistor has a short in it.

[Longhorn Man]

Either way, your guage works now.

[byrd]

The resistor had gone bad, which made for infinite(sp) resistance pegging the gauge, not the 56 or so ohms required for the gauge to work properly.