How does a stock temp gauge work?

[Tomsriv]

I looked at the wiring diagrams and they are all for idiot light trucks. I have a pink wire and a green wire coming off the gauge cluster I am swapping into my truck. My truck is missing the original wiring for the sender, so I can't go by whats there.
I assume one wire takes power from the dash and the other wire goes to the sender. Can someone with a stock gauge setup tell me what color the wire is to the sender?

Thanks

[protrash64]

..........I'm dealing w/ a similar situation........I believe it is green; not sure the guage of wire.

The power runs to the engine and the sender grounds, I believe.

I cleaned up a wire mess in my 64'burb and some how messed up the wire from the engine to the guage............the wire coming off my sender is dark green. I cant find where to tie it in to the harness, but my guage has the same stuff as yours; pink and green at the guage and the green disappears into a harness that plugs in above the column.

I would like my stock temp guage to work........perhaps someone could chime in.....THANKS

[Tomsriv]

Thanks, dark green answers the main part of my question. I assume a certain resistance is in the sender when it is cold and it changes when it is hot. So maybe the power comes from the pink wire, to the gauge and depending on how good a ground it has, or how much resistance to ground, that is the display of the temp? Maybe their is an expert on this board, or maybe I should go over to howstuffworks.com.

[greg64]

Here's what I know.... the gauge has 3 wires. One goes to switched ignition, one to gnd and the 3rd goes to the sender. This one is dark green, 18 gauge. The sender grounds through the engine for the return path. If you look at the back of the cluster, you should be able to identify each of the three wires, since the power and ground are used by many other things. Alternatively, if you use a meter to measure from the sender wire to ground, it should read a high resistance when the engine is cold (thousands).

[protrash64]

Greg64.......my guage is exactly as Tomsriv described. GM color code tells me pink is power and green is some type of "info" . If the sender grounds you cannot have another ground or it would short the circuit; in this case making the guage read one way or another. The third wire is the lite for the guage, Ibelieve.

Not trying to jack the thread Tom; but in my case I need to connect the sender to the harness and cant find the other end after the harness connector on top the steering column. Perhaps I should just splice into the harness right at the back of the guage. I will test this for power before doing so; then re-run my wire out to the engine.

My guage originally worked before I re-did the starter harness which was a complete mess. I eliminated everything to feed my HEI. I did not believe that the temp seder ran thru that harness.......maybe I was wrong.