Temp Gauge Fix

[RMBLFSH]

First let me say that I did search this site and perused several posts on trouble shooting an inoperable Temp gauge, but did not find anyone trying to do what I would like to do.

My 1972 truck has a newer crate motor and a factory tach dash.
The Temp gauge is not working.
I have the wiring schematic, but can't seem to find the correct green wire that is supposed to connect to the sending unit, so here is my question:

Can I simply run a wire from the sending unit to the one of the 4 electical posts that I can see on the back of the instrument cluster behind the Temp gauge?

The 4 posts are oriented in the shape of a diamond.
The top post has 6.6 volts with the key on, the two "side" posts have battery voltage with the key on, and the bottom post has no volts.
None of them have any voltage with the key off.

If this is possible, whcih post should I connect to?

Thanks,

Rich

[VetteVet]

The gauge is mounted in the cluster and the circuit board provides the connections. Looking at the back of the gauge as in the picture below, The left terminal is where the green wire from the sending unit goes and the right terminal is for the power wire 12 volts.
The left circuit strip is run from the no. 6 pin on the dash connection and the right strip is run to the power wire at no.3 on the connector. If you look at the harness plug you can see the small nos. on the plug. Look for a dark green wire on the no.6 pin on the plug and the power wire will be a pink wire at no.3. The pink wire also feeds the fuel gauge.

If you wanted to run the green wire from the sender you can as long as you connect it to the left terminal on the gauge.The top and bottom terminal or studs if you want do not have any connections but the bottom stud may be grounded to the cluster and the cluster must be grounded to the dash.
after you have sorted this all out then turn the key on and ground the green sending wire and the gauge should go to full hot.

[RMBLFSH]

Dude, your text and illustration ROCK!

But I am seeing battery voltage on both the left and right terminals, and about 6.6 volts on the top terminal.
No wonder the gauge doesn't work.

Back to the drawing board...

[Tillik]

Subscribed. Damn nicely defined. Thx

[Andy4639]

This Dude does know his stuff and yes he does ROCK!

[RMBLFSH]

So I think my guage is working, but it is not moving the needle enough.

My guess is the later model temp sender is not exactly compatible with the '72 gauge.
I purchased a '72 sender, unfortunately it is a different thread size.

Is there something I can do to make the gauge read hotter?


Thanks again for all the help.

[FirstOwner69]

Originally Posted by RMBLFSH

So I think my guage is working, but it is not moving the needle enough.

My guess is the later model temp sender is not exactly compatible with the '72 gauge.
I purchased a '72 sender, unfortunately it is a different thread size.

Is there something I can do to make the gauge read hotter?


Thanks again for all the help.

Read this thread, especially post 19 by brian mac. I think he's who I sent my sender to last year.