69 Bronco temp gauge not working

[SIO]

Hey guys 69 Bronco original gauge cluster temp gauge wont move normally. Ive red most of the posts on this issue and had done all the usual test but must be missing something. If i let the motor warm up and then turn it off and then start it back up or just turn key on the temp gauge will jump up to what looks like the right temp and slowly go down. Fuel and oil gauge working. the only issue i see is that the volts at temp gauge is about 10v. Could that be the problem? Also i know its not related put the amp meter needle just bounces and stops off and on constantly just annoying. Any ideas Thanks

 

[DirtDonk]

Hey there. Well, it seems like you’ve eliminated the IVR as the problem because your other two gauges work. But the fact that it jumps up after a restart is really strange.

You say you’ve done the tests described in other discussions. Just what have you done?

 

[SIO]

Tried a couple other temp sensors, cleaned grounds, ran aux wire to gauge from sensor, shorted out gauge it pegs out. One thing I cant remember doing is checking the ohms across the temp gauge itself. What should the ohm reading be on the gauge. Anything else i should check.

 

[DirtDonk]

So when you ground the original wire at the temperature sender, the gauge pegs?
Not the new wire, just the one that’s existing now.
If it pegs, then it would seem that the wire and gauge are working. Leaving only the actual connector at the end in question.
I suppose there’s a potential scenario where the gauge is failing and only works at the extremes. But I haven’t run into that before.

The ohm range for the system is 73 to 10.
A 10 reading would be full and 73 empty. I have heard that the gauge has the same reading, but I’m not sure how that works.
Someone else will have to describe that.
If that were the case, then with the key off and the gauge at zero, you should be reading somewhere near 73 ohms across the terminals.

Maybe the reading at the gauge terminals is supposed to be based on the resistance through the sender, with it still connected?
I’ve talked about them often enough over the years, but I’ve never actually had to test one in that scenario.

 

[Oleguy 74]

with both wires off of the gauge,10 to 15 ohms.ford spec accros gauge same with fuel and oil gauge