Temp gauge weirdness...help?
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Senior User
Joined: Oct 2006
Posts: 299
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From: Topeka, KS
Temp gauge weirdness...help?
Need to know where to start. Finally got old mater running today, working great. My temp gauge isn't working, though. I don't have Teflon tape on the sender, heard that one already. It worked when I disassembled the truck. I have a Runtz on the back, the oil and fuel gauges work great with them. The temp gauge just jumps back and forth, then pegs to hot. I'm 99% sure I've wired it correctly. Any tips for diagnostics? Start with the sender or gauge?
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
I seem to remember, and my rememberer isn't very reliable these days 
, that if the sender is disconnected it reads full cold and if you touch the disconnected wire to ground it reads full hot.......so maybe the sender is on the fritz or the wire to it is shorting to ground.......
, that if the sender is disconnected it reads full cold and if you touch the disconnected wire to ground it reads full hot.......so maybe the sender is on the fritz or the wire to it is shorting to ground.......
Roast em' if you got 'em
Joined: Mar 2005
Posts: 22,017
Likes: 9,975
From: Rio Rancho, NM
I'd start at wherever its easier to get to, probably the sender. Pull the wire off of it and then see what the gauge does. As Sparky mentioned, see what the gauge does when you open the circuit and when you ground the circuit. If that has no effect on the guage then you have a problem in the wiring to the guage. Did you rewire the truck? aftermarket harness? original harness? Check for a short to ground where the harness goes through the firewall or at any other place where the wires could wear through.
Good luck
Bobby
Good luck
Bobby
Elder User
Joined: Sep 2003
Posts: 587
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From: Augusta, ME
If you don't find any shorts that way, do you have separate runtz resistors for each gauge? If so, swap the temp one with one of the others and see if you just got a bad resistor. The ones I have, I've always thought they look pretty fragile, with exposed diodes and doodads.
