problem with temp guage - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1968GMC · 05-04-2003, 12:30 AM

I instaled a full gauge cluster to relace my dummy light cluster. I'm having truble with my temp gauge, it reads past the H mark, and I instaled a sending unit for gauge. What could it be? Please help.

*Piston* · 05-04-2003, 12:32 AM

when you disconnect the sending unit wire at the sending unit, does the gauge move to C? If not you could either have a bad gauge, grounded signal wire (due to installation or pinched/rubbed wire)

Southpa · 05-04-2003, 05:45 AM

This has been discussed alot in this forum and I've had the same problem. I went to mechanical gauge/sensor route instead. But anyway, make sure your ground straps and connections (block to frame, frame to firewall etc.) are intact. And I've also heard that using teflon tape on the sensor might hamper the circuit.

The sensor is the variable resistance variety activated by heat, but you have to have a complete electrical circuit in the system. Take a normally working temp. system and unplug it and you will see the gauge needle peg out to the right. That means infinite resistance, ie. no current. So you might have some grounding problems.

Do an archive search on this site and you will find lots of previous input from other owners to help you out.

Longhorn Man · 05-04-2003, 10:50 AM

Look around the exhaust on the drivers side...look for a wire (green if memory serves) that may be melted to the manifold.
Then look on the fire wall where you ran teh wire, see if it is cut and grounding.
If you ground the wire, it'll peg to hot, if there is no ground at all, it'll say cold.

05-04-2003, 12:30 AM	#1
1968GMC love my truck Join Date: May 2001 Location: aylmer QC Posts: 648	problem with temp guage I instaled a full gauge cluster to relace my dummy light cluster. I'm having truble with my temp gauge, it reads past the H mark, and I instaled a sending unit for gauge. What could it be? Please help.

05-04-2003, 05:45 AM	#3
Southpa Registered User Join Date: May 2000 Location: Victoria, BC, Canada Posts: 2,410	This has been discussed alot in this forum and I've had the same problem. I went to mechanical gauge/sensor route instead. But anyway, make sure your ground straps and connections (block to frame, frame to firewall etc.) are intact. And I've also heard that using teflon tape on the sensor might hamper the circuit. The sensor is the variable resistance variety activated by heat, but you have to have a complete electrical circuit in the system. Take a normally working temp. system and unplug it and you will see the gauge needle peg out to the right. That means infinite resistance, ie. no current. So you might have some grounding problems. Do an archive search on this site and you will find lots of previous input from other owners to help you out. __________________ 1970 GMC 1500 Custom Original 350/TH350 Victoria, BC, Canada You can wish in one hand and crap in the other. See which one gets filled first. Last edited by Southpa; 05-04-2003 at 05:47 AM.

05-04-2003, 12:32 AM	#2
Piston Account Suspended Join Date: Oct 2002 Location: Olathe, KS Posts: 2,301	when you disconnect the sending unit wire at the sending unit, does the gauge move to C? If not you could either have a bad gauge, grounded signal wire (due to installation or pinched/rubbed wire)

05-04-2003, 10:50 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Look around the exhaust on the drivers side...look for a wire (green if memory serves) that may be melted to the manifold. Then look on the fire wall where you ran teh wire, see if it is cut and grounding. If you ground the wire, it'll peg to hot, if there is no ground at all, it'll say cold.



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