Temp gauge help.
Thread Starter
Instructor
Joined: Apr 2004
Posts: 231
Likes: 10
From: Billings Montana
Temp gauge help.
Just bought a nice 55,000 mile 91' coupe. Water temp gauge does not work all the time. It will work for a minute and then next time you look it is dead. Sending unit? if so, where is it located? or is it controlled by the ECM? 
Safety Car
Joined: Oct 2002
Posts: 3,991
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From: Phoenix AZ
Originally Posted by vetteman1100
Just bought a nice 55,000 mile 91' coupe. Water temp gauge does not work all the time. It will work for a minute and then next time you look it is dead. Sending unit? if so, where is it located? or is it controlled by the ECM?
Thread Starter
Instructor
Joined: Apr 2004
Posts: 231
Likes: 10
From: Billings Montana
Originally Posted by vetteman1100
Just bought a nice 55,000 mile 91' coupe. Water temp gauge does not work all the time. It will work for a minute and then next time you look it is dead. Sending unit? if so, where is it located? or is it controlled by the ECM?
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Which of the guages are you referring to, the digital one or the anolog one? They both read from different sensors.
Whichever one it is, if it is intermittant I would check the connector behind the instrument panel that the instrument panel plugs into. Sometimes these become loose where they are clipped into the plastic part of the dash behind the IP and vibration can cause one or more of the pins to lose contact.
Jerris
Whichever one it is, if it is intermittant I would check the connector behind the instrument panel that the instrument panel plugs into. Sometimes these become loose where they are clipped into the plastic part of the dash behind the IP and vibration can cause one or more of the pins to lose contact.
Jerris
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
As above - analog is from the right head. Pull the connector - gage should read LO - ground the connector and it should max out. If it does both, you need a new sender or a new connector. Senders are usually available at NAPA - make it clear you want the analog gage and not the Coolant Temp Sensor. They also have some of the Weatherpak Connectors. I find that Pep Boys has a much larger selection. You will lose some coolant if you replace the sender, so make sure you have some on hand.
If the gage didn't peg high or low, you'll need to ohm out the wire between the connector and the dash. If ok, you need a new display.
Digital is from the Coolant Temp Sensor on the front of the engine below the throttle body. If the sensor was bad or the wiring had high resistance or was momentarily open or shorted to ground, it wouldn't run very well and under the latter two conditions, it would set a trouble code. To check it out, you'll need a scanner.
If the gage didn't peg high or low, you'll need to ohm out the wire between the connector and the dash. If ok, you need a new display.
Digital is from the Coolant Temp Sensor on the front of the engine below the throttle body. If the sensor was bad or the wiring had high resistance or was momentarily open or shorted to ground, it wouldn't run very well and under the latter two conditions, it would set a trouble code. To check it out, you'll need a scanner.
Thread Starter
Instructor
Joined: Apr 2004
Posts: 231
Likes: 10
From: Billings Montana
Originally Posted by Jerris
Which of the guages are you referring to, the digital one or the anolog one? They both read from different sensors.
Whichever one it is, if it is intermittant I would check the connector behind the instrument panel that the instrument panel plugs into. Sometimes these become loose where they are clipped into the plastic part of the dash behind the IP and vibration can cause one or more of the pins to lose contact.
Jerris
Whichever one it is, if it is intermittant I would check the connector behind the instrument panel that the instrument panel plugs into. Sometimes these become loose where they are clipped into the plastic part of the dash behind the IP and vibration can cause one or more of the pins to lose contact.
Jerris
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Burning Brakes
Joined: Nov 2005
Posts: 848
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From: 1992 LT1 6 speed Cayman Islands
Are you sure?
Originally Posted by vetteman1100
91' only has analog gauge. I should also mention that the water temp is the only one not working, all others work fine.
Are you sure about this?
On my 92 there is a digital guage available by pressing the "guages" button on the DIC.
Howeber I suppose if you are only aware of the analog one, then this is the one you are talking about and the sender is the one shown in the above picture located under the exhause manifold. Remove the wire from this sender and ground it, guage should read full hot. If guage reads full hot when wire is grounded then the problem is the sender. Replace it.
If the guage does not respond when grounded, the problem is the wireing between the sender and the guage or the guage itself.
Jerris
