Voltage at Coolant Temp Sensor
10-12-2003, 01:18 AM
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Voltage at Coolant Temp Sensor
On my 1994 GTS, Auto, US, the temperature coolant gauge is erratic and often reads with the needle all the way to the left. It occasionally goes up to 170 degrees and then bounces around and then back to the far left.
I measure only 2.9volts with the key on, but the engine not started; at both the sensor and at the wiring loom (WL1 pin 3) that is the multiple pin plug in the engine compartment. Grounds measure fine at both the connector at the sensor and at the wiring loom (WL1 pin 5).
This seems like too low of voltage. Does anyone know what it should be reading? It looks like the voltage source goes through the instrument cluster, through the temperature gauge and then to the sensor. Should I be looking at one of the fuses?
If this isn't an electrical problem, it seems like the sensor is considerably easier to replace rather than the gauge. Any suggestions?
I measure only 2.9volts with the key on, but the engine not started; at both the sensor and at the wiring loom (WL1 pin 3) that is the multiple pin plug in the engine compartment. Grounds measure fine at both the connector at the sensor and at the wiring loom (WL1 pin 5).
This seems like too low of voltage. Does anyone know what it should be reading? It looks like the voltage source goes through the instrument cluster, through the temperature gauge and then to the sensor. Should I be looking at one of the fuses?
If this isn't an electrical problem, it seems like the sensor is considerably easier to replace rather than the gauge. Any suggestions?
10-28-2007, 10:39 PM
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fwiw, I have same the intermitant issue with my GTS. I have replaced the sensor and that changed nothing.
10-29-2007, 01:25 AM
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Had a Sharktoberfest discussion about this issue on a '94. Sensor read OK (a little over 100 ohms at ambinet there) but no movement on the gauge as the coolant warmed up. Jim Bailey pulled an instrument cluster from stock and showed us how the various pieces of the digital cluster fit together. There are several places in the assembly where the signal might be interrupted.
The temp sensor is a thermistor, so trouibleshooting with a voltmeter needs to be done with te thermistor in the circuit. The voltage you read will vary based on the coolant temp of course, but at least you'll be able to see if the sense power is good and the wiring is intact for it. The instrument cluster is $k, so some troubleshooting might be worthwhile.
The temp sensor is a thermistor, so trouibleshooting with a voltmeter needs to be done with te thermistor in the circuit. The voltage you read will vary based on the coolant temp of course, but at least you'll be able to see if the sense power is good and the wiring is intact for it. The instrument cluster is $k, so some troubleshooting might be worthwhile.