Help! radiator fan not working
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Junior Member
Joined: Jul 2018
Posts: 1
Help! radiator fan not working
so first its a 98 ls 1.9, and the radiator fan keeps not working when it should. it isnt coming on when the temp gets up or when i kick the ac on. ac works til the car gets over warm then it blows hot. i instyalled a new ECTS and it seemed to be kicking on and off fine, now 12 hrs later its not coming on again. relat is kicking out 12v, and the fan works when i put power to it. so is thee another switch or sensor that tells it come on when the ac is on? i cannot find out on google.
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Joined: Jul 2005
Posts: 12,316
From: Slightly off center
I'm guessing you used an aftermarket ECTS and not a Genuine GM part.
If you had the ORIGINAL GM part still in there from the factory, it had failed. When it does, it often leaks coolant onto the contacts of the ECTS connector. This leads to corrosion. This particular circuit is extremely sensitive to corrosion, as the voltage drop across the ECTS is being measured, and as the temp goes up, the resistance of the ECTS goes down.
The corrosion adds a bunch of resistance to the circuit. This results in a bogus determination of coolant temp by the PCM, which thinks the coolant is cold and therefore never turns on the fan.
Also, when the ECTS fails, ut usually fails open circuit, which corresponds to an infinite resistance which leads the PCM to think the coolant temp is always -40 -- and therefore the fan is never told to turn on.
1)Check the contacts on the ECTS connector for corrosion. If corroded (usually green), replace (see below)
2)Check the circuit wiring where it meets the contacts of the connector. Broken or damaged wires here will leave the circuit with too much resistance or open circuit (see above).
Your ride is 20 yrs old. Treat it to a new Genuine GM ECTS (all brass design) AND ECTS connector with a wiring pigtail.
Amazon Cost:
----------------
The AutoZone /Advanced/etc sensor is not application specific, and, per one of our members who has worked for both, never buy electrical parts form either store. Their return rate is over 50%. Cheaply made, some DOA.
Please check back with us to let us know your progress.
If you had the ORIGINAL GM part still in there from the factory, it had failed. When it does, it often leaks coolant onto the contacts of the ECTS connector. This leads to corrosion. This particular circuit is extremely sensitive to corrosion, as the voltage drop across the ECTS is being measured, and as the temp goes up, the resistance of the ECTS goes down.
The corrosion adds a bunch of resistance to the circuit. This results in a bogus determination of coolant temp by the PCM, which thinks the coolant is cold and therefore never turns on the fan.
Also, when the ECTS fails, ut usually fails open circuit, which corresponds to an infinite resistance which leads the PCM to think the coolant temp is always -40 -- and therefore the fan is never told to turn on.
1)Check the contacts on the ECTS connector for corrosion. If corroded (usually green), replace (see below)
2)Check the circuit wiring where it meets the contacts of the connector. Broken or damaged wires here will leave the circuit with too much resistance or open circuit (see above).
Your ride is 20 yrs old. Treat it to a new Genuine GM ECTS (all brass design) AND ECTS connector with a wiring pigtail.
Amazon Cost:
Genuine GM 21025106 Engine Coolant Temperature Sensor $12.50
GM 12117087 Engine Coolant Temperature Sensor Connector Amazon: $20
Solder and shrink wrap, do not butt splice.----------------
The AutoZone /Advanced/etc sensor is not application specific, and, per one of our members who has worked for both, never buy electrical parts form either store. Their return rate is over 50%. Cheaply made, some DOA.
Please check back with us to let us know your progress.
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