Cooling fans are not working at ALL! Lost.
09-06-2014, 01:52 PM
#1
Staging Lane
Thread Starter
Cooling fans are not working at ALL! Lost. 2002 Camaro Z28 - I'm completely lost right now. My car is overheating and my fans are not kicking on at all. When I am driving, the car runs at 197 degrees and doesn't go up until I come to a stop (Thermostat is for sure opening). I checked voltage at both fan fuses (10A and 40A) and I have source voltage coming across both of them telling me the fuses are fine. I actuated the 3 fan relays by putting 12V to them and all 3 of them clicked. I then put 12V to both fan motors, both of them spun right up. After this I swapped a known good PCM out of the same exact car into mine, got my car to go past normal operating temperature, still no fans. So far I have changed out the ECT, PCM, Thermostat and Radiator. (Thermostat and Radiator were changed a month ago because of leaks). Anybody have any ideas??? How do I jump the relays?? Any grounds I should be looking at??? I have my DMM to measure voltage and resistance, just don't know where to look. Thanks guys.
09-06-2014, 05:28 PM
#2
The "click" you hear in the relay is it connecting the power in/out leads to the fan(s). You could jump those together by taking the relay apart and soldering the two points together or even using a shim of sorts. The top of most relays is very easy to pop off and it becomes real obvious how it works once you can see it. Also the underside of most relays has the wiring and activation schematic right on it.
Or you could buy a $2 pack of male blade connectors and some ~#10 wire and make a short jumper. Probably easiest and quickest. This would make the fans run all the time.
That being said, put a voltage meter on the wire that should activate the relay from the PCM to the relay. Warm the car up. Once it reaches the temp where the fan should come on, see if you have 12-ish volts there. If yes, the computer signal is likely getting there. If not, trace back to the computer. I don't know which one, but a fan activation wire should directly correspond to a specific pin from the ECU. Make sure there is no corrosion on that pin on the PCM or harness and that you are getting a tight fit. Some dielectric grease on all of the above could be helpful but all electrical connectors in the circuits should be nice and clean.
You are making a mistake by assuming that a relay is working because it clicks. I have made that mistake plenty of times also. Often the solenoid in there continues to work after the electrical contacts have gone bad from arcing or similar. Relays definitely wear out and do not last forever..and don't always fail the same way.
Good luck!
Or you could buy a $2 pack of male blade connectors and some ~#10 wire and make a short jumper. Probably easiest and quickest. This would make the fans run all the time.
That being said, put a voltage meter on the wire that should activate the relay from the PCM to the relay. Warm the car up. Once it reaches the temp where the fan should come on, see if you have 12-ish volts there. If yes, the computer signal is likely getting there. If not, trace back to the computer. I don't know which one, but a fan activation wire should directly correspond to a specific pin from the ECU. Make sure there is no corrosion on that pin on the PCM or harness and that you are getting a tight fit. Some dielectric grease on all of the above could be helpful but all electrical connectors in the circuits should be nice and clean.
You are making a mistake by assuming that a relay is working because it clicks. I have made that mistake plenty of times also. Often the solenoid in there continues to work after the electrical contacts have gone bad from arcing or similar. Relays definitely wear out and do not last forever..and don't always fail the same way.
Good luck!