Overheating Issue
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1st Gear Member
Joined: Mar 2007
Posts: 168
From: McCaysville, GA
Overheating Issue
I am sure this issue has been addressed before, but after 45 mins of searching on the forums, I didn't find anything. Here is my problem, I have a 94' Z28, the fans are not coming on unless the A/C is on. I have changed out the sensor in the water pump. What else could be the problem?
April 2011 ROTM
Joined: Mar 2009
Posts: 22,015
From: Tokeland, Washington
ROTM Winner's Club
check this thread out it has some good stuff in it.
https://camaroforums.com/forum/lt1-lt4-tech-9/cold-anti-freeze-hot-motor-39140/
https://camaroforums.com/forum/lt1-lt4-tech-9/cold-anti-freeze-hot-motor-39140/
In the Staging Lanes
Joined: Mar 2009
Posts: 85
From: Colorado
There are three fan relays that connect in the fuse/relay panel. If I remember correctly, you can activate the fans in low speed by jumping the connectors in the fuse/ray panel that one of the fan relays plugs into. You can turn the fans on high speed by jumping the connectors where a different fan relay connects (If I could take a picture right now I would). You leave the last fan relay alone.
Test the high and low fan speeds by jumping the connectors in the fuse/relay box panel. If the fans turn on, do what Domestic Disturbance said and swap out all three relays and check the fan fuse. If the fans don’t turn on, there’s an electrical problem in the circuit and you should check the blue and green wires coming out of the ECM/PCM (http://shbox.com/1/fan_sw_diagram1.jpg) and the voltage in the fuse relay panel (see repair manual). The fans in my car wouldn’t turn on either and everything tested out fine. I eventually fixed the problem after I bought C.A.T.S. tuning software and reprogrammed my PCM to turn the fans on when I wanted.
Potential problems:
- 3 fan relays
- 1 fan fuse
- Temp gauge sender is inaccurate (gauge is wrong - car isn’t hot enough for fans to turn on)
- Coolant temp sensor – YOU ALREADY REPLACED THIS
- Voltage at coolant temp sensor – Should be close to 5 volts (same as IAT sensor)
- Circuit between PCM/ECM and fuse relay panel (check wiring and fuse relay panel)
- Circuit between fuse relay panel and the fans (check wiring)
- PCM/ECM needs to be reprogrammed (the problem with my car)
Additional help:
http://shbox.com/1/4th_gen_tech2.html#cooling
Test the high and low fan speeds by jumping the connectors in the fuse/relay box panel. If the fans turn on, do what Domestic Disturbance said and swap out all three relays and check the fan fuse. If the fans don’t turn on, there’s an electrical problem in the circuit and you should check the blue and green wires coming out of the ECM/PCM (http://shbox.com/1/fan_sw_diagram1.jpg) and the voltage in the fuse relay panel (see repair manual). The fans in my car wouldn’t turn on either and everything tested out fine. I eventually fixed the problem after I bought C.A.T.S. tuning software and reprogrammed my PCM to turn the fans on when I wanted.
Potential problems:
- 3 fan relays
- 1 fan fuse
- Temp gauge sender is inaccurate (gauge is wrong - car isn’t hot enough for fans to turn on)
- Coolant temp sensor – YOU ALREADY REPLACED THIS
- Voltage at coolant temp sensor – Should be close to 5 volts (same as IAT sensor)
- Circuit between PCM/ECM and fuse relay panel (check wiring and fuse relay panel)
- Circuit between fuse relay panel and the fans (check wiring)
- PCM/ECM needs to be reprogrammed (the problem with my car)
Additional help:
http://shbox.com/1/4th_gen_tech2.html#cooling
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