overheating/radiator fan not kicking on
12-19-2011, 04:46 PM
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overheating/radiator fan not kicking on hello. i have a over heating problem. well the car dosent overheat when its moving but only in heavy traffic or just sitting there at idle, also when the a/c is on it dosent overheat. i started with the fans one dose not kick on and the other kicks on when the ac runs so i unplugged the one that was not running and wired it to the battery and it came on. now i know the fans work next i went to the fuses and relays. the fuses were fine and i swaped out some relays and still the fan wont kick on when i hits the hot range. so now im stuck and i dont know what else it would be. i can drive perfect when the a/c is on. i just want everything to work like it should. if all else fails i can toggle switch it but im not all in to rigging something that's in perfect shape. can someone throw me some advice? HELP ME PLZ!! lol thanks
12-19-2011, 05:17 PM
#2
hello. i have a over heating problem. well the car dosent overheat when its moving but only in heavy traffic or just sitting there at idle, also when the a/c is on it dosent overheat. i started with the fans one dose not kick on and the other kicks on when the ac runs so i unplugged the one that was not running and wired it to the battery and it came on. now i know the fans work next i went to the fuses and relays. the fuses were fine and i swaped out some relays and still the fan wont kick on when i hits the hot range. so now im stuck and i dont know what else it would be. i can drive perfect when the a/c is on. i just want everything to work like it should. if all else fails i can toggle switch it but im not all in to rigging something that's in perfect shape. can someone throw me some advice? HELP ME PLZ!! lol thanks
Well, sounds like you did some good diagnostics. I would say if you checked all relays/fuses and you know the fan is good, then you either have a wiring problem or the PCM is bad. Fans are commanded on by the PCM so I think your next best step is to see if the PCM is commanding the one fan on. You'll need a wiring diagram that shows which pin/wire feeds the fan that isn't working. A Tech 2 or similar scanner would come in really handy so you can just command the fans on and test for power.
12-20-2011, 03:02 PM
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If your ECT is bad (example always reading cold) then your fans will never kick on due to temp because the pcm still reads cold.
As lt1pwr1 said, hook up a scanner which you can see what temp the pcm see at the least and if possible command the fans on and see if the pcm is sending the ground signal to the relay.
As lt1pwr1 said, hook up a scanner which you can see what temp the pcm see at the least and if possible command the fans on and see if the pcm is sending the ground signal to the relay.
12-21-2011, 06:24 PM
#4
At no time on the V8 cars does just one fan come on,, they are wired in series for low speed, and then switch to a paralell setup when High cooling is called for, which is sent by the PCM, The PCM sends a ground signal which is what activates the relays. Here is a schematic,,..Hope this helps..
I used some markers to track power (not the same color as the acutal wires but close), the orange is power to the coils of the relays, the pink is actual batt power for the fans. the blue and green are ground signals from the PCM, and black is just ground.
I used some markers to track power (not the same color as the acutal wires but close), the orange is power to the coils of the relays, the pink is actual batt power for the fans. the blue and green are ground signals from the PCM, and black is just ground.
