I made a post a few months ago about how my cooling fans stopped coming on. I had a bunch of burned wires so i've had a SES light so that was turning my fans on and i didnt have to worry about it overheating. I've seem to got all the rewiring done so now i'm back to not having cooling fans. My madz28 tune has the cooling fans set at the stock operating tempature which is 226 i believe. I have gone past this and the cooling fans never came on and the coolant was boiling out of the coolant resivor.

This is what I know

If I have a SES light the fans work
If i jump pins on the DLC the fans will come on
I've tested all the relays in place of the fog lights they are fine
Ive replaced my engine coolant sensor
I'm not throwing any codes
If i jump the pins in the relay slot the fans will come on

So if anyone can help me out from here i'd appreciate it.

Thanks

 

you have no ground. any time the system works from the power source to the component itself, there's obviously nothing wrong with the wiring or the component. I've never experienced this with a fan circuit, but a lot with other things. if you can jump the relay and it works, then its either a relay or a ground. since your relay is good, its definately a ground. it could physically be a lack of ground, or it could be that something else on the same circuit is open. EXAMPLE: a neutral safety switch on an automatic transmission keeps the car from starting in any gear but neutral or park. It does this by cutting ground to the starting circuit when it senses the selector in gear. it will make the whole circuit dead and make you think something is wrong with the related component. you always have to trace it back to related components.
i looked at the wiring diagram in the haynes manual and it sucks, but it looks like its on the same circuit as the trans lockout solenoid circuit (could be wrong but it looks that way), and in a round about way it reaches back to the ECT sensor. Let me find a better manual tomorrow for the full schematic of the fan circuit.
oh, and any time the pcm cannot read the proper input from the ECT sensor, it will put itself into fail safe mode and turn on the fans automatically. so that explains why they come on when you have the SES light on. you can test that by simply unplugging the ect sensor and watch for the fans to turn on.

 

Anyone got any ideas?

 

Ok also the fans don't work when i turn on my ac.

I used a test lead on plug c100 and tested both the green and blue wires and both worked so this should verify that all my wiring from that point to the fans is good and that all the relays are also. So what else could it be?

 

Use a scanner or data logger to see what commands the PCM is giving the fans. That's the only way you are going to know if they are "supposed" to be on or not. This is mentioned in my article about the cooling system and testing on my Tech Page.

 

Yea I wish I could scan it but I dont have a scanner nor do I have a cable that I could use freescan or somthing with.

 

Check the fuse and if the fuse is blown, replace it then look at the airpump, its on the same curcuit. The airpump could be seized, thats what happened to me, just giving you something else to check, good luck.

Colin

 

Well a few months ago the fuse blew a few times but it finally just stopped. But the fuse is fine now and i just put a new one in just in case. Would a bad airpump cause the fans not to come on? And also wouldnt i throw a code if the pump was bad? I'll look into it though.