I am totally frustrated as soon as I start the car the cooling fan comes on. I have a single fan set up. I replaced the entire wiring harness from the ECM to the sensors under the hood. I switched out my ECM with one that before would not engage the fan and the same problem exists. I have also replaced the coolant fan relay. I can disconnect the green wire that attaches to the coolant switch (passenger side of block) and the fan still runs. I have also tried disconnecting the alt, coolant temp sender, knock sensor but the fan will still engage as soon as I start the car, literally 1 second after car starts the fan comes on. Any help would be most appreciated. The other bad thing is I have no idea when this started. Recent mods were, serpentine set up, and MSD 6AL box, fuel pump, adj FPR. Also this year replaced motor, tranny, and rear diff. Oh it also never had a 383ci like I was told when I purchased it just had a 350ci.

 

It is in the AC default switch. The comp thinks the AC is on and turns the fan on. Look at that circuit.

 

I have looked over all the scematics, and read quite a few stickies and I have no Idea where to look. My car was orrigionally equiped with air but I am now using an A/C delete box (has been in for quite some time before this started happening). There was a light green wire in the same wiring loom by the heater box under the hood which is disconected. I also re-attached all the correct ends to the ones on the drivers side hoping this would help...down to the conecter with the Diode attached to the end.

 

the fan relay is located on the driver side firewall ( looks ovalish ). I had to replace mine a couple of weeks ago due to the same reason. here is a link to the part http://www.partsamerica.com/ProductD...pe=600&PTSet=A

 

I only know of one fan relay which is on the passenger side front right next to the radiator. The ones on the driver side front are for the head light motor. The only other one which looks simular is on the firewall which is the MAF Burn off relay. I have replaced this as well (pass side) and still have the same problem. Any one know which wire goes to the ECM and tells it that the air is on? I will hook up a fan switch to this wire once found. I have a scematic which shows this wire as gray but the other wires on it do not match what is in the car. And the scematic that is in the Chiltons manual (which does match what I have) does not show a wire that would trigger the ECM that the A/C is on. The gray wire is one of the 3 for the TPS. I would rather know for sure which wire it is before I start hacking and end up with another wiring mess. Do I need to just locate the wires from the old wiring loom and see if any of the wires go to the ECM from where they would have attached to the A/C?

 

I have the dual fan setup and i had this problem too. Two days ago my fan went out and my damn car almost overheated. I figured out the fan was bad, replaced the fan and i no longer have the problem.

 

Does anyone know of where to get that connector that sits on top of the A/C comprossor........

Mine burned out there........and it seems its got a resistor in it...I think its a mod.....

I want to replace that plug and see if the fans turn on by them self...and not on all the time

 

Well it sounds like their shorting to ground. If it was before your fan I would think it would blow your fuse. The ground could be coming from the ECM. In which case you have a bad ECM. I mean if its grounding that fan when its not supposed to. Hopefully you can look at the PIN data ona scanner and see what the ECM seems and try and figure out what and why its doing it.

 

My fans start up right when you move the key forward one time before you start it. How can I fix this? I think the person that had the car before me rigged this up.

 

Also fans go on when it's running in limp
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