Hello all,
I'm having a problem getting my cooling fan running in my 1991 Camaro RS 3.1L V6. I checked the relay and it works and even replaced it with a new relay. All of the below was is tested at teh relay. They are the four wires that connect to the relay, and the letters correspond to the Alldata and Chiltons guides.

- The brown trigger wire (D) does have power when the power is turned on.
- The red power wire for the fan (E) also has power.
- The black and red wire that goes to the fan (A) has a good connection to the fan which has a good ground.
- The green and white wire (F) does NOT have a ground. It connects to the ECM which is not grounding out this wire. I even changed the ECM and the chip, but it still doesn't ground out. The car itself runs fine except for a high idle which I'm getting a code 43 at the ECM, I believe the knock sensor is disconnected which should have nothing to do with this.

I'm at a loss here. If any one has any idea as to what might be causing this it would be much appreciated. Otherwise I'll just rigg the relay to turn the fan on with the ignition.

Thanks

Brian

 

First thing to do is to make a small jumper with 2 spade connectors the same size as the relay lugs, remove the relay plug and simply jump the 2 heavy guage wires( red and blk/red wires)on the relay plug. Make jumper out of same guage wire or it will burn your fingers or burn up like a fuse. Does the fan run then? If not the fan motor is bad. If it does run then the relay is not being energized. Next with the relay plugged back in, ground with a clip lead or test wire the grn/wht wire(it won't hurt the ECM)and with the key on see if the fan turns on. If it does then it's something related to ECM or an input to it. RARELY is it anything to do with the ECM. How about A/C, if you turn on the A/C the fan should kick on. Don't forget the fan won't run till over 200 degree coolant temp. Get back when you test these things out-use caution when jumping the power wires for the fan, make sure you are in the right pins on the plug for the power wires, don't jump any other wires than the 2 heavy ones. You can damage the ECM if you hit the control wire(grn/wht) with straight 12 volts.

 

Hi Danno, thanks for the reply. I have jumped the two large wires and the fan does come on. I tested the green and white wire for a ground with the A/C on and it does not show a ground at all. I didn't try to ground it because I was afraid it might burn up the ECM (I have 2 ECMs and tried both), but now that you say it won't I will have to try that next weekend. To test the relay I did put jumper wires from the batterty directly to the grn/wht (-) and the brn (+) leads on the relay and it does click on, so I know the relay is good. At this point I kind of stumped. I did try 2 different ECM's and also 2 stock chips and 1 chip that I burned my self (only changes being raise the speed limiter to 155 and turn off VATS) and it still did nothing. The fan did work before but now for some reason wont. I checked the 3 ground wires on the back right side of the motor and they're fine, I also checked the 2 ground wires on the back left side of the engine and they're fine too. I can't seem to find a bad ground on this car anywhere.

Thanks again,

Brian