Hey man I see you do PCM work. I have a '94 Formula A4 that I bought in December. I bought it from a shady car dealer. The cooling fans had not been coming on so being the smart guy the dealer was he tried to wire the fans to the fuse box. That didn't work. I have since just ran the car with the AIR pump fuse pulled so i could actually drive. I am starting to have some extra money now so i'd like to get this fixed.

First, I took the car to a shop, they found the coolant sensor in the water pump was dead. Bingo I thought, got it fixed, Wrong, the fans would still NOT come on. They spent an extra 2 hours searching my electrical system. They think they found the problem. The wiring that the dealer did may have screwed up the PCM. Is that possible? Wiring the fans to the fuse box could mess up the PCM? I want to make sure before I spend some moeny replacing the PCM.

Lastly, What am I looking at to buy/trade a PCM from you? I'm not looking at any tuning at the moment, I just want a working PCM. Damn SES light is annoying. Let me know. Thanks

 

Hi,
sorry to hear about your headaches. Some dealers out there are real a-holes. They will do anything just to sell their car. I know from personal experiences....

Anyway, I doubt the PCM is bad. You probably still have something wrong with the wiring or some other bad sensors.

If you want me to send you a PCM just to try, you could pay the $130 fee I charge for PCMs. I will load the latest GM calibration for your car in it and you could give it a try. If that fixes your problem, then you can just keep it. If not, you can send it back to me and I'll refund the amount, minus $15.

How does that sound?

 

By the way, did you scan the car for codes? Or is the SES from the AIR pump?

 

SES is from the AIR pump. The fans run fine with the fuse pulled. The tech at the shop said the PCM was reading the temps from the coolant sensor, but not turning the fans on. Could the drivers be bad or something?

Should I try disconnecting the battery? I had that sensor put in and all, so...............????

 

Disconnecting the battery won't change anything. I also don't think the drivers are bad because the PCM is the one who detects the malfunction, sets the code, lights up the SES and turns the fans on. (The fans will stay on for as long as there's an SES light present)
So it sounds like the PCM is still driving the fans unless it has a different driver for the SES cases. (which kind of makes sense in a situation like yours)
I guess it may be worth a try to swap the pcms.

 

What I was thinking was that disconnecting the battery would reset the PCM. Which was never done after the sensor replacment.