My cooling fan issue. (Solved)

[3_97_Sports]

Just giving my experience so it can help somebody in the future.
When I got my white car, it was winter, and I drove it home on the highway with no overheating. When I drove it in town, it overheated within 10 minutes.
The rad fan was not working. I replaced it with one I had here, and it worked again. I drove for a few months, and the used fan I installed quit working.
I got a fan motor from rockauto, installed it, and it worked again.
Now that I had driven the car for a while since I got it, I had figured out that the fan was running all the time the engine was, if you started the car, the fan would not shut off until you shut the engine off.
The fan would run on high until it burnt itself out from not having time to cool itself down.
I tried a different CCRM, no change in the constant fan.
I tried a different coolant temperature sensor, no change in the constant fan.
I tried a different pcm that I had sitting here, it solved my problem, my fan operated as it should.
As an added bonus, the pcm has an old Lonnie tune for a stock 97 on it, so my shift points have improved.
Hope this helps somebody out.

 

[White Lincoln]

Thanks for sharing 3 97. Always appreciate a good rundown of solving a problem.

 

[Kenz]

Glad you figured it out! The PCM going bad can cause many strange issues. When mine went bad the car started rev hanging bad, then after turning it off in a parking lot, it wouldn't start back up. That happened without warning, left me stranded and needed a tow.
It's common for them to have issues with the O2 sensor heater circuit as well. That will turn on the engine light, and in emission inspection states I suspect many people never figure out the PCM is bad and the car ends up getting scrapped.

 

[Rodeo Joe]

I had a problem that started last year, throwing a cam sensor code. Turned out to be the PCM.

Joe

 

[97teebs]

On many cars a sign of failing/failed pcm is when you turn it to the on position but not engine running the fan comes on. Common it several makes of vehicles. Make sure your fresh air vent under the passenger side wiper cowl is in good shape they can leak water directly to the pcm.