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BAD PCM?


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REYGS
User

Nov 21, 2006, 5:11 PM

Post #1 of 3 (2773 views)
BAD PCM? Sign In

1998 cavalier inop cooling fan. new fan motor and relay there is power at relay but no ground from pcm. BAD PCM? HELP!
Forgot to mention new temp sensor also.


(This post was edited by REYGS on Nov 21, 2006, 5:18 PM)


steve01832
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Nov 21, 2006, 5:57 PM

Post #2 of 3 (2768 views)
Re: BAD PCM? Sign In

The computer monitors the engine temp via the coolant sensor. When it sees a predetermined value, it completes the ground side of the fan relay coil. You should first check for voltage at two of the relay connectors with the key on. Then you should take the test light from battery positive and touch the remaining two terminals. At one the light should glow. This is ground. Start the car and test the remaining terminal with the test light connected to battery positive. You can even turn the A/C on. If the test light glows the PCM is fine. If the computer does not turn the light on when the engine temp guage gets to almost hot, you need to check the coolant temp sensor and the wire between the PCM and the fan relay for an open condition. An ohmmeter is the best way to do this. Let us know what you find. If I can remember I'll try to get you a PCM pinout chart for your car tomorrow.

Steve


(This post was edited by steve01832 on Nov 21, 2006, 6:01 PM)


REYGS
User

Nov 22, 2006, 1:47 PM

Post #3 of 3 (2761 views)
Re: BAD PCM? Sign In

Thaks for the advice. I will do. And yes the fan comes on with AC on. I will get back with you.






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