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I Need some PCM information!

Old 08-30-2014, 02:56 PM
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Location: Destin, Florida
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Default I Need some PCM information!

Alright guys here is what I have going on. Vehicle - 2002 Camaro Z28 A4.
Problem - The cooling fans will not turn on when the car goes above operating temperature. I have checked source voltage to relays and fuses, found no problems. Self actuated the 3 fan relays, all 3 are working and resistance is within spec. Fuses show source voltage and no signs of excessive amperage. I test drove the car while watching live data of the ECT sensor and saw that the scan tool was able to watch actual values of the ECT operating. For giggles I measured the ECT sensor resistance and got 1.3K-Ohms, tested a known good ECT and received the same resistance. So ECT seems to be doing it's job. I also self actuated the fans with 12V and fans kick on with no signs of them being weak or seized. No DTC's were found. So let me ask this, the PCM is the ground source for the cooling fans right? ECT gets its input from the temperature it reads then relays that information to the PCM and then the PCM actuates the fans? I think the PCM isn't sending the information to the fans to turn on. What do you think? I don't have a way to actuate the fans through the PCM with my scan tool but I do know the ECT is working just fine. If I have to replace the PCM can I buy a reman DELPHI from my local parts store and have GM flash it or how does that work. Thanks.
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Old 08-31-2014, 10:20 PM
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To avoid throwing parts at it, borrow a good scan tool, you need to use bi-directional controls to command the fans on.
If they turn on you have some tuning or sensor problem. If they don't then the problem is wiring or the PCM
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Old 09-01-2014, 07:47 AM
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what ECT were you seeing. factory turn on isnt until 226low/234high
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