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I installed the electric fan in my 02 Suburban 2500 with an 8.1 about 4 months ago. I used the harnesses from BP Automotive (for the fans and A/C) and all was working great.... until today. I went to fire up my truck and the fans turn on about 10s after I fired it up. The truck was cold (30 degrees) so it shouldn't be calling for the fans to be on.
Any help diagnosing would be appreciated!Attachment 87118
Mine did this last weekend, my fans would not shut off, I turned my runtime with ignition off to 0 I had it at 30 seconds and I haven't had any problems since. At 30* they shouldn't come on, I unplugged my temp sensor and re seated it as well all is good now.
My issue is with the fans running all the time with the engine running (no matter the ECT). The fans shut off when I turn the ignition off.Quote:
Originally Posted by DougO
It depends how your fans are cycled by the AC. If you are running the defrost and the defrost is asking for the AC compressor...
Quote:
Originally Posted by IARLLC
Your right, I just went out to check and the fans stay on weather I have it set to defrost or not. I gave it some time after turn it off of defrost and they stayed on, ECT was at 30 to 100 during the test.
Is there a way to see in the scanner what is commanding the fans on?
Scan for AC pressure, ECT temp. Some DTC if set will run the fans as well.
I may have it figured out but I will need some help. What is the normal AC pressure sensor voltage when static?
Have you searched the tune repository for a stock 8.1 tune and get your numbers from that?
Attachment 87189 see if my fan settings are close to yours
I think what is happening is that the AC switch (the pressure switch) is sending a high pressure signal to the ECM. When I scanned the the truck ad add the AC pressure voltage to the data stream it was 0.01v and the fans where not on. I was looking at the ECT and then fans kicked on so I checked the AC pressure switch voltage and it had jumped to 4.8v. That why I was asking what the nominal voltage for the pressure switch.
You using a pressure switch or pressure sensor? Here is how to use a sensor on the 99-02s
https://www.performancetrucks.net/fo...ontrol-553385/
Good info 2xLS1, May have a switch and it needs to be a sensor.
I had been looking for a while on what the difference was between analog, serial, and the cycling. Thank you!Quote:
Originally Posted by 2xLS1