E-Fans not working correctly

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Nov 18, 2012 | 10:04 PM

AJII

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From: Jackson, TN

E-Fans not working correctly

Need a little help getting my efans to work correctly.

2001 Silverado
2005 Factory Efans and Harness
Using Pins 42 and 33

The problem is that the fans constantly run on Low no matter the engine temp or what I have commanded in the tune (using HPT).

High speed works correctly, and comes on at their commanded temperature.

Everything is wired correctly because I can control the fans using the controls in the scanner. (Low, High, Off).

So, it must be something in the tune. But I don't know what. Everything is set the same as a factory 2005 except for AC Fan Temp, which is lowered to make the fans on whenever AC is on...but right now this makes no difference because the fans are on anyway.

These are the settings I am using. Thanks for any help you can give!

Nov 19, 2012 | 01:09 AM

Ferocity02

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Don't know the answer, but I have a question. Will wiring both wires into the PCM let the PCM turn on the fan(s) when the AC is on?

Nov 19, 2012 | 02:19 AM

AJII

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From: Jackson, TN

It should, but I cant tell because mine are always on AC on or not.

Nov 19, 2012 | 03:40 AM

Funkster

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From: Urbandale, Iowa

I am not tuning proficient in anyway and more than anything I am just curious, is the "Fan 1 On Temp AC On" table set to measure at degrees Kelvin?

Nov 19, 2012 | 05:28 PM

1FastBrick

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From: JunkYard

Did you read this write up???

https://www.performancetrucks.net/fo...-chevy-484892/

He used the OEM 05-up harness on a 99-02 truck. Your answer is in there. You don't use pin 33 with the OEM harness on the 99-02 trucks.

Quote:

The other trigger wire has to be connected to the AC compressor clutch relay wire. That wire is positive, so by me using an OEM harness, I had to add a relay to that wire to change it to a negative in order to trigger the fan relay pack, which is set up to be triggered by negative signals from the PCM.

HTH

Nov 19, 2012 | 05:33 PM

AJII

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From: Jackson, TN

Thats for fan 2 control. Fan 2 works perfectly using the PCM. My scenario seems unique to all I've read online, unfortunately.

Nov 19, 2012 | 06:39 PM

TXSZ66AVLANCHE

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You cant use both pins on a 99-02 truck unless you rewire your harness, 03+ PCM supplies ground to both pins, on a 99-02 the pcm grounds one pin and the other pin is 12v when activated.

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Nov 19, 2012 | 06:48 PM

AJII

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From: Jackson, TN

Using HPT you can change pin 33 to supply ground.

My problem i with the Green wire, pin 42, the empty one every one uses for all installs.

Nov 20, 2012 | 12:21 PM

BigKID

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Your problem is not unique. Lots of guys, including myself, have this issue with early (99-01) truck os applications. I also replied to your post on HPTuners forum.

https://www.performancetrucks.net/fo...-c-not-465926/
https://www.performancetrucks.net/fo...l-time-476546/