Need to find AUX engine fan pin location.

[Wilde Racing]

I need to know the pins the ECM uses to control the fans on a 2002 ECM (12200411) I think one is 42 but what is the other?

Thank you for any help..........

[Wilde Racing]

With some more searching I have found out pin 33 is the one the LS1 fans use, but mine pin 33 is already being used by the HVAC, What pin does the ecm ground when I command fans high on?

[RoninsDenali]

Pin 33 on the other connector shows "not in use" on my schematics. Perhaps thats the one?

If it is, i'd jump for joy as i'm thinking of building a fan harness that the PCM can control both high and low.

[Wilde Racing]

Nope tried that on mine it is used Recirculation door motor.... but I still might use it...........

[RoninsDenali]

I've done some thinking on the subject. And i'm thinking its a 99-02 issue, as on my 03, all the HVAC wiring is handled by the BCM which happens to be the same year the clusters and BCM's we're updated.

I'd hate to say it but i'm thinking the 99-02 truck PCM's are wired differently than the F-Body's and the 03-05 truck pcms. But i cant verify that as i only have the wiring schematics for my 03 available.

[EC_Tune]

The 03 to 06 trucks are definitely wired different (Green & Red connector instead of Blue & Red) than 02 and earlier. I'm pretty sure the 02 truck PCM is the same as the Camaro. Just need 02 truck wiring harness info and 02 Camaro wiring harness info. The 05 trucks had Efans so compare wiring from 03-04 to 05-06. May find the elusive pin.

04 Vette uses the same OS (same PCM?) as the 04 truck (well, the Vette updated the OS later, but they started out with the same OS)

EC

[FlaBouy]

I've done some thinking on the subject. And i'm thinking its a 99-02 issue, as on my 03, all the HVAC wiring is handled by the BCM which happens to be the same year the clusters and BCM's we're updated.

I'd hate to say it but i'm thinking the 99-02 truck PCM's are wired differently than the F-Body's and the 03-05 truck pcms. But i cant verify that as i only have the wiring schematics for my 03 available.

Slight differences but close... I have actually been designing a wire harness for one of our Avalanche Truck Club member's to use on his e-fans. Pin 42 is the trigger for both fans on low (in series) and Pin 33 is being used as a fan high trigger for either one fan or two fans, depending on the applications. Word of caution: There are fan kits out there that are burning up relays, especially in the nelson harness... The larger 34" dual fans draw 57A on startup. I am using the smaller LS1 fans and have had no issues such as this with my Nelson Harness....We also use the green wire from the A/C compressor on to trigger both fans on low, regardless of the ECT. There are options to install and overide switch for both fans on low and fans on high for the strip......Also, on an 05 PCM the pin 33 is used for high fans in the opposite connector than pin 42......