I'm trying to add '05 Truck E-Fans to my '98 swap truck and I'm having problems getting only one fan to turn on. I'm using a PCM with a 411 service code, should be a 2001-2002 PCM. I also got my hands on a factory GM fan harness from an '05 truck. So I pinned the fans just like they would be on a factory truck from GM, dark green to pin 42 on the blue pcm connector, and dark blue to pin 33 on the red pcm connector.

I then used HP Tuners to flash the PCM just like an '05 truck, fan 1 to come on at 226* and off at 219* and fan 2 to come on/off at 235*/227*

Anytime fan 1 comes on, both fans turn on. Even using the PCM controls in VCM Scanner, they only respond to on/off for fan 1. The fan 2 controls do nothing. I've tried playing with the temperature controls in the PCM to only get one fan to come on also, and they only respond to the fan 1 temp controls. Fan 2 controls have no effect on the fans at all.

Anyone have any ideas, or am I just stuck having both fans come on?

 

The PCM's changed sometime after 02 to have two separate fan pins. On the older style PCM's like you have (and the rest of us 99-02 guys), the only pin that operates the fans is blue 42. Most guys who add e-fans to the older trucks use pin 42 to allow the fans to come on at low speed and then the a/c clutch wire to trigger the fans to come on high speed.

 

Using HPTuners are you able to specify the type of fans you have attached? aka, Auxiliary vs Series Parallel?

Since that 0411 PCM was used for fbodys and vettes, and they had e-fans controlled by two pins, it would stand to reason that you should be able to just fine as well.

 

that should be a choice, it is in every tune for HP Tuners I've looked at.

 

I have the choice between auxiliary, disabled, or two fans.

From what I understand both fans come on at low, then on high, should they run at a higher speed. From what I can tell, they are only running at one speed and the high speed in the PCM has no effect on the fans.

 

I could be wrong, but I think moregrip looked into this awhile back and came to the conclusion that the only PCM's that could control fans with two separate pins were the newer ones. If it is possible with the older ones I'd like to know how to do it.

 

The older PCMs definitely can, my trans am does.

Just make sure you have it set up for "Two Fans" as Tim specified that is an option. To be sure, open up a stock trans am or z28 camaro and use the same settings they have.

Justin