Using ECM to control Elect Fans

Rockrz · Post by **Rockrz** » Sat Jun 13, 2009 7:37 pm

When I had my electric fans on my '96 truck, I used the Flex-A-Lite
control module.

On my new truck, I want to wire my fans up to the ECM now that
I have HP Tuners where I can control each fan.

So, my questions are:

1) What slot ECM do I wire Fan #1 to, and what slot
do I wire fan #2 to? (I have dual SPAL 12in fans)

2) When you wire to the ECM, is that just a signal wire
to activate the fans and I would still need to provide
a power supply for the fans that is independant of
the ECM plug in?

3) How do you get the ECM to turn the fans on when
I'm running my A/C.

This should all be doable since many GM vehicles
come from the factory with electric fans and they
are controlled by the ECM

F9K9 · Post by **F9K9** » Sat Jun 13, 2009 7:43 pm

You didn't even leave a foot print on my head. Way over my head to even tell you where to look, Sorry.

Rockrz · Post by **Rockrz** » Sat Jun 13, 2009 7:55 pm

Well, I have a picture that shows all of the slots
where the wiring goes into the ECM and each
slot is numbered.

I just gotta figure out a few more details
on it to get this all rigged up factory style

roadrunner · Post by **roadrunner** » Sat Jun 13, 2009 8:39 pm

Brule will need to chime in here but I would think that due to electrical loading that you would only be able to use ANY wires from the ECM as trigger wires. This would mean they would only turn on a relay that would carry the actual electrical load of fans wired to the battery through the relay or anything else you should choose to wire in. As far as the AC turn on that might have to be wired to the AC system as a trigger. Unless there is a control wire for that from the ECM as well the drawback would be fans running on defrost as well. If the PCM is capable of fan control signal it may also turn on the fans when the controls at the dash are in AC mode. I would be the first to admit I don't know for sure on the trigger capability of the PCM or if it makes a difference as to the year of the truck.
Bear in mind the PCM is not generally set up to handle high load accessories and is generally used as a trigger and sensor only.

Rockrz · Post by **Rockrz** » Sat Jun 13, 2009 9:23 pm

Yep, I figured it might only serve as a signal
and not as the power source.

If it's going to be too complicated, I could always
use the Flex-A-Lite control module which is pretty
easy to setup and seems to be reliable.

raven2510 · Post by **raven2510** » Sun Jun 14, 2009 3:23 pm

i have the threads saved on my other computer for what you need. i will get it when i get on later tonight.

Rockrz · Post by **Rockrz** » Sun Jun 14, 2009 4:57 pm

Kewel...thanx!

Rockrz · Post by **Rockrz** » Fri Sep 25, 2009 7:54 pm

raven2510 wrote:i have the threads saved on my other computer for what you need. i will get it when i get on later tonight.

Ever find them instructions?

raven2510 · Post by **raven2510** » Thu Oct 29, 2009 10:00 am

sorry it took so long
http://www.s10planet.com/forum/showthre ... ectric+fan

Rockrz · Post by **Rockrz** » Thu Oct 29, 2009 11:17 am

k00L, thanks!