greenvortec97

iTrader: (1)

Anyone ever done this before? I know in VCM Scanner my PCM's OS shows a Fan 3 option.. I'm guessing you can enable this and use one of the PCM's pinouts to control it? instead of running the fan off a manual switch..

What I'm trying to do is turn off or turn on the fan via MPH OR Temp. purely for in town driving purposes only. On the freeway the fan would shut off automatically based on speed or temp drop.

I would use a temperature based probe and relay but the fins on my B&M trans cooler do not allow for that.

Pacer Racer

iTrader: (6)

There is no 3rd fan output on a 411 pcm and in the fan selection in the OS there is only 3 choices, no fan, 1 fan and 2 fans

greenvortec97

iTrader: (1)

any idea if it would be alright to pull 12 from the low fan? so the tranny fan comes on when the low fan comes on?

Blown06

iTrader: (32)

You could use the low fan to trigger two relays...

Pacer Racer

iTrader: (6)

That should work, but if you're driving the relay directly with the pcm output, remember the pcm supplies the ground side of the circuit, not the power side

salemetro

iTrader: (5)

Correct.....but he could also use the fan relay's 12v+ output to additionally act as the trans cooler relay's 12v+ "switched" power feed to energize the cooler relay's coil. There are a few ways to do it....but by not "tying in" to the PCM's floating-ground output, there will be less chance of over-burdening the PCM itself, and having an unhappy result.