I want to use the aux output on my LT8 to turn on my perma-cool e-fan at a set temperature. I have the fan mounted to the radiator and I've already run some wires. I'm not sure if I should to use a standard automotive relay or not and how to hook it up. I thought it would be a better idea, so I started and my brain wuit working on me and I forgot how to hook up the relay. I have the aux output wire from the ECU to the 86 pin on the relay, fused switched 12V to pin 87, and the load wire to the fan on pin 30. The fan is grounded to the body.

Now, is this hooked up right so far, if so, what do I do with the other pin, # 85, on the relay? I can't remember if I'm supposed to ground it or what??


My brain had a major hiccup and I'm confused...

 

you can't run an efan directly from the Microtech aux out wire. the efan pulls way too much current for the driver to support it, it will burn the circuit on the board and possibly cause damage to the other circuits as well.

the aux out is meant to drive switches like those found in relays.

you are going to hook up the relay with the aux out exactly like you hooked up your fuel pump relay.

 

I tried to hook it up like the fuel pump relay, but that relay has two wires to it from the ECU, green and pink.

The aux output is only one wire, I knwo there's a simple way to run this, but I can't remember how...

 

OK, Ray helped me figure it out. Pin #30 goes to the e-fan's ground, #85 gets fused 12V, #86 gets the white aux output wire from the ECU, and #87 gets grounded. The power of the e-fan goes to a 12V fused source.

 

*UPDATE*

It works. I set the turn on temp to 90 C. Thanks again Ray.

 

Lets see if I remember right.

86= switched +12 volts
87=constant +12 volts ( fused from bat.)
30=load (fan)
85= ground

I think that's right.

 

I just checked the relay for my e- fan. I have it wired the same way that I posted. It's always worked. who knows..........maybe we can wire them more then one way and they will work.

 

there are a ton of different ways you can use relays... i just happened to tell jim my way of doing it. I use the Fuse on the positive side of the efan and use the relay on the grounding side of the efan. the relay is just interupting the signal to ground.

remember, a relay is just a switched high amperage switch :-)

 

OK, I've got everything set-up right and the fan comes on at 94C and shuts down at 89C. I've noticed that the idle drops from 820 to 750 with the load from the fan, and down to 680 with other accessories on in my car, wipers, lights, and heater fan.

I guess I miss my BAC a little now..

 

Which is why I have the PWM output added to my LTX-8

 

I'm lucky my Flex-A-Lite Black Magic #150 has It's own thermostat/function. I don't know you my LT8 will respond without a BAC Valve though.

 

The ASV (little solenoid on the back of the UIM) works great as a binary idle control solenoid. Hook it up into your fan circuit and it'll add about 200 RPM whenever the fan kicks on. It's good stuff.

Brandon
BR7 Racing

 

Dammit. I guess gotta find one of those little bastards now, mine is in a landfill somewhere...