Have this 2004 Colorado 4x4 build with a 5.3 gen3 using E40 Trailblazer and t42 Tcm. Truck is running and to finalize this build I'm looking into running electric fans. From a group on Facebook a popular fan of choice is out of 08 or so Charger as the dimensions are perfect for the radiator. Problem is the blazer has clutch fan with a Hall sensor. I made this harness custom and do not have any of that. Was planning to using relays and C1- Pin 36 as the control. In the schematic that wire goes into a relay then powers the motor. Just unsure about how that wire energizes to turn the fan on, what the settings should be set to, if the Hall sensor portion is needed OR worst case scenario special fan control module needed. Appreciate any input!
Copy the low speed side of a '05-'06 GTO. Those used regular relay fans.
The control pin(s) in the ECM provide a ground when activated, so you'd have constant power to one side of the relay coil and the ECM completing the ckt to ground when fan is requested.
I have what are the heavy duty dual fans from 08-09 charger. Are controlled by Pcm, variable speeds, and relays are used. Unsure if brushed or brushless were pulled from junkyard. So with my pin out situation C1-36 is cooling fan clutch control C1-23 is Speed signal. C3-33 is Low Reference an 35 is 5 volt Ref. This is a different setup from my 1990 c1500 2005 6.0 swap Blue and Green connecter Pcm.
If they are variable speed fans there will have to be some kind of controller, either between ECM and fans or built into the fan motors. The ECM can't do variable speed to a brushed fan without some other module inbetween to handle the high current switching. If they're brushless the controller will be built in and it'll use 3 wires, constant B+, constant ground, and a PWM signal.
After looking at a few diagrams there are 3 relays used, one high speed signal and on low kind of like the green and blue connecter on a gen3 pcm besides the 12 key hot, this look constant B+.
For a 2-speed brushed motor fan you need two relays and two ECM output pins. Low speed feeds the fan terminal with the resistor, high speed feeds the one without.
You would use only two relays - C1 36 to ground the relay that powers the resistor/low speed pin at the fan, and C1 56 to the relay that goes to the non-resistor/high speed fan pin.
If you change the settings from the Trailblazer's PWM EV/1 fan*/2Hz to Discrete/2 fans/128Hz, and the relevant stuff in State vs Desired & Output vs State...
* 'Number of fans: 0/1/2/3' actually means the number of fan output pins being used, not the number of motors with fan blades on them. A single two-speed fan needs two output pins, so Number of fans: 2.
Just so you and anyone else that sees this later is clear, the Charger fan-thing is not variable speed, it's multiple speed, which is completely different animals.
Sounds good, Thank you for your help and patience I really appreciate it. I didn't have this much confusion with my first LS based swap lol. So i will pin into c1-36 c1-56, use the Similar wiring schematic as the GTO with two relays to be fully comprehend.
What I gather from that page is that:
Std cooling = dual fans, two 2-pin connectors
HD cooling = big single fan, one 3-pin connector, resistor integrated into backside of connector
If you have the big single, use the diagram I spent about 40 minutes making.
If you have the dual fans, shit, just use a 3-relay system copied direct wire-for-wire from the unaltered GTO diagram. That way you can have low speed with the fans connected in series and then high speed with both connected in parallel.
Everything works as it should after the long pause. Drove the truck tonight and stayed right in the middle around 203-208 degrees. Thank You for your time and patience with me I really appreciate it.
I'm having a similar situation with a e40. I want to do a ECM single wire to activate 2 fans with relays around 190f. Can you please share your tune to see how should I configure it on mine?
With only a single wire from the ECM, you'll only be able to get all fans on at 100% or all fans off, no matter how many relays or fans you have. Is that what you're wanting?
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