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Thread: 2001 Chevy Tahoe E-Fan Conversion.

  1. #1
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    2001 Chevy Tahoe E-Fan Conversion.

    Hello Everyone, I have been wanting to do the dual electric fan conversion for a while and Finally got around to it.

    I was at a Salvage yard and found the fans and wiring harness with the relays from a 2005ish truck, didn't really look at what the year was.

    So I Pinned the green trigger wire to pin 42 on the blue ecm connector, the blue wire was tapped in to the existing wire on pin 33 on the red ecm connector.

    The relay box fits inside of the fuse box to the right side between the box and the firewall, you have to remove the fender support, remove the top fuse box cover, and then remove the outer box from around the fuse block, there is a space where the fans relay box fits inside there, It is made for it, but a pain in the ass if you have to access it to replace a fuse or relay.

    Basically I cut the harness off of the truck I removed it from, the harness includes extra wires that won't be needed, so I took them out.

    I installed the fans, mocked everything up, cut the wires to length how I wanted them, I attached the red 12V feed to the left side of the fuse block, I grounded both the fan ground and the relay ground to the side of the alternator bracket.

    Then I loomed everything back up and zip tied it so it won't move.

    So then, I connected through the VCM SCANNER, I used the vehicle controls and special functions button, went to system, and tested the fan operation to make sure they turned on and off and sure enough they do.

    Now, I have tuned it to where I think the fans should kick on and off, But I would like some advice on where it SHOULD be set to turn on and off.. What temperatures to enable fan #1 and Temps for Fan #2.. What speed should they disable?

    I have Fan #1 set to enable at 190 degrees and disable at 185 degrees, fan #2 to enable at 220 degrees and disable at 210 degrees.

    Fan #1 to disable at 25 mph

    the rest is basically set to 0.

    I have attached the tune.

    Any suggestions are much appreciated, It seems to be working fine. I just want to make sure it is set correctly. Thanks2000 model fan diagram.jpg
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    Last edited by Chris Barker; 06-04-2020 at 10:35 PM. Reason: add wiring diagram
    2017 F250 6.2 XL

  2. #2
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    The factory thermostat doesn't fully open until approximately 196 degrees. You should set Fan 1 to just above this temp. I typically set fan 1 to 205/200 and fan 2 to 210/205.

  3. #3
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    If you will log your ECT, I have found it stays at 205 with fans on at 195 off at 188*. I also found with both OFF in hot blacktop parking lot, ECT would stay about 210-215 with ambient at 93*. If setting your fans at 195 makes you happy do it.

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    **UPDATE**

    So for MY tahoe, I had wired the trigger wires as shown in the diagram in my first post, green wire to pin # 43 on blue ecm connector, blue wire tapped to pin # 33 on red ecm connector, I do not recommend tapping # 33 on the red connector as it puts out a 12V + signal, the fans use a Ground Signal.

    I ended up disconnecting my blue trigger wire, tapping into the a/c compressor engage wire and using a relay wired with negative polarity to trigger the #2 ( Blue ) Trigger Wire to kick fans on high when the a/c is engaged..

    I was having some issues with the fans staying on after the key was turned off, and finally had gotten that issue fixed, but today, my RECIRCULATION actuator started click non-stop.. That is the reason I started looking at the wiring again.. I don't know if having it hooked up to the #33 pin caused the actuator to start acting up, or if its just old and started giving out finally, I mean my tahoe does have 230,000 miles on it now.. But now I have to remove the top piece of the dash to get to the actuator, for now, as long as I leave the recirculation button engaged, it stops clicking. So it will have to just stay that way for a little while until I get the time to change it out.
    2017 F250 6.2 XL

  5. #5
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    When you a/c compressor cycles, does it cause you fan to cycle on and off also? That's what happened to mine when I tapped into the a/c compressor wire.. So I hooked mine up the way you did the first time with red plug pin#33 and its been working flawlessly..
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  6. #6
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    Quote Originally Posted by Chris Barker View Post
    **UPDATE**

    So for MY tahoe, I had wired the trigger wires as shown in the diagram in my first post, green wire to pin # 43 on blue ecm connector, blue wire tapped to pin # 33 on red ecm connector, I do not recommend tapping # 33 on the red connector as it puts out a 12V + signal, the fans use a Ground Signal.

    I ended up disconnecting my blue trigger wire, tapping into the a/c compressor engage wire and using a relay wired with negative polarity to trigger the #2 ( Blue ) Trigger Wire to kick fans on high when the a/c is engaged..

    I was having some issues with the fans staying on after the key was turned off, and finally had gotten that issue fixed, but today, my RECIRCULATION actuator started click non-stop.. That is the reason I started looking at the wiring again.. I don't know if having it hooked up to the #33 pin caused the actuator to start acting up, or if its just old and started giving out finally, I mean my tahoe does have 230,000 miles on it now.. But now I have to remove the top piece of the dash to get to the actuator, for now, as long as I leave the recirculation button engaged, it stops clicking. So it will have to just stay that way for a little while until I get the time to change it out.

    Is this the fan functions you had Chris B? I was looking at the relay wiring. 2 are 4pins and 1 is 5pins. Looking at Relay 1, ECU pin 42 is DK green and ECU triggers it to close the relay gate. If you follow that grey wire (+12v) from relay down to Left fan keep going to yellow wire over to top of Relay 3 A2 relay pin down lt blue to Right fan and ground. This is for LOW speed BOTH fans ON in Series. Now when DK Blue ECU pin 33 closes the gate on Relay 2, it also activates Relay 3 gate. Now BOTH fans are HIGH speed running in Parallel with that yellow going to ground thru A1 terminal Relay 3. Right fan lt blu is powered from Relay 2 pin A6 independent (not in series) of left fan & HIGH.
    That can be High speed 1 fan (right) or if DK green ECU pin42 is closing relay 1 at the same time then both fans high. There is no low speed 1 fan. Maybe Relay 3 had the A1 A2 ground mixed up at the start?