electric fan - mechanical replacement

Discussion in 'Chevy C/K Truck Forum' started by K15 Blazer Guy, May 26, 2013.

  1. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    yeah, it just pulled whatever it wanted out of the battery. there were 2[hot] wires comming off the fan, one for the 4,000+ cfm and 40+\- amps, and one for about half that... i wired it to the lower speed first, and thats all it needed. these trucks have nice huge radiators and big gaping grilles, so it never went above 210. i would even switch it off on the highway if i knew i wasnt going to be in any traffic.

    as soon as i call summit and get the relay matched with the fan i want, i post pics of the install.
  2. nonnieselman

    nonnieselman Member 1 Year

    what vechicle are we talking about here??

    ive put LS1 and LT1 Efan setups on the older trucks 1993 and a 1998. Wired it up series/parallel like the Camaro, corvette and 2005-2007 GMs have theirs. PCM control low and high.
  3. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    my 93 k1500
  4. nonnieselman

    nonnieselman Member 1 Year

    Oh we had put 5.3 in both them trucks. But for a 93 the LT1 or LS1 Efans will still fit with brackets.
    I like the OEM fans. Really easy to get motors for incase one dies on a road trip or something.
  5. BillM

    BillM Rockstar 100 Posts

    What PCM are you talking about? Does my PCM on my 2003 Tahoe Z71 have fan controls? Which terminals do I use? Do you have an electrical diagram that shows those PCM contacts? Thanks.
  6. nonnieselman

    nonnieselman Member 1 Year

    Yep. Here is theSchematic


    I dont like hookin it up to the AC wire like that shows. Run it to the pcm and let it do all the work.

    This works on 1999-2007classic.

    I gotta copy and paste a play by play and it helps noobs get into wiring.

    [COLOR="silver"]- - - Updated - - -[/COLOR]

    Efan wiring 101

    How to make your own efan harness pick one of the two ways.

    Example #1
    You need two 40 amp relays that have atleast 4 pins. You can use 5 pin relays if need be.
    12 or 10ga wire for the power and ground
    18ga wire for the trigger
    Either 1/4" spade connectors or relay sockets
    Ive used crimp on spades but i perfer to solder the wire to the connector just for the heck of it. And heat shrink it.

    Use 12 or 10ga wire on pins 30, 87, and 87A.
    Use 18ga on pins 85 and 86.

    This is how i wired the LS1 fans on my buddys 1980 4x4 with a LS 408ci and the factory 1980 radiator. Fan 2 very rarely comes on unless he is running it hard in 4 Low.
    If you go by this, you can add another wire in all the Pin 85's and run it in the cab, hook to a switch. Ground the other leg of the switch and you have a manual override to turn the fans on.
    This will only tell you when the PCM or manual override is commanding the fans on:
    You can also wire in a LED on this wire. Put 12V+ on the hot side of the LED and connect the ground wire to the wire off PIN 85. When the PCM or your manual override switch is activated you can see by your indicator.

    This way lets you know that all your fuses and relays are In working order.
    Wire in LED where the positive side is connected to Relay #1 PIN 87. Ground the other side. This lets you know the relay has power and is sending it to Fan #1.
    For Fan #2 hook the positive side of LED to either Relay #2 pin 87 or Relay #3 pin 87A. Ground the other wire of LED.

    Relay #1
    30 12 volt + with atleast a 30A fuse
    87 positive side of Efan #1
    85 PCM pin 33
    86 12 volt + *(ive soldered in a 18ga wire into the connector of pin 30, saves a lil wire and a fuse, to power the trigger. Instead of running another wire all the way to your power source. I did this on all the relays. Do as you like. )

    Relay #2
    30 12 volt + with atleast a 30A fuse
    87 positive side of Efan #2
    85 PCM pin 42
    86 12 volt +

    This is how i have the 2005 34" Efans wired on my 2000 Silverado.

    Relay #1
    30 12 volt + with a 40A fuse
    87 positive side of Efan #1
    85 PCM pin 42
    86 12 volt +

    Relay #2
    30 12 volt + with atleast a 30A fuse
    87 positive side of Efan #2
    85 PCM pin 33
    86 12 volt +

    Here is where you need the 5 pin relay
    Relay #3
    30 Run Fan #1 ground to here, dont ground it anywhere else
    87 Ground to frame, block, or battery. Any good ground.
    87A Fan #2 positive side
    85 Splice into the PCM Pin 33 wire. Or you can run a wire from Relay #2 pin 85
    86 12 volt +

    Now get to work!!

    I used a 6 circuit fuse block mounted to the rear of the factory fuse box that i ran a #6 wire from the red power box on the driver side for power and a #6 wire for the ground strip on the fuse block to the engine block.
    That way the fuses are easy to get to and gives you plenty of space for other accessories that need a fuse or a good ground.

    When i get some more time where i can think ill try and do a writeup on how to troubleshoot a EFan harness problem.[/QUOTE]

    ope this works im on my phone.
  7. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    finally got the parts! =)

    going to install this weekend along with a K&N intake I scored for free! XD

    so ill be posting pics next time I have my camera on my desk.
    the challenging part is going to be getting the fan to mount in the stock housing, because its 2 pieces.... but I got some ideas.
    wish I could dyno it before and after
  8. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    forgot my camera... but here it is installed.
    fit in the stock fan shroud with 2 wooden poles and wired up with a discreet low amp blue switch on the dash.
    throttle response and MPG have improved significantly
    IMG_0128.jpg IMG_0125.jpg
  9. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    Looks great. Give us an update on how it does with some miles and different conditions.
  10. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    so far its great. I drove 50 miles yesterday. didn't need to have it on for freeway speeds.
    stayed below (what I assume) is 190 around town sitting in traffic.

    so far no heat waves, but in stop and go traffic with the AC at full blast will be the ultimate test. but no real concerns about that =)

    if it does require a little more help... ill figure out some material to fill in the gap around the edge of the fan, and the shroud.
    its a 3,000 CFM fan.... is the factory mechanical fan more or less than that?

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