fan wires

Discussion in '94-95 5.0 - Specific' started by ttocs, Jun 6, 2016.

  1. ttocs

    ttocs Legend

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    I installed the Mishimoto fan shroud I had powder coated and then realized I needed to figure out something for wiring. Funny enough they do not have any install instructions. Looking through my wiring stuff shows 3 wires of course, one being a ground and the other 2 coming off of different relay modules. Is it ok to connect to just one of them? I can wire a relay if I knew what the two wires were and what needed to be done. Any help?
    [​IMG]
     
  2. g36 monkey

    g36 monkey Moderator Staff SN95 Supporter

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    Can you get them to go into the factory plug and just reuse the existing wiring?
     
  3. ttocs

    ttocs Legend

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    probably not. Looks like the old plug is mounted to the fan case. I didn't look into it too hard as I was not afraid to cut off the old one and put my own connector on.
     
  4. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    So here's the deal with the factory fan wiring: there are 3 wires as you pointed out. The middle one is ground. The other two are power, 1 is for fan on LO, the other is for fan on HI. The ECU (through the CCRM) energizes one wire when LO is triggered, and then energizes the other (not both) when HI is triggered. So if you are only using 1 wire, then be careful which you use, as you will get only LO or only HI.

    I would assume the Mishimoto fan would have two speeds as well, and use all 3 wires...is this not the case?

    For reference, I am using an aftermarket setup as well, except I have two fans. One fan will come on when LO, and both will come on when HI, using relays and a diode.

    Edit: I have a diagram of how I'm going to do this somewhere...

    Edit edit: Okay, found an old image. But it's not quite what I am doing:

    [​IMG]

    The only change I have made is that where it says "New Relay" I am not running a relay anymore. Instead, I have a heavy duty diode there instead. When the LO fan is on, it will prevent the current flow from reaching the 2nd fan. When HI is triggered, current will flow to both fans. Hope this helps!

    Edit edit edit: Oh, by the way, that's why the fan HI override switch works, because the PCM controls the relays in the CCRM via switching ground. By artificially putting ground in the HI fan input (via a switch) you can force the HI fan on regardless of what the PCM is calling for...
     
  5. ttocs

    ttocs Legend

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    I had kind of figured I would need to do some relay as the mishi fan is just a normal 2 wire fan. Not a big deal as I have relays and by the sound of it can use the power in the harness to trip the relays and the fan so no wires to run.
     
  6. ttocs

    ttocs Legend

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    ok so another question. The ccrm/pcm is just putting 12v out on each high/low wire right? Does the low speed output turn off when the high speed turns on?

    Also here is the guide from my 94 gt oem wiring bible. According to what it says, the black is the ground which in the pic of the harness that I cut off is one of the outside wires. Are you sure that the middle is the ground?

    [​IMG] [​IMG]
     
  7. rz5.0

    rz5.0 Legend

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    I believe so.. At certain temp each one gets power.. I would just get the high speed and set it to come on sooner..

    Sent from my LGLS991 using Tapatalk
     
  8. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Oh good, you have the FSM. Based on that, I think the LO and HI are energized separately, meaning only 1 is on at a time, and not both at the same time. I deduced this based on the wiring diagram you took a pic of (I have the FSM's as well, for my 95) and the fact that my fan HI speed override switch puts the fan on in HI mode. With the fan being completely off, I flip my switch, which puts pin 17 on the CCRM to ground, and the HI speed comes on. It does this *without* the LO speed being on. Thus, they are energized separately (and you'll see in the diagram there that pin 17 feeds the HI relay directly, it does not touch the LO relay).

    As to the wire location, I double-checked on my car, and I was wrong, GND is *not* in the middle. The GND is black, and on one side. Red w/Orange stripe (R/O; fan LO) is in the middle, and Orange w/Light Blue stripe (O/LB; fan HI) is on the other side.
     
  9. ttocs

    ttocs Legend

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    wow thank god I double checked it as I trusted you enough to damn near go with out looking but its always been grilled into me to check my wires prior to connecting. I could not test it electrically so I pulled out the manual and started to wonder.... Now I know what i need to do thanks.
     
  10. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    My bad :( For some reason, I have a mental image of that connector and the black wire is in the middle...obviously I was totally wrong. Usually I double-check before posting something like that, sorry dude :(
     
  11. brad rozum

    brad rozum New Member

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    1994 mustang am also wiring a aftermarket 2 wire fan to be controlled by my ecm. Is it possible to wire the low and the high speed wire to the positive wire on the fan and have the fan run on low and high speed controlled by the ecm or will I have back feed problems?