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Thread: PCM and ECU Location

  1. #1

    Default PCM and ECU Location

    I have a 1999 Jeep Grand Cherokee Limited with the anti theft system. My jeep was bought to a mechanic because my car would crank but not turn over, no fuel pressure and no power to the fuel pump. I put a new fuel pump in, new battery terminals, firestone put in a new battery and cam shaft sensor and the same thing is still happening it won't start. It towed over to a dealer and dodge told me my pcm is bad because their equipment wouldn't even read it. A new part costs $957 and I don't have that right now to spend. So I bought a used one from a junk yard, its comes with the ecu and pcm and all the part numbers match up, and both had an anti theft system, they told me I should have no problems and it should start up right away. My question is based off the location of the ecu and pcm on my jeep, and will I have to take any parts off to get to them. If you could possibly help me out with detailed instructions it would mean a lot.

    Thanks again,
    Tony

  2. #2
    Registered oldgeezer's Avatar
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    It's on the firewall on the passenger side. Expect to have to remove the coolant reservoir to work on it. Maybe the attached diagram will help.

    EDIT: For future reference, the ECU is the same as PCM; ECU is not a separate device.
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    2001 WJ Limited, 4.7L, Quadra-Drive -- Kenne Bell Supercharger, Stillen Rotors with MM pads (F/R), Addcos (F/R), Kolak 3 inch exhaust with large case MagnaFlow, Rogue Chrome wheels, DRL activated, and Blaupunkt 3.5" dash speakers.

  3. #3

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    I actually have the inline 6 engine with 4.0 L will that make a difference, so it's under the hood I take it, or on the inside?

  4. #4
    Registered oldgeezer's Avatar
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    It's always best to give that kind of info in your original post, but in this case it doesn't matter.

  5. #5

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    if you plan to disassemble it you should make sure your body is grounded somehow, to avoid destroying electronical componets within the PC board.

  6. #6
    I need e-help..
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    I don't believe that one can just swap PCMs in a WJ.

    The replacement PCM must be reprogrammed with the WJ's VIN and odometer mileage. Also, the remote keyless entry fobs will need to be reprogrammed to match the new PCM's security codes.

    -Kyle

  7. #7
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    go here....join for free....and enjoy the documents


    http://www.jeepslimited.com/index.ph...tpage&Itemid=1
    04 WJ, SE, 4.0L , Appco rear 1" swaybar. 5600 miles!!!!!!!!!!!!!!!!

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