PCM is staying awake causing 4.5 amp draw - Page 2
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Electrical Technical Information Discussion, PCM is staying awake causing 4.5 amp draw in Item Specific Cadillac Discussion; Update: Still dealing with this, just pulling the PCM Batt fuse under the hood when the car is sitting for ...
  1. #16
    Avaya is offline Cadillac Owners Member
    Automobile(s): 2001 Deville DTS
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    Re: PCM is staying awake causing 4.5 amp draw

    Update: Still dealing with this, just pulling the PCM Batt fuse under the hood when the car is sitting for very long. I put in a few minutes here and there, the car is half apart with with back seats out and steering column all exposed.

    Summary: I have a total parasitic draw of 4.85 amps which occurs through about 14 fuses and some relays. If I pull the PCM Batt the draw drops considerably.

    I had a break through last night messing around: The horn turns on the interior lights, and they shut off when horn is done. When parked, the horn turns on interior lights, unlocks the doors, and pops the trunk. (ha, yeah I can laugh at it) I am excited because to me this means there is a group of wires that is crimped/ burned/ wet or something. All I need to do is trace the horn wire and find the break and that should be the fix. Any advice as to where (physically) the horn wire runs?

  2. #17
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
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    Re: PCM is staying awake causing 4.5 amp draw

    Horn is involved with several circuits.

    You will need a few circuit diagrams. Subscribe the car - multi-year - to www.alldatadiy.com
    Avaya likes this.

  3. #18
    Avaya is offline Cadillac Owners Member
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    Re: PCM is staying awake causing 4.5 amp draw

    Thxs Submariner409, done and done, gonna spend some time under the dash tonight

  4. #19
    Avaya is offline Cadillac Owners Member
    Automobile(s): 2001 Deville DTS
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    Re: PCM is staying awake causing 4.5 amp draw

    Ok, mostly have this figured out now, and it is a weird conclusion.

    I disconnected the PASSKey III Immobilizer Module : https://www.directedstore.com/manuals/555gw.pdf
    It looks like this: http://www.amazon.com/Directed-Elect.../dp/B0036NFIVY
    From what I can tell, it was only in years 00 and 01 deville, and some sevilles.
    It disables the PASSkey III when using remote start. It is located under the steering wheel, under all the removed paneling.
    I'll eventually have to fix it if I want to use the remote start, but doubt I ever will.

    I was drawn to it by the crappy wiring job, it didn't look factory.
    I unplugged it and all the draw is gone, AND the PRND321 light on the dash turned off.

    The ground and remote power were not connected to the module, and somehow it was keeping something awake, thus keeping the PCM awake, thus keeping lots of things awake. I don't think I'll fully understand, but as long as the draw is gone.

    Now to put things back together. Interestingly enough, the horn still does the lights, locks, and trunk, so must be a separate issue.

  5. #20
    Avaya is offline Cadillac Owners Member
    Automobile(s): 2001 Deville DTS
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    Re: PCM is staying awake causing 4.5 amp draw

    uhh, OK, it wasn't that easy

    It ran, but the security light was on. I checked codes and cleared them all, and it wouldn't start, turns out key was disabled.

    Also turns out, the module's ground was the only problem, not the remote power too.

    I couldn't just unplug the above module, it created a break in one of the lines from the ignition. I had to find where that wire was "cut" or broke and took out the module and put the ignition wire back together. Now it works.


    Soooo.....bottom line is: all my parasite draw and symptoms were caused by a disconnected ground to the PASSkey III Immobilizer Module. That, on my car is located under the driver's side kick panel, yours may be different because it appears that this Viper remote system was dealer installed.

    Out

  6. #21
    Maxwell Power is offline Cadillac Owners Member
    Automobile(s): 2005 CTS-V
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    Re: PCM is staying awake causing 4.5 amp draw

    wow.
    I'm dealing with a similar issue (parasitic draw) in my 05 CTS-V. I don't have any aftermarket wiring of any sort, however.

    Very happy you got it figured out. These type of gremlins are one of the most annoying. Ever figure out the horn/lights thing?

  7. #22
    Avaya is offline Cadillac Owners Member
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    Re: PCM is staying awake causing 4.5 amp draw

    Quote Originally Posted by Maxwell Power View Post
    wow.
    I'm dealing with a similar issue (parasitic draw) in my 05 CTS-V. I don't have any aftermarket wiring of any sort, however.

    Very happy you got it figured out. These type of gremlins are one of the most annoying. Ever figure out the horn/lights thing?
    Nope, but haven't looked either, I just don't honk the horn, ha!

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