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1999 grand cherokee limited, 4.7

Discussion in 'Grand Cherokee' started by glassport, Mar 15, 2019.

  1. Mar 15, 2019 at 9:25 PM
    #1
    glassport

    #1
    glassport [OP] Member

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    Someone please tell me I'm wrong, give me other options. I attached copy of map circuit diagram. Engine lite came on, checked codes, only one was p0108 map signal to high. Checked sensor, I verified pin 2 is ground, diagram shows pin 1 is 5v source from ecm, pin 3 is signal to ecm. Key on engine off have 5v on pins 1&3. Started engine had 5v on pins 1&3, hmmm. Turned engine off, pulled plug off of map sensor, holding plug in hand (plug not connected to map sensor), had 5v on pins 1&3. Please give me an option other than chasing a short. Is there anything else it could be?
    Thanks in advance for any and all help.

    Read more at: https://www.obd-codes.com/forums/viewtopic.php?f=20&t=18170Copyright OBD-Codes.com

    jeep map dia.jpg
     
    glassport, Mar 15, 2019
    #1
  2. Mar 16, 2019 at 8:18 AM
    #2
    Awrench

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    Awrench Well-Known Member

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    unplug connector at PCM - did voltage on signal K1 wire go to 0zero?

    my guess a short to voltage on circuit K1.
     
    Awrench, Mar 16, 2019
    #2
  3. Mar 16, 2019 at 8:49 AM
    #3
    glassport

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    glassport [OP] Member

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    I'll try that, thanks.
     
    glassport, Mar 16, 2019
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  4. Mar 16, 2019 at 9:26 AM
    #4
    glassport

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    glassport [OP] Member

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    Got to thinking about it, if K1 is shorted to K7, K6 or any other feed from pcm I'll lose the 5v feed.
     
    glassport, Mar 16, 2019
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  5. Mar 16, 2019 at 9:49 AM
    #5
    Awrench

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    Awrench Well-Known Member

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    more often shorted to a separate circuit,
    you could check k1 to k7 when unplugged for continuity,
    circuit for k6 is C2 and the 5v would show a the short I think we etting ahead of the plan.

    I thik I would double check the connector to sensor.
     
    Awrench, Mar 16, 2019
    #5
  6. Mar 17, 2019 at 6:16 PM
    #6
    glassport

    #6
    glassport [OP] Member

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    Unplugged C1 at pcm and no voltage on K1 or K7. Had continuity on K1 between map sensor plug and C1, had continuity on k7 between C1 and plug at map sensor, no continuity between K1 and K7infinite ohms. If there is no short does it leave anything but pcm?
     
    glassport, Mar 17, 2019
    #6
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