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Thread: PCM Bench Harness Build

  1. #1
    Carb and Points!
    Join Date
    Sep 2019
    Age
    46
    Posts
    7

    Lightbulb PCM Bench Harness Build

    If anyone would like to share their experience with building one of these please by all means do.

    I grabbed a set of PCM connectors and an OBDII port at the salvage yard and I am going to build a bench harness.

    96 Grand Prix GTP-#16211539, with the 3.4L DOHC.

    Connector one PCM C1 BLUE
    PIN#19 Power Ignition (Pink) *Hot in RUN*
    PIN#20 Battery (Orange) *Hot At All Times*
    PIN#21 PCM Ground (Tan/White)
    PIN#59 DLC Class 2 Data (Purple)
    PIN#60 PCM Ground (Black/White)
    PIN#68 Power Ignition (Pink) *Hot in RUN*

    **May Not be Required**
    Connector two PCM C2 CLEAR
    PIN#21 PCM Ground (Black/White)
    PIN#60 PCM Ground (Tan/White)

    Two 12v switches w/LED, <=> 2Amp Fuse Holder <=> Connected to Bench Top Power Source @12V 1amp
    Switch (LED) #1 <=> 2Amp Fuse <=> PIN#20 (Hot at all times)
    <=> OBD2 Data Connector PIN#16
    <=> (To switch #2)<=>
    Switch (LED) #2 <=> PIN#19 (Hot in Run)
    <=> PIN#68 (Hot in Run)

    *All Grounds to ground of the 12v power supply.

    OBDII Data Connector
    PIN#2 <=> PIN#59 DLC Class 2 Data (Purple)
    PIN#4 <=> Ground
    PIN#5 <=> Ground
    PIN#16 <=> 12V 2Amp Fuse <=> Switch #1

  2. #2
    Fuel Injected!
    Join Date
    Dec 2013
    Posts
    77
    This is the Bench harness i use to read ALL 99 to 06 PCMs (Gen 3), 4Cil (ecotec Blue/clear), V6 (Blue/clear) and all V8 (Blue/Red, Blue/Green).

    Connector one PCM C1 BLUE
    PIN#19 Power Ignition *Hot in RUN*
    PIN#20 Battery *Hot At All Times*
    PIN#1 PCM Ground
    PIN#58 DLC Class 2 Data
    PIN#40 PCM Ground
    PIN#75 Power Ignition *Hot in RUN*

    OBDII Data Connector
    PIN#2 <=> PIN#58 DLC Class 2 Data (Purple)
    PIN#4 <=> Ground
    PIN#5 <=> Ground
    PIN#16 <=> 12V *Hot At All Times*

    That's it, Maybe you pcm different? or where do you get the diagram?
    Last edited by NISANDA; 10-02-2019 at 10:36 PM.

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