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  1. #1
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    Sep 2017
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    Default LS3 Wire Harness Connectors

    I bought a cruise and connect package from GM and there are some connectors im not familiar with for my LS swap Chevelle.

    ENGINE HARNESS:
    1. What is the VEH SPD vehicle speed connector used for on LS swap. I plan on using gps speedometer. Does the PCM need this for anything?


    2. GEN connector is only one 16 gauge wire that seems to plug into the alternator. The alternator has 4 pins but the connector only has one wire. The alternator has a single connection on the back that I assume will be for the main harness in the car and for starter solenoid and battery charging.


    3. I have an EOP connector that I assume is for engine oil pressure. Is this actually needed. I will have aftermarket gauges with one for oil pressure. My understanding is if the sensor does not detect oil pressure it will not allow the fuel pump to run??? Is this actually needed or has this been deleted in the programming

    TRANSMISSION:
    Looking at the photos, are any of these wires actually needed. I have a 4L75E electronic tranny.

    1. Can I use the rpm wire for my speedhut gauge?

    thnaks so much for any help!!!

    Perry
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  2. #2
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    Default

    All of this is covered in the documentation you got with your package but here are some answers to the best of my memory embedded below:

    Quote Originally Posted by Zombie666 View Post
    I bought a cruise and connect package from GM and there are some connectors im not familiar with for my LS swap Chevelle.

    ENGINE HARNESS:
    1. What is the VEH SPD vehicle speed connector used for on LS swap. I plan on using gps speedometer. Does the PCM need this for anything?

    It is an output intended to drive a speedometer. If you donít need it donít connect it.

    2. GEN connector is only one 16 gauge wire that seems to plug into the alternator. The alternator has 4 pins but the connector only has one wire. The alternator has a single connection on the back that I assume will be for the main harness in the car and for starter solenoid and battery charging.

    Correct

    3. I have an EOP connector that I assume is for engine oil pressure. Is this actually needed. I will have aftermarket gauges with one for oil pressure. My understanding is if the sensor does not detect oil pressure it will not allow the fuel pump to run??? Is this actually needed or has this been deleted in the programming

    I used the stock oil pressure sensor so I canít help you on this one. Check your documentation.

    TRANSMISSION:
    Looking at the photos, are any of these wires actually needed. I have a 4L75E electronic tranny.

    The A/B wire enables selection between economy and sport transmission modes. Check your documentation.

    The brake wire is normally connected to the brake light switch. Again check your documentation.

    The manual shift connections are for tap shifters if i recall. If you donít have tap shifting then donít use them.

    1. Can I use the rpm wire for my speedhut gauge?

    Yes. You will likely need a 4.7kohm pull-up resistor connected to 12 volts.

    thnaks so much for any help!!!

    Perry
    1969 Camaro - LSA 6L90E AME sub/IRS
    1957 Buick Caballero - huge project
    1959 El Camino - Ironworks frame
    1969 Mustang Sportsroof
    1956 Cameo - full C5 suspension/drivetrain

  3. #3
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    Aug 2004
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    Jacksonville, FL
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    The VSS plug is critical for an auto I believe. The GM OP sensor does work with CAN gauges, using them on my DD gauges on my LS3 GMPP harness. Are you using the bulkhead connector for the trans signals?
    Chris
    1968 Chevy Camaro SS
    LS3/T56 Ridetech suspension


  4. #4
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    Sep 2017
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    Default

    Thanks guys, this was very helpful!!

    Chris,
    Does the VSS sensor plug into the tranny? If it does, then I shouldn't have an issue using my gps speedometer, right?

    Perry

  5. #5
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    Perry, yeah you need to plug the VSS plug into the transmission. Which TCU are you using? You should be able to use the bulkhead connector and connect that to your TCU. The PCM needs the vss so Hank in an auto application. If you are using a GPS antenna for your speedo then it will be totally separate. Which gauges are you running?
    Chris
    1968 Chevy Camaro SS
    LS3/T56 Ridetech suspension


  6. #6
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    My mistake on vehicle speed connector. I thought you were referring to the VSS output, not the VSS input connector. Sorry for the confusion.

    VSS output is the orange speed wire in your pic.

    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1957 Buick Caballero - huge project
    1959 El Camino - Ironworks frame
    1969 Mustang Sportsroof
    1956 Cameo - full C5 suspension/drivetrain

  7. #7
    Join Date
    Sep 2017
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    48

    Default

    Chris,
    The gauges I'm using are speedhut model GRM338-6KITGPS-01. I slap have couple of other queries:

    1. In the photo you can see a connector with a blue end. This is the EOP engine oil pressure. Since my gauge kit comes with an oil pressure sensor, how do I make the gauge work. Does the PCM need to see oil pressure for it to work.

    2. The last photos show a number of connections. The top one is the OBDII port, pedal is obvious. What is the MIL connection for and finally, can I use any unused switched power sources for the IGN SW connection.

    Thanks again for the help!!
    Perry
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  8. #8
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    MIL is the malfunction indicator light or check engine light.

    Any line that is hot while cranking can be used. The wires are generally pink...

    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1957 Buick Caballero - huge project
    1959 El Camino - Ironworks frame
    1969 Mustang Sportsroof
    1956 Cameo - full C5 suspension/drivetrain

  9. #9
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    Aug 2004
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    Jacksonville, FL
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    Perry, GMPP pcm does not need the oil pressure sender to operate. Just use the OP sender that came with your gauges. If your sender is not metric, you will have to get an adapter fitting. Same for the temp gauge. The PCM does need water temp, most use the drivers side head sensor for the PCM and the pass side for your new gauge sender. That MIL wire is the light for your check engine light. The PCM sends a “ground” signal when it comes on. What you have to do is connect one side of whatever light/led you are going to use with ign power and then the MIL wire on the other side of the light circuit.
    Chris
    1968 Chevy Camaro SS
    LS3/T56 Ridetech suspension


  10. #10
    Join Date
    Sep 2017
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    Default

    Fantastic everyone. Really appreciate the help. I am good to go.



    Perry




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