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Thread: 2017 e78 truck ecm flex fuel pin

  1. #1
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    2017 e78 truck ecm flex fuel pin

    I?m trying to add the physical flex fuel sensor to my 2017 2500hd truck. It is a flex fuel truck but used the garbage virtual setup. I have a gm sensor and pigtail. Obviously I have the power and ground of the sensor hooked up, but I need to know which pin on the e78a ecm is the flex fuel signal pin? I?m finding different answers for different model cars that use that ecm when searching the web

  2. #2
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    Take a look at the GM upfitter manuals, there is a lot of good info in those manuals, and you can probably find it there.

  3. #3
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    I don?t have access to those I don?t believe

  4. #4
    I would think pretty much anyone can access the upfitter manuals.
    Not sure if ecm pinout is with their diagrams/schematics, but worth a look.
    Other valuable information there regardless.
    https://www.gmupfitter.com/pages/body-builder-manuals

  5. #5
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    I didn?t know I could see them! Thank you! Unfortunately, I didn?t find anything about flex fuel

  6. #6
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    I?m going to assume I have it wired right, as I enabled sensor diagnostics and the two codes associated with the sensor and have not had a check engine light yet. I used pin 34 I believe on the x3 connector

  7. #7
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    Monitor alcohol % in the scanner and see what it reads.

  8. #8
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    It is working correctly