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Thread: Probing 'unused' ECM pins

  1. #1
    Tuning Addict blindsquirrel's Avatar
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    Probing 'unused' ECM pins

    I'm building a bench harness to go a-pokin' around at unused pins to see if anything interesting shows up. Don't want to fry anything if I can help it. Anybody have safety tips? I don't know how useful it would be to check first for voltage/ground, as the pins could have pullup/pulldown resistors inside and might lead me astray. An unused signal pin probably won't be truly isolated from everything on both sides.

    What's the 'safe' way to check them? Jumper a 5v source through some value of resistor?

  2. #2
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    Quote Originally Posted by blindsquirrel View Post
    I'm building a bench harness to go a-pokin' around at unused pins to see if anything interesting shows up. Don't want to fry anything if I can help it. Anybody have safety tips? I don't know how useful it would be to check first for voltage/ground, as the pins could have pullup/pulldown resistors inside and might lead me astray. An unused signal pin probably won't be truly isolated from everything on both sides.

    What's the 'safe' way to check them? Jumper a 5v source through some value of resistor?
    Were you able to try anything on this?

  3. #3
    Tuning Addict blindsquirrel's Avatar
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    Nah never went any further. Being that reading a voltage would be dependent on both the OS supporting it AND having some kind of PID defined for it in the scanner, odds of finding anything would be extremely low.

    My E40 even has one for the brake booster sensor that reads just fine in other scan tools, but there's no PID for it in the HPT scanner. Support said they'd look into adding it but since that was like 2-3 years ago it'll never happen.

  4. #4
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    Ahh!
    Ive got a couple E38s if you wanted to use them and if you fried them then no loss.

  5. #5
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    Quote Originally Posted by RDF1 View Post
    Ahh!
    Ive got a couple E38s if you wanted to use them and if you fried them then no loss.
    I've already probed and traced lobotomized E38.

    E38 Complete Pinout.pdf
    2011 Cadillac Escalade L94 w/LS3 valves and valve springs