K2500 ABS Module Help!

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Supporting Member
Supporting Member
Jul 17, 2020
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How do I find the brake option code? Sorry

Thanks I will have to try the 2 man method, I did something similar but I left a few steps out so I’ll give it a shot.

So did some digging and found a trouble shooting guide to diagnose the vacuum booster.. This is after engine was running at idle for a few minutes and then I pressed the brake pedal and released it once. Seems like I have a faulty booster since it’s causing a misfire?

Also when I turn truck off after idling for a few minutes while holding the brake pedal down, it does not stay down. What I was reading said to hold the brake pedal down for 30 seconds after turning the truck off and release, and supposedly they should not move. Mine move instantly even with my foot pressing them down.
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Look in glove box at sticker showing RPO codes.