peterbilt 387 with ISX engine shuts down on adn off

[Rawze]

(01-30-2018 )Starlight Wrote:  I had this same problem about a year ago. It took me a couple days to go thru and test all the applicable wiring. It was a bad ecm. This guys initial problem was that it died going down the road and somehow had also caused all the gauges in the dash to go dead. It would crank but nothing else worked. The priming pump also didnt work. With a new ecm everything came alive again.

You can usually check this by smacking the top of the ECM hard with the handle of a large screw-driver. The flex-ribbon inside it that folds over the top of the ECM rubs through and shorts out at the top due to years if vibration. I do NOT encourage someone taking the ECM apart though. Most of the time, a person will destroy it when trying to get the cover plate off. This is because glue likes to stick to the cover plate and the ribbon board at the same time, tearing the delicate ribbon board and rendering the ECM a complete brick.

The entire circuit board is nothing but a giant, thin ribbon cable that is very easily damaged with everything printed on it...