Expert: Sean Halliday - 9/2/2007

Question
QUESTION: Engine won't run or communicate with Snap-On brick, customer's truck towed to shop 2 weeks ago (won't start), I found engine very low on oil, that's why I thought it wouldn't start then. Truck ran fine, while setting in shop for trans repair o'k (maybe 5 days) It would not start! Then same as first time will not communicate with scanner, also no glow plugs or any clicking under hood, no solenoids nothing, but all fuese are good, no fuel pump power. Anyone have a clue as to where I should look? (power to lights horn etc.)

ANSWER: I assume the obvious battery tests were done but this one is a process of elimination for the electrical fault.Try the relay for the ignition and injection system.Check also the cam sensor as i know these go out.

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QUESTION: Yes sorry I didn't state that before, new batteries, and new cam sensor, truck was running fine,engines cranks, just won't fire. No power to fuel pump & solenoids, plus won't communicate to scanner, it did this before when I found engine low on oil, I filled tried it and it started (a week ago) so I thought it was fixed till Friday, when I tried to start it again. Can the ECM come & go like this or power modual do the same & how can I test

Answer
Anything is possible to go out as its electrical.It doesnt have an inertia switch by chance ?Thats the fuel cut off/safety switch.Or the alarm system which i have seen go faulty.Rare to see the ECM fail.Best way to test is,check power is going in to the ECM and then if its going out with a meter.You will need the wiring diagram.Intermittent faults are hard to find and theres no way to tell unless you do the process of elimination.