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I finally got a Cat C15 to fire up by ditching the ECM flash entirely
Had a 2006 Pete with a C15 that just would not start no matter how many times I reflashed the ECM. Everyone in the shop kept telling me it had to be a ground issue or a bad crank sensor. On a hunch I bypassed the ECM and jumped the fuel shutoff solenoid directly off a 12V test lead at the battery box, and she fired right up. Turned out the ECM had a internal power supply failure that was killing all the fuel commands. Has anyone else seen ECMs that pass diagnostics but still drop the fuel signal like that?
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grace891mo ago
That "passed diagnostics but still dropped the fuel signal" part really got me. I had the exact same headache on a 2005 C15 last summer. New ECM from the dealer, reflashed it three times, all the voltages checked out, and it still wouldn't send fuel commands. Ended up putting a breakout box on it and watching the injector driver lines while cranking - dead silent on the scope. The ECM was telling the diagnostic tool it was fine but physically wasn't doing anything.
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shanelee1mo ago
Man I had a buddy chase that same ghost on a Cummins for three weeks.
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the_anthony1mo agoMost Upvoted
That 2005 C15 tricking the diagnostic tool while being dead silent on the scope is a hell of a find. I’ve had ECMs lie before but never that cleanly, usually they’ll flicker a ghost signal or throw a code. Did you ever figure out what internal failure was causing that disconnect, or did you just swap in another ECM and call it a day?
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