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+--- Thread: why RPM drops (/showthread.php?tid=7854)
why RPM drops - alborz - 11-20-2021
2015 pererbilt 579
ISX 2350
500 k miles
recently it happens several times that after starting the truck the rpm gauge falls down to zero although the engine is idling.then the orange engine light comes on. if I turn off the truck and restart it again it is as it should be.
I'm wondering if there is sensor going bad or a something else.
your input greatly will be appreciated.
RE: why RPM drops - Signature620 - 11-20-2021
If the engine light comes on then there will be faults stored in the ECM. Plug into it and check instead of guessing. Could be data link related.