Q: chevy tahoe 5.7 pcm voltage output issue

asked by on January 30, 2018

1998 Chevy Tahoe 5.7L pcm not sending triggering signal strong enough to ICM, ICM in turn is not telling coil to fire. crank/no start scenario. fuel ok. CKP ok. CMP ok. checked triggering signal with test light, did not ever light while cranking. checked with multimeter, on crank icm signal wire from pcm gets 3.5-3.8v then dies to 0 when stop crank. ohmed wire, wire ok. checked hall effect manually of CKP. ok, replaced CKP for shits and giggles looked old. PCM 12v feed and ignition feeds ok. whats wrong

My car has 110000 miles.
My car has an automatic transmission.

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Re-check the triggering signal using the specific LED test light described in the instructions at this page. If the LED test light does not flash per those instructions then the PCM would have to be tested further. If the LED test light does flash (while cranking), then carry out the entire procedure outlined at this page and you should obtain a resolution. If you do not, please request a no start diagnostic and the responding certified Mechanic will get this resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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