No start 2001 chevy 8.1 fixed

billr

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#31
Just for reference when you are checking, I read that schematic as showing the following minimum connections are needed to wake the PCM and get FP action at key-on:

PCM pins 1 and 40 => GRD (probably only one needed)
PCM pins 20 and 57 => B+ ("always hot" 12V)
PCM pin 19 => switched 12V (this is key-on signal)
 

nickb2

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#32
I'm thinking the vehicle will continue to run if it loses the cam signal but will not start without it. I'm going by memory but it seems this was true with some GM platforms of that era.
True. GM has a fail safe for cam loss signal.
 

autojoe

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#35
Just for reference when you are checking, I read that schematic as showing the following minimum connections are needed to wake the PCM and get FP action at key-on:

PCM pins 1 and 40 => GRD (probably only one needed)
PCM pins 20 and 57 => B+ ("always hot" 12V)
PCM pin 19 => switched 12V (this is key-on signal)
Will check out. Thank you
 

autojoe

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#36
Have rpm signal while cranking and cam and crank counts but no spark or injector pulses. Fuel pump will run and pressurize the rail if take a test light and touch fp relay control wire at pcm. Going to check pcm powers and grounds as billr stated. Thanks to everyone for their help.
 

billr

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#37
Be sure to check for the FP drive (12V) at PCM pin 9 when you do a "key-on" by applying 12V to pin 19.
 

autojoe

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#39
IMPORTANT: A missing Camshaft Position (CMP) sensor may cause a long crank condition.

The CKP signal must be available for the engine to start. The CMP signal is not needed to start and operate the engine. The PCM can determine when a cylinder is on either the firing or exhaust stroke by the 24X signal.
Now it is showing cam and crank counts and rpm. No spark or injector pulses.
Maybe connectors were not seated. Receiving cam, crank and rpm signal while cranking. No spark or injector pulses. Going to do tests like billr described and check the power and grounds at pcm. Thanks for everything. Joe
 

nickb2

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#40
This thread sadly sounds like it going towards a bad PCM if all connectors are seated well. Maybe a driver or two went south in the control module. So pinout testing is essential here.

Here is a pinout of pcm and all associated. Hope it helps.
 

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autojoe

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#41
This thread sadly sounds like it going towards a bad PCM if all connectors are seated well. Maybe a driver or two went south in the control module. So pinout testing is essential here.

Here is a pinout of pcm and all associated. Hope it helps.
Thanks nickb2 someone gave me one earlier. I love the Mitchell pro demand vs alldata but I noticed that on the Mitchell diy site where you pay per vehicle it is different format then the on demand or pro demand. I do have Mitchell on demand that I bought off ebay with the laptop several years ago for around 400. Goes up to 2014. I don't know the difference between on demand and pro demand. Pro demand they want subscription 150 per month for 1 year. Too much money for me. Thanks to everyone. Joe will post back what I find out.
 

autojoe

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#42
This thread sadly sounds like it going towards a bad PCM if all connectors are seated well. Maybe a driver or two went south in the control module. So pinout testing is essential here.

Here is a pinout of pcm and all associated. Hope it helps.
Thank you