No crank no start

GMC guy

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#16
I jumped 30 to 87 on relay socket and the starter turned over quite strong. I sat in the car and turned ignition and i heard the starter prime. Checked pressure at port. Good pressure. Jumped relay socket again. Still no start. Did the 10 minute relearn and still no start.
 

GMC guy

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#18
I scanned it and po315 came up several times. Im not sure about this because i just changed the computer. And the car has not run yet, so i dont know if this is accurate although fitting.
 

grcauto

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#20
Theft system?? Did you program the PCM? If you are trying to do a crank sensor relearn you MUST use the scan tool.
 

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#21
Theft system?? Did you program the PCM? If you are trying to do a crank sensor relearn you MUST use the scan tool.
No, i put another pcm/ecu in to see if it would start. I just got codes that were on it. The original pcm didnt have any codes.
 

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#22
I put the original pcm back in the car. The little red light is off for the security system and there is no check engine light on. The smoke is beginning to come outta my ears
 

grcauto

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#23
Does it start? If not and the PCM is the problem the new PCM will have to be flashed with the VIN or it'll never run.
 

billr

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#24
Do I understand correctly, the engine cranks if you jumper the relay, but not with key? The fuel pump comes on if you jumper its relay, but not with the key?

We need a schematic of the wiring around the ignition switch, we will keep wandering in circles until that is available. If nobody posts one soon, consider buying it via Alldata, Chilton's, Hayne's, etc and posting it here yourself.
 

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#25
Do I understand correctly, the engine cranks if you jumper the relay, but not with key? The fuel pump comes on if you jumper its relay, but not with the key?

We need a schematic of the wiring around the ignition switch, we will keep wandering in circles until that is available. If nobody posts one soon, consider buying it via Alldata, Chilton's, Hayne's, etc and posting it here yourself.
Yes, all that but not with the key.
 

billr

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#26
It was mentioned in another thread that much of the Alldata resource is now available for free on the Auto Zone website. I tried looking for a "sample" schematic earlier and wasn't successful, but may try again for your vehicle. You should try too, maybe you are better with the computery stuff than I am.
 

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#27
It was mentioned in another thread that much of the Alldata resource is now available for free on the Auto Zone website. I tried looking for a "sample" schematic earlier and wasn't successful, but may try again for your vehicle. You should try too, maybe you are better with the computery stuff than I am.
 

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billr

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#28
OK, that gives us something to talk about. It is rather ambiguous, but let's try. Since you have a relay, I am assuming the "MLQ" path in that circuit is the one that pertains. Have you located the "30A ACC/IGN1" fuse and verified there is 12V on both terminals of it while trying to crank?

What's shown is a pretty simple circuit. If you do have 12V on both sides of the fuse, then it is time to locate the ignition switch and see what in/out voltages there are.