2003 Silverado No pcm ground to starter relay

[bradco1]

Hello All,

 

This is my first post here and I have a tough issue. Going to try to give you all info I have.

 

2003 Silverado 1500 Z71 LS

5.3 Engine with Drive by wire

4spd automatic

Manual lever 4 wheel drive

 

I have a no crank condition (starter will not engage)

 

Upon my testing I have confirmed all fuses and relays are good.

 

I have also confirmed that the pink ign wire from under hood distribution is making it to the neutral switch and back out of it via the dark green wire to the starter relay.

 

Power from the key switch is making it through the crank fuse when turning key to crank and has been tested good all the way to the pcm (purple wire)

 

The relay is getting batt power and the bigger purple wire to starter solenoid is good.

 

The only thing not functioning in the circuit is the pcm ground (Y/BLK) to the starter relay.

 

I can probe that wire with ground right at pcm and it will turn over and run. all other wires in this circuit are functioning and it has a new neutral safety switch.

 

so why will the pcm not give ground? I have chase circuits and grounds for days.

We did change the motor in the truck because the other one blew.

No security light is on.

I do keep getting a U1041 Code for communication error to ebcm but thats it.

 

Any help will be greatly appreciated.

[gmtech4]

PCM is toast , i looked at the schmatic,you cant do anything about it

 

programming says to grd that circuit when it gets a request thru the crank circuit ..

 

PCM is done ,make sure that yellow/blk wire is good from D12 to C1 of the PCM

[bradco1]

Thanks for your input on this. D12 to C1 is good. Its funny that I can probe ground to D12 and it starts and runs. Is it common for one thing to quit yet still run vehicle? Not to second guess you it just boggles me. I have been told everything on this from you have to flash pcm for a motor change to I need the engine harness motor came from.....I do not buy that at all.

 

Thanks again.

[gmtech4]

its a driver inside the PCM ,you are merely doing its job and truck starts

 

i would put in a switch to grd from that wire and good to go ,alittle farmish but i had a switch to enable my torque converter clutch on my old 93 C10 lol