Scotty,  I am a wrench, been doing it for 35 years so I will understand what ever you say.  I have an 08 Saturn Sky, 2.4L, Manual.  out of the blue I went out turn the key and just get a (relay) click down in the BCM (under pass side dash), not the starter Solenoid click.  pulled out my scanner and I had two codes, A B1325-03 Device power 1 voltage below threshold and B1370-06 Device Ignition 1 Circuit short to ground.

I checked the battery and it was low, like 9.5 volts, so fixed that issue and still the same click.  I cleared the codes and attempted the start again and then checked codes. the B1325-03 was gone.. good.  and the B1370-06 was still present. I actually pulled the starter and benched tested it just to make sure it was good.  I replaced the SDM located Under the center console and still same code, so the SDM not the issue, truly something grounding some where in the "ignition 1 voltage circuit".  I pulled the wiring diagrams and tested for grounds on the "ignition 1 Voltage" wire from the SDM harness plug -back thru the BCM and find that all is good to there, that goes from BCM up to the FUSE block under hood, check from BCM to the fuse block and my ground goes way when i pull the fuse from the Fuse block that the SDM "Ignition 1 voltage" feed wire goes to in the fuse block.  Also checked the Run/Crank Relay (good).  Any idea what is a common cause for grounding between the Ignition and the fuse block ?  

I check the voltage at the physical ignition and it gives me 12.6 volts initially first turn of key to acc, then when I turn it to start/run position it goes to 4 volts.  So I am seeing voltage at the ignition when turning it, but the SDM says it is losing the voltage to ground.  do you have any idea where I can look next? have you seen this before? also do you know what the actual voltage should be at the SDM from The Ignition ?  I cannot find the voltage spec anywhere so I do not know if 4 volts is low or if that is the signal voltage that should be seen at the SDM. 

side note - I am thinking that the Alternator may be bad and that was why the battery was initially low, but I have not been able to start the car to test that.  either way with the battery fully charged and tested as good it should not matter what the alternator is doing until we get the car to turn over.

Thanks, been watching you for years. Gmac