Been through the various key/security issues, then worked through the steering lock issue, and now fighting BCM no comm issues and car won’t start. Last time simply swapping out the TDR relay worked, this time tried everything I can find from you guys, including all Bills write ups. I pulled and checked fuse 25 fine, replaced relay again, checked every ground I could find, unhooked battery, tried both keys, checked connections in door accordions, etc. What’s weird is normally something else isn’t working if it’s BCM, but literally everything in the car works, plenty of power and lights, but turn the key to start and everything goes black. Car is literally like new in terms of condition so no excess wear or moisture or anything. Here are the codes it threw: PCM P1575H, extended travel brake switch circuit high voltage, LDCM B2264H vertical position sensor fault, LDCM U1064H and RDCM 1064H loss of communication with BCM, and SCM No Comm (which is fine have race seats).
I’m stumped once again and these little electrical gremlins are killing me. Any other suggestions would be appreciated! Thanks very much.

 

If the car goes “black” when the key is started you probably have high resistance somewhere in the starting circuit...have you gotten UNDERNEATH the car and cleaned the positive side of the battery cable down at the starter solenoid ??...a visual check isn’t good enough...wire brush everything including the engine block (ground side) and solenoid and reinstall..same with the negative battery cable...before doing any of this try taking a jumper cable and connect one side to the negative battery terminal and the other to a good clean spot on the engine...now try to start the car...if it starts you have high resistance on the ground...if you have a test light connect it to battery negative and while cranking touch the tip to the engine block..if light illuminates you have a bad block ground !!...and another thing get your battery load tested !!

 

When you say no start, you have to specify if the engine cranks over but fails to start, or no start means no cranking, which is what I deduce from your post. First of all as it's already advised is to have your battery load tested and make sure it's good. All cars go black when you turn the key to start because power is switched off to indicators and systems not needed to start your car, that is done so power is conserved to crank the engine. Do you hear the TDR relay click when you turn the key to start? If proficient with multimeter, connect positive meter lead to "s" terminal on starter solenoid "violet" wire and negative lead to battery negative terminal or any good ground point, check for 12 volts when you turn the key to start if present then your starter solenoid will have to be replaced.

 

Any update on your no start problem, there is one thing you might try to help pin point what the problem is. Take a heavy gauge jumper wire and place it in the TDR socket where the heavier gauge red and violet wires plug in, make sure that the car is in park if auto, or neutral if manual because doing this bypasses those interlocks, if the car cranks then the TDR is not being energized, if it does not crank then your problem will be the starter solenoid.