A2 - AUTO TRANS 12V. IGN - NOT NEEDED
B2 & B3 - NOT USED 3500HD
C2 - PARK/NEUTRAL SAFETY SWITCH - NOT NEEDED
D1 - ABS DIAGS GOES TO DLC - 3500HD ONLY
Are there terms on the firewall conn. for any of the above terms?
That metal box is the speaker amp.
The receiver is a black plastic box on the other side of the metal bracket that the amp is mounted to.
The photo I posted with an arrow is one of your photos. 3rd photo post #4.
It's there or your keyless would not work.
First of all, if the other door locks...
The ORANGE wire tells the GPR that the GLOW PLUGS are actually getting voltage and to start it's program.
The BLUE wire sends 12v. to the WTS lamp when the glows are glowing.
You can add a ring terminal to those and put it on the GPR stud.