Has OP gone again ? Seems to me, that "Remote Start / Alarm" coupled with modified wiring is probably the issue. Maybe start with checking ALL the points where the aftermarket bodges were connected, and re-instate the LR wiring. Then 12V, GND & Signals might get where they are supposed to be.

There were a bunch of "remote start" posts on rr.net a while back, and most of them involved quite a bit of modifying stuff that worked perfectly ok before !!
 

Similar threads