This is the module.
I知 building a new dash harness for my 455 Olds powered 81 GMC 1/2 pickup. In addition to installing a factory tach, I知 adding Retained Accessory Power, and the fancy dimming interior lights that many late model cars have.

A couple of winters ago, my son and I installed factory power windows, mirrors, and door locks on his 92 Yukon. In anticipation of that project, I stripped several wiring harnesses out of many later model trucks. I find it痴 much easier to lay out the harness, and diagnose problems later when the wire colors match up to the factory colors. Old harnesses contain all the oddball wire colors, and in the correct wire gauge sizes.

For the RAP and interior dimming, I知 using modules from The Timer Shop. Which brings me to my point.

While stripping some harnesses of the friction tape, one of the dash harness has a module with the part # 15956514. When I googled that number, it痴 identified as Interior Lamp module. I知 curious if that module will do exactly what I知 hoping to accomplish with the aftermarket stuff. Unfortunately, I知 not sophisticated enough with GM part numbers to figure out what exactly the module came from to be able to find a wiring diagram.