01 pontiac boneville dome light issues

I am having some issues with the dome light. I found the wire at the underdash light as a gray wire and (-) trigger. The wire tested fine showing 12 volts with doors closed and nearly zero with the doors open, the interior light turning off and on as I closed and opened the doors.  I finished the alarm install (lock wires were a pain!) and tested the alarm to make sure it was functional. Shock sensor was good and door trigger worked. However when I started the car and backed out of the install bay, the dome lights dont come on any more when I open the doors. I undid the solder to the underdash light and after awhile the lights came back on while i was cycling the ignition. I wired it back up and everythings works fine until I back it up again. Anyone have any clues or tips?

oh alarm is an Ungo S100

1. Why not just use a module? For around $40 or so, something like the XK01 would have given you locks, trunk, and door trigger, without going into the doors. 2. All of those 2000+ fullsize GM FWD cars, the domelight doesn't come on during daylight. Bonneville, LeSabre, Deville, they're all the same. Put the car somewhere dark and it will probably work again. 3. Because of #2, keep in mind that your alarm won't trigger if someone breaks in during the daytime. If you need the door trigger to work both in the daytime and nighttime, you could run a wire into each door and get each door trigger inside the door, or buy a databus module.

well I wired the instant trigger to the underdash light (blue one) and it appears to have fixed it. The dome light comes on normally with the door opening and closing and the customer hasnt returned nor called about the issue for nearly two days now. Funny thing is my other installer came across a similar issue except on his the domelight still functions normally but for some reason when wired to the green door trigger wire, the alarm doesnt detect the door opening even though with a DMM it shows + 12v's then ground when door is opened. So he wired it to instant and now it works fine.