I have an 85' Grand Prix LG4 and have a stupid electrical issue I hope someone can help with.
I've been having fluctuating power to the headlights that goes out momentarily when I hit a hard bump.
Everything is tight (been all over it, wiggled everything I could lay my hands on including the starter)
I got into it this morning and turned on the headlights and the dome light came on ????? After a few in and outs, the headlights finally came on (without the dome light). No I didn't turn it when I pulled.
Now on every little bump the SES comes on and the Headlights go out for about 1/2 second.
Could I have a short to ground in the headlamp switch that could cause that much of a voltage drop without blowing a fuse?
Any other cause you could think of?

 

Update:
After miserably failing emmisions testing, on the way home the SES light began flasshing a rapid 2 pulse on/off with the car attempting to stall each time the flashing started (about 2 seconds then repeat) The dome light was dimly flashing with the SES light. Headlight switch did not operate headlights but turned on the dome light brightly.
I finally struggled it home and in the driveway my son opened the passenger door, the SES went on solid and the car began to run better. Holding the door switch inward to break the connection, The SES would begin the two second, 2 pulse cycling again.
Car is basically losing power from this but is not blowing fuses.
I pulled every fuse trying to isolate this but its not following any pattern.
Its not the headlight switch or any headlight grounds.
Unplugged every light AND unplugged the headlight switch with the same results. Wires on the starter confimed tight and making good contact again just to be sure.
Anybody got any wild ideas? (I'll take anything at this point)

 

As I see it, there are but two options:

1. Take your son with you everywhere you go, and instruct him to hold the door open as you drive. This could have several negative implications, however, especially in inclement weather, or if you value your son's welfare, or if the laws of your area prevent you from driving with the doors open.

2. Isolate and repair the grounding problem that is causing the trouble. I'd start with the ground strap from the engine to chassis, then chassis to I/P and ECM, but don't overlook any of the grounds.

 

I think I found it but need to look further.
The two fusible link wires that run from the starter go thru a steel tube to protect them and I belive they are either melted to gether or cutinng just lightly on the edge.
I pulled them out about an inch and the problem "seems" to have gone away.
Went for a quick drive (see below) and I think its running OK.
I'll pull the started tomorrow night and do the rewire if needed.