Update: I decided to screw going through all of the wiring harness on the cars front end lighting harness and just reground the drivers side high beam with a 12ga ground wire bolted the the A/C radiato bracket bolt.- Its cleanly hidden away and i left the lights on for 25 mins and the ground never got warm and the continutiy was great on it. So that fixes that for now, maybe later I'll take it to the stealership and they can charge me $70 an hour to fix it but for now its good enough! Thanks for all the input guys! by the way if anyone needs TSBs and stuff for the newer gen bonneville Alldata has a 2003 SLE as one of there tryout vehicle (unlimited use). Thanks again!


Ok, I'm in a bit of a panic here, I just (about 2 hrs ago) hand washed the ol' bonne. Did a fine job i might add. But anyways, I pulled her into the garage and the twilight sentenial kicked the lights on, I just bought a new fog light bulb so i also kicked the fog lights on and turned the lights on manually, I shut the car off, got out and looked at the fogs, then opened the door and turned on the brights, only the passenger one is turning on. Hmm...
So i pulled the headlamp assembly and took a look at the High Beam Bulb (which is fairly new) It looks fine! so i grab the trusty digital multimeter, I figured out the the two top pins are for the positive low/high current and theres one smaller pin in the middle that is the primary ground. I checked the both on high and low, obviously the Lows put out 12V (around 11.9 with engine off) but the High beam pinout only puts out .06 V at the most, I am kinda pissed off because this is a newer car and shouldn't be having electrical issues so soon. Any help would be much appreciated. Thank You!

sounds like headlight switch, but I am no expert

Its a possiblility but I have NEVER heard of a 2000+ switch go bad, plus the other side works fine! Keep the suggestions coming in. thanks, I was thinking maybe some of the water got into someting in the wiring, I'll let it dry out a bit. Thanks

check your fuses. there are seperate fuses for the right/left high beams. Do your DRL'* turn on? If you unlock the car at night (and it'* dark around the car) do the perimeter lights turn on, including the high beams?

I checked the fuses, the DRL'* are bypassed on our bonneville, checked the bypass wire, its fine. We also have an Avital Remote Start so I guess I could check it but I'd have to get out the factory key fobs. Hmmm. I hoping its not but thismight be a wiring issue between the Electrical Buss Panel and the Headlamp itself. I hope not! Thanks!

You could remove the fuse for the left high beam (fuse #10) underhood fuse block. Check for the + 12vdc on supply side of fuse socket, then do a continuity check from the load side of fuse socket to the apropriate pin in the left head light assembly wiring harness for the left high beam. Maybe you're losing power somewhere between those two poiints. When you disabled the DRL'* I'm assuming the DRL relay has been removed, and a jumper placed between terms 30 & 87a. This jumper maintains the ground for the left high beam in the absence of the DRL relay.

I jumped the DRL pins accordingly, so when i get a chance I'll take a look at the car, its not here right now so. Thanks!

OK... I pulled the light assembly again. I screwed around with the pinouts again and figured out which are which. It seems that the Drivers Side High Beam is getting 12V + but it has NO ground!? Which is really weird. Does anyone have access to the Wiring Diagram for the 2000+ Bonnevilles. I need to find out where the ground "terminates" on the harness and see if its bad. But the only thing i am wondering is that aren't both headlamps ground in one spot?! Further info would be much appreciated. Thanks! Also the Blinker went on the fritz, the driver side front blinker indicator was blinking fast indicating a burnt bulb, bought a new bulb, the old one is OK, put the new one in, same issue, tested some stuff, put the bulb back in, and the problems gone?!! :?

The grounded side of the high beams are in two different locations. The left hb ground location is G103. The right hb ground location is G401. G103 is located just forward of fill cap for windshield washer fluid. C108 connector pin A is power (12v +) to left hb, C108 pin B is ground for left hb. You should read continuity from pin B to ground through the jumper installed in DRL relay socket. Double check the jumper. The jumper takes the place of the normally closed contact of the DRL relay.