Hey guys, new guy here with a 2001 Bonneville SE (Bought New in 01) and is completely stock. I've never had any big problems with the car except for the LIM-gasket failure which I did around 40K miles with the metal gasket and updated UIM, has 101K on it right now.

Yesterday it poured rain and was very windy(If maybe that helps) and I drove in the storm and everything was working fine.

Went out this morning to go to work (Early, about 5am) and it was still dark. Started the car, dash lights came on, tail lights came on but the low-beam headlights stayed off. I couldn't even get them to come on via the manual switch. Fogs work, high-beams work and all other lights.

The auto-light sensor seems to be working as it'* "clicking" the lights on/off but the low-beam headlights stay out, like I said, even with the switch. The odd thing, when I use the remote to lock/unlock the doors, the low-beam head lights flash a couple times as usual showing me that at least the bulbs are working.

I've checked as many of the headlight, DRL, etc fuses as I could find and none appear burnt or broken.

Any ideas on where to look or where to check for power with a multimeter?

Thanks for any help!

-Just thought I'd add that I swapped around some relays to see what effect I might get and nothing changed. I swapped the DRL relay and high/low-beam relay and still no low beams.

No hints huh? I usually don't get home until 4 and by then, not much daylight left. I'm sure I'll figure it out this weekend. I'll have to check the grounds and possibly the switch on the column?

Any wiring diagrams relating to the headlights, auto-lights, DRL, etc would be great if anyone has them.

Thanks again

I'm going to take a stab at this. Usually when something works under one condition (use remote, lights work) but not under other conditions (headlight switch), I suspect a bad ground.

Did you check the ground bus by the driver'* door? That would be the first place I'd look, and there is a tech article on this board on how to check the ground bus.

I haven't checked the ground bus by the driver'* door and I am very glad you said so. Some time ago, the plastic/rubber sheeting under the door panel un-stuck itself and started to leak. Twice I had a large puddle in the driver'* foot well. I pulled the carpet up, dried it all off with a hair dryer and resealed the door and it'* been dry ever since - but I'm sure I'm going to find a blue/green ground bus when I pull the trim/carpet again.

Thanks!

I just wanted to add to this in case anyone else any ideas.

I checked the ground buses I found in the engine bay, the two on either side of the front doors (They're located on the door pillar by the brake lever, not on the floor so they never even got wet) and one near the battery under the back seat and absolutely none of them showed ANY signs of corrosion. They're clean as a whistle, I was surprised but I did fix the water leak and dry it ASAP.

So as it stands, the low-beams do not work when needed. They only flash when the remote is used. I have been using fogs/brights to drive at night. Also, the DRLs are non-functional. Once in a while, I spot the DRLs running when I'm close to another car but that'* it - only once in a while.

I guess I'm going to have to get a repair manual for this car and take a good hard look at the electrical system which I'm not looking forward to at all because there'* just so much electronics in these cars.

To make matters worse, after reconnecting the battery after inspecting the ground buses, The SES light came on. After looking around the engine compartment, I found a bad UIM leak around the throttle body side and the front-facing side of the UIM. The "updated" UIM only lasted 61K!!! Damn it. It'* seeping pretty badly but wasn't when I played with the lights about a week ago, so this just started.

So thar she sits, until this weekend when I try another "updated" UIM or maybe a metal one from an earlier model 3800 if it fits. That'* not a problem - but these lights! :(

If you really want to get your lights working I would make a relay harness to hook into the stock bulbs, maybe you can modify an HID relay harness and run a switch temporarily to have the low beams work when you turn on the switch, except it will be manually all the time so you could accidentaly leave it on, if you want to look into this I could check out getting a harness put together from parts I have around and either send you the parts or make it for you