Hey All,

Just noticed the other morning, that I've got something different going on with my headlights. Up until then, things had been working as they always had. DRL's with the high beam bulbs at reduced power. Low beam headlights from outer bulbs each side, high beams turned low beams off and ran inner bulbs at full power.

So what I have now, is basically the quad headlight setup, but I am getting reduced power to the Driver side low beam. Making me think that I have a short somewhere.

Could this possibly be due to the multifunction switch on the steering column? I've had issue with that for a while, where it makes the Turn Signal Relay click on-and-off repeatedly. Have even had small amounts of smoke from the steering column with the turn signal on. I am really hoping that replacing the multifunction switch might be able to solve both of these issues. However, the headlight thing is a recent development, and I'm a little worried that it might be un-related.

The reason I think that, is that I have recently swapped to Halogen projector headlights, and I have concern that maybe there is an internal wiring issue with that entire assembly. Again, that was working properly up until I noticed this issue the other morning. Also, A while back I had a remote start kit installed (by professionals, not a DIY). I believe that was set to turn the regular headlights on when started remotely, and then with key insert, and turn to run, it would switch over to DRL. So I suppose there could be something In that wiring also that could be crossed up.

Ideas on where to start? Would love to hear your thoughts. Thanks!!

 

I'd first check the relays for the headlights. Does the swap to halogens draw more power? If so, the added current could have made a slightly corroded terminal that was fine for low current, over heat and go bad.

In an attempt to understand the circuit for our headlights and create an over ride for the DRL, I created a circuit diagram pieced together from several pages from my service manual. I'm including here in case it helps. Looking at the diagram, I do think that a problem with the multi-function switch could be a source of your issues.

 

Awesome, thanks for compiling and sharing that diagram.

I don't believe that the projector halogens draw any more or less than the OE halogens, but it uses an H-1 in a aftermarket housing instead of the usual 900-whatever low beam is. But relay is a good idea, I had not considered that.

I should add that my DRL are functioning correctly. All goes off the rails when headlights come on, I get the nearly-quad look. High beams only illuminates the Pass Side to full brightness. Low beams stay on when set to High via multifunction switch. Headlight switch dial seems to do what it is supposed to, from "off, parking, on".

I was going to swap the OE light cluster back in just to see if they behave the same way, I will try and get to that over the weekend if it isn't too cold/snowy to be out there working on the truck.

I have an HID projector conversion waiting on the workbench, but won't be considering putting that in until I resolve this issue.

I started to look at multifunction switch replacement a while ago when I first had the turn signal relay constantly clicking. But I got spooked by the cautions about the air bag deployment and all that, I will probably entrust my local shop to that job when the time comes.

 

You are very welcome. Hope it helps. Note that the diagram is more of a logic one and the actual connections and routing are not always well represented.

As for the airbag stuff, it can be done safely at home. I had to do it to get at my remote radio controls to fix the lights in them. If you have access to the official GM service manual instructions for disabling the airbags (SRS) then there is no reason you can not do it yourself. I have the instructions for my 1999 but I don't know how similar they are to yours.

Good Luck!

 

I had my local shop swap in a new multi-function switch. Did not have any effect on the current headlight situation, but it did solve my incessant turn signal relay clicking at least.

Next up will be checking/replacing the headlight relays and main switch can follow if needed. I can tackle those jobs as time allows.

 

UPDATE: Still fighting this one. Curious if anyone knows where the headlight wiring is grounded? Do the harnesses all share a ground via the HDLP GND relay? That is what it looks like to me based on the wiring diagram. Looking to confirm. Thanks!!

 

Been thru all relays under the hood, and multi-function switch replaced, headlight switch replaced, still no resolution. Leads me to a wiring issue probably on the ground side I'm guessing. I'm probably done chasing this, and will enlist a shop to take it on.