Headlights malfunctioning

rudyb · October 19, 2014

Well, I screwed up my headlights and I can't quite figure out how to fix it. I have a 2000 half ton silverado lt 4wd. Several years ago, I added a relay on the radiator support for the quad headlight mod. If you are unfamiliar with this, it keeps your low beams on when you turn the high beams on. It worked great until Friday night. On Friday, I received some additional led flood lights in the mail. I was pretty excited, so I wanted to install them and test them out. What I wanted to do is have a small toggle switch in the cab, run a wire from the switch to a relay, and hook them up the proper way. One problem: I didn't have a spare relay sitting around. Solution, I'll just hook them up to the relay that I installed for the headlight mod. Not a great idea. I started probing around with my digital multimeter. It fell off of the bumper onto the concrete and broke. I continued screwing around with my analog multimeter. I knew where each wire went, and what they did, but I couldn't get the right combination down. I was in a hurry and wasn't thinking straight. I read that if I messed up the relay, the lights should go back to normal functionality. So, I screwed around way too long until I finally broke something.

Final result: when I turn on the lights to low beam, both low beam and high beam on the driver's side come on, but they are both extremely dim. I'd guess they aren't even 25% of the original brightness. The passenger side works fine though. When I switch to high beam, same thing and passenger side still works as expected. My initial thought was, okay I ruined the relay. I unhooked the relay, no change. There is a relay in the fuse box for the headlights and another for daytime running lights, maybe I messed the headlight one up. I swapped those two, no change.

I think at this point I was pissed off enough that I went in the house and sat on the couch. The next day I came outside and turned my lights on as I brainstormed and now the high beam on the passenger side is in the same condition as the driver side: on all the time and 25% brightness. For some reason the passenger low beam still works.

I've been busy harvesting soy beans so I haven't had a chance to do anymore troubleshooting. If anyone has any ideas or input, I'd like to hear it. There are currently three things I can think of that could be damaged: the BCM, turn signal switch (as it controls lo/hi beam), and the switch that actually turns the lights on. My mother has a 2001 suburban ls 4wd. I'm thinking about robbing her BCM and headlight switch and testing it in mine. Any thoughts on this?

kstruckcountry · October 20, 2014

I would start by returning it to 100% stock and then see what happens (undo the 4hi mod). Then if it works add components back and see which one screws it up...

Side note: how are the beans? Many of the full season beans here got burned, but the mid and short season look to be ok. May go to work next weekend and play with the new 36 foot flex draper

rudyb · October 20, 2014

I didn't explain very well, but it's back to stock with the current problems. I'm home now, and I've learned that unhooking the bulbs on the driver side fixes the issue on the passenger side which is strange. Almost leads me to believe that the high beam bulb on the driver side is bad. I'm going to be out here troubleshooting for a bit and I'll post my discoveries.

We just started cutting Saturday. I know how many bushels came off of the first field but I'm not sure exactly how many acres are there. Rough estimate is 32 bu/ac. We store most of our own grain so we haven't taken any samples in yet. The field we are on now is 1/3, and 2/3 split so we'll be taking some grain to the coop tomorrow. So far the beans have been kinda small, and don't seem to be very heavy. Moisture is about right. I haven't seen hardly any of them cracking. Idk what you guys yield up there but we're not complaining about 32bu/ac. We've raised better, but we've raised worse too. These didn't burn up, but they really needed a couple more rains. The plants we're cutting now are almost waste height and about the top 1/3 of the pods didn't finish filling. Anyway, I'm going to get back to work. I fixed my multimeter a few minutes ago. Maybe I will have some more good luck.

rudyb · October 20, 2014

Wow. The problem was a tiny 15 amp fuse. If you check the picture, you will see a 15A fuse labeled "LT HDLP". That was all and sometimes I am kinda dumb. Anyway, I'm glad that's all it was. I learned my lesson.