Hi Beam issue

While driving home today, I nicely found out that my high beams sometimes don't work lol.

This is a Canadian truck, so it has daytime running lights, which run 6V to the high beam lights when the headlights are off.

What happened is I left town, went to turn my high beams on, and my daytime running lights came on, went back to low beam, they worked fine, back to high beam, and they worked fine. Tried this a few times, and if I turn my light switch from headlight to park light, and back to headlights, the high beams turned on (with the stalk in the high beam mode all the time). After it did this a few times, it never did it again. Is there a common-ish issue I should look for, maybe a bad switch, or connector, etc...

I am not sure how the daytime running lights is wired up, but I think a relay switches the DRL on, and maybe that was happening. Before I start searching, I thought I would ask if there is a common problem, you kinda crap your self a little when your headlights turn off when it is pitch black outside, doing 70MPH down the highway lol. My guess is an iffy switch for the headlights, and it turns the headlights off when I switch it to high beams, the truck has 300,000+KM on it.

The headlight switch part of the combination switch in these trucks do go bad over the decades. But Axel Breaker has written a fix how-to
See
and

Definitely sounds like a bad combo/headlight switch. The controller and the relay only come into play when the headlights are OFF. As soon as you turn the headlights on (hi or low beam), the controller should sense that and turn the DRL OFF. So it didn't sense your headlights were on because of the bad switch and that's why it turned the DRL on. The controller (which is built into your ABS computer) senses the power coming OUT of the headlight switch. So if the switch is bad, the DRL computer doesn't know it and just assumes the headlights are off and therefore turn the DRL on.

In short, when you turn the headlights on hi or low, you should get power to the headlights just like any other truck.... and that means that neither the relay nor the controller is involved. It's relay & controller failsafe. If you had a problem with either one of those, the hi and low should function normal.

This is what I figured was happening, since the DRL's came on. I have not used high beams very often these last 2 years, up here in the summer its sunny from 5AM untill as late as 10:30PM in June lol. Right now its only sunny until about 8:30PM. In the winter, its the opposite, it is pitch black by 5PM, and the sun does not come up until 9AM in December, and I never see sun on days I work lol, so headlights are always on. I had my switch and everything out last winter when I rebuilt my truck, but I didnt touch it as everything worked, and nothing looked melted, but looks like I will be pulling it out and rebuilding it.

Let us know what you find.

Also, as long you have that combo switch out, you can clean the points up on the wiper switch just the same. There are a few pics here.... starting at post 15.

!