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NEED A LIGHT SWITCH , HEAD/PARK/DASH-DIMMER ALL IN ONE ,WILL ALMOST ANYONE DUE THAT IS CLOSELY RELATED OR IS SOMETHING DIFFERANT ABOUT IT , THIS IS A 12volt system.

The military switch will work on a 12 or 24 volt system.

may be same problem with the switch / when the head lights work and I would push the bright lights switch one light goes to high then the other stays the same got two new beams and still the same deal , what to look for, GREMLINS OR LITTLE GREEN MEN WITH NIBBS HELMETS ON .

CHARLES THIS SWITCH IS OR LOOKS TO BE A REGULAR TYPE AUTO SWITCH IT IS NOT THE SWITCH THAT IS ALL IN ONE AS I've SEEN ON MOST PICTURES DOES IT MAKE A DIFFERENCE

anthony manzella wrote:may be same problem with the switch / when the head lights work and I would push the bright lights switch one light goes to high then the other stays the same got two new beams and still the same deal , what to look for, GREMLINS OR LITTLE GREEN MEN WITH NIBBS HELMETS ON .

This problem would be either the dimmer switch or wiring. From what you have described, my first thought is wiring. From the dash mounted switch to the dimmer switch is only a power lead. Power going to the actual high & low beam functions would be between the dimmer switch & the sealed beams. There should be a lead from the dimmer switch to the low beam side, a separate wire from the dimmer switch to the high beam side. Ground is OK or you would have no lights at all. Depending on how it is wired, it could be 1 wire for low beam with a splice tieing both sealed beams together, the same for the high beam side. It could also have 4 separate wires with no splices used. Really it sounds to me like someone may have used the splice method & got some leads crossed in doing so. This type problem must be traced a wire at a time, shouldn't be that hard to locate the issue. Could also be the dimmer swich has some bad internal contacts causing the cross up from within.

anthony manzella wrote:CHARLES THIS SWITCH IS OR LOOKS TO BE A REGULAR TYPE AUTO SWITCH IT IS NOT THE SWITCH THAT IS ALL IN ONE AS I've SEEN ON MOST PICTURES DOES IT MAKE A DIFFERENCE

When you have non-original parts in place, there is no telling what someone has rigged or how they did it, I've been amazed may times at things I've seen, keep this in mind; however if the change was done in a typical manner, the type of switch they used shouldn't matter.

THANK YOU CHARELS FOR BEING SO QUICK EVEN ON THE 4th of JULY GOT TO GIVE UP A BIG SALUTE !

Check the grounds on the head lights. You might have an issue there. I have found that 90% of wiring problems on Military vehicles is a bad or poor ground.

k8icu wrote:Check the grounds on the head lights. You might have an issue there. I have found that 90% of wiring problems on Military vehicles is a bad or poor ground.

Ground would not be the problem in this case, each sealed beam has its own ground source. If it were a bad ground, the light would either be noticeably dimmed or not work at all. If the low beam is working normal, the ground has to be good, no need in wasting time chasing a ground this time. Of course this is based on my understanding from the description of the problem.

Well...I'm no expert I mean I've only been playing with military vehicles for 25 years so I still have a lot to learn, but I have seen were poor grounds will do things like low beans work good, but then highs don't....Besides if he cleans up the grounds what will it hurt?

WELL LET ME TELL YOU WHAT I FOUND OUT ! the post for the head lights was broken from the switch it's self the damm switch is from a G M THANK GOD IT WAS MADE IN U.S.A. so I drug my butt down to my trusty old time auto parts store and got it cross refferance and order the same switch for now so I CAN HAVE LIGHTS! but have not figgerd out the bright light problem need to wait for the new switch , CHARLES YOU ARE CORECT SOME PEOPLE WORKING ON THESE TRUCKS SHOULD BE HUNG BY THE SHORT HAIRS ! sure makes you wounder ! THANK YOU ONCE AGAIN !

k8icu wrote:Well...I'm no expert I mean I've only been playing with military vehicles for 25 years so I still have a lot to learn, but I have seen were poor grounds will do things like low beans work good, but then highs don't....Besides if he cleans up the grounds what will it hurt?

Cleaning the grounds won't hurt at all, I'm simply stating that in this situation if ground turns out to be the cause, I'd be surprised, but hey, stranger things have happened. Didn't mean to offend anyone here. So I find myself trying to explain my explanation once again. I too agree ground issues cause wierd things sometimes, I also know the 3rd lead on sealed beams is the common ground for that element. If ground is bad, both the high & low beam of that element is affected as they have the same common ground. This being said along with the other information he shared in previous post, in my opinion "ground" isn't the issue simply because he said his low beam was normal. I shared my opinion based on the information he shared & on my many years of working with M series trucks in general. If it were to turn out that my theory was not correct this time, so be it. We are all limited on exact information here on the forum when attempting to be a help with someone's problem. Not having exact information has a serious effect on the answers people need at times. This is why you may have noticed that in more of my replies, I simply tell people to call the shop if I can help. That way I can get a full explanation of the issue, I can ask the questions I need to ask, thus making a much better jab at solving the real problem. As a result of asking people to call, I've been asked by moderators on some forums not to do that but to answer people's questions on the forum so all can read & benefit. I understand where they are coming from & agree fully that all can benefit from issues others have. I've responded to them just as I have here in telling them that people come up offended & that is the reason I just ask folks to call. One gets offended, which leads to another getting offended & so on. I'm very busy with years of work on the books, I wonder why I bother, I've also noticed that others in this business like I am simply don't bother. However I feel an obligation to help people, I guess it's just my nature & the way I was raised. I'll continue to help when I can, to anyone who would rather call me at the shop, feel free, I've always taken the time to talk to people & really enjoy doing so. Again I apologize that I offended you.

I agree with you Charles. If two circuits share the same ground and one is functioning correctly and the other is not than the ground most likely is not the root cause. I would have to say the issue is with the wire connection where it splits from left to right. Most likely loose or broken contact.

Ground could still be a problem. Here is why. If the ground is only partial and the low beams work the ground may not be giving enough resistance at that wattage level, but when the high beams come one which are a higher wattage filliment the resistance in the poor ground connection is enough that the lights don't work or the voltage feeds back and you get one working and one not. I know you might think I'm nuts, but I've seen this and stranger things all because of poor or weak ground.

I'm with Charles on this one. The fact that one headlight goes from low beam to high beam okay while the other stays on low beam is an indication that the one that doesn't work right is wired incorrectly. If it were a case of a burned-out high beam filament, the light would just go out when the dimmer switch is activated. He'd have high beams on one side and nothing on the other.

While it's possible for a ground issue such as you describe to exist, he would probably have a noticeable flickering of the headlights when driving over even slightly rough terrain (like our pot-holed roads).