M52A1 weird headlight problems

[jamboly]

The headlights on my M52A1 are acting weird. In different switch positions the left or right headlight will be either bright or dim. Below is results with different switch positions.
Panel light switch in off positon;
Service- right headlight bright, left headlight dim
Stop and off positions- not lights
BO marker- headlights off, right BO marker on
BO drive- right headlight dim (come on slowly), left headlight bright, right BO marker on, left off.
Panel light switch in park postion
Service- parking lights only, no headlights
Stop and off- no lights
BO marker- right BO marker only
BO drive- left headlight bright, right dim, right BO marker on.
As far as the low beam high beam switch, it works on the bright light only, regardless of panel light lever position.

I am guessing that the left BO marker bulb may just be bad and have nothing to do with the healight probem.

So, what could be causing one of the headlights to be dim and then switch as to which one is dim, depending on the switch positions, and why are the headlights on in BO drive? I have ruled out the switch, since it only has one output for the headlights. An Olive drab posting on the light switch pinout mentions something about a headlight relay for pin H, but I can't find anything about a headlight relay in any of the manuals. I am also lost as to what type of wire short would create this problem.

Anyone want to take a stab at this?

 

[Prince]

Sounds confusing - however I would tackle the known problem first.

If I understand your terminology, when you mention "low beam high beam switch", I assume you are talking about the "dimmer switch" mounted on the floor board which is activated by your left foot.

That switch should transfer power to the low beam headlight filaments and then when the switch is activated, will transfer power to the high beam headlight filaments as well as the high beam indicator in the instrument cluster. If it does not, then you already have a fault tree box that needs to be eliminated. Just my 2 cents worth of thought.

 

[jamboly]

I was talking about the dimmer switch. However, your question made me realize an error in the wording I used in the posting. When I say that one light is bright and the other is dimm, I should have said that one headlight has a "normal" brightness and the other has a dim orange glow (like not getting enough voltage). The problem is not associated with the low and high beam elements of the bulbs.

 

[vtdeucedriver]

Ok quick check. Look at the back of your headlight buckets. on the back if there is not too much paint, the wire #'s are stamped on the back of the bucket. Make note of your wire tags on which wires are going to what at the headlight. I kind of wonder if your black out drive light on the left side is wired to the left headlight.

Check your wiring at the lights and then quick, thought to throw a light switch at it and see what happens.

 

[vtdeucedriver]

Ok I read it again, this would not explain the right head light to also get power enought to attempt to light up. I would still verify your wiring to the head lights before anything and then have devin take out the switch of the deuce and put it in and see if you have a problem

 

[73m819]

SOME bad GROUNDS, the dim is a classic sign, the current is comming BACK though the other light instead to ground

 

[jamboly]

Jeff; We double checked the wires to the headlight when we recently had the radiator fixed. As you stated, that would not explain the lights from both seeming to work correctly, depending on the switch position. I would buy that if the other lights were also acting weird. Since there is only one output from the switch for the headlights, I don't see how that could be the problem. I think 73M819 has the right idea. Whenever I have run in to weird lighting problems on some trailer I have, it always seems to be corrected by fixing a ground somewhere. I think I will look at the grounding, but I am not sure where to start.

 

[vtdeucedriver]

I will look at mine in the am to see where the main harness ground is located. I know my typical problem has been the turn signal flasher ground. Ever since the govt went to the solid state flasher unit that is plastic, I've had problems. I have helped some of it by running another ground wire to the main ground wire from the flasher unit ground wire.

 

[jamboly]

I cleaned up and checked the ground wire on the flasher module on the firewall. No change. The problem ended up being the ground wire to the left headlight. The ground wire went in to the wire harness that goes up under the dash and I couldn't figure out where it went to ground. I made up another wire that went from the headlight ground to the ground screw on the fender where the alternator is grounded. "Everything" works right now.
I said eveything works right now, but I did create another mistery for myself. In the process of going through and checking all the positions on the light switch I noticed something that did not match my documentation. I was using the diagram for the M151A2 that shows which lights come on in the various switch positions. The diagram shows that the front yellow running/parking lights are on when the switch is in the Service Drive position. They didn't come on in that position on the M52. I checked the M35A2 and M936A2 as well as a couple of M35A2s at the museum and they didn't come on in the Service Drive position either. I figured it was a documentation error. I checked the M151A2....and they come on in that position. How can that be if they all use the same switch? I know there are several part numbers for the switch, but I thought they were all the same.

 

[vtdeucedriver]

Look away Jim just look away I dont know if you have gotten Devin out of that Mack long enough to check things out on Facebook since he turned 16 but let him know about my new ride. 1967 M54A1..........

 

[jamboly]

He already told me about it. How long is going to stay yellow.