HEADLIGHT PROBLEM

[Bloo]

5 hours ago, LAS VEGAS DAVE said:

If i had the wire on terminal 9 like it shows in the shop manual leading to the fender terminal block everything would work----- I THINK.

 

There has to be a bit more to it. The 1938 wiring diagram shows a straight run of wire from terminal 9 to the left low beam, with no splices or junctions, and no other wires connected to the left low beam at the headlight.

 

There must be something connected to the low beam at the headlight end because your system works on position 3. This begs the question: There is a wire connected to the left low beam, it has to be connected to something at the other end. If it isn't connected to pin 9, what on earth is it connected to?

[Ben Bruce aka First Born]

I know what I would do!  Get a '50.

  Seriously, unless one REALLY wants the method  the '37-'38 has, wire it like the '50. Determine a terminal/position on the switch you want to use. Forget the rest. From said terminal to input on floor dimmer. One wire from dimmer to one head light on the fender high beam. One to low beam. Connect left high to right high. Same for low.  No one will know, even if showing. Simplifies everything. Buick must have thought so as well, since THAT system did not last.

 

  Ben

[MCHinson]

Dave,

 

You have reported several different wiring configurations in several different posts. Please post a photo of the switch so we can all see what you have. It is impossible to help you figure out what is wrong if we can't understand how the switch is actually wired.

[LAS VEGAS DAVE]

Here is my switch picture and fender board picture. There should be a wire from the terminal in the switch with the wire tie in it to the fender board. Notice on the fender there are two wires on the front terminal which is fender lights and only one wire on the rear of the fender board which should have two. It is the wire from the switch that is missing. I see no sign of it coming from the loom under the dash or under the hood. To test my theory I hooked up a wire from the empty terminal with the wire tie in it to the fender board where the 38 shop manual shows two wires and the complete lighting system worked perfectly. I don't know if when TNZ made the loom it was left out or if the mechanic that installed the new loom cut it off or whatever but the bottom line is there is now only two ways to fix it and I don't want to do either one. Number one is to replace the loom and number two is to run a wire outside of the loom. I think my number 4 position will always have a low beam that will go completely out on the drivers side if the dimmer is placed in the low beam position. I will still have a normal high and low beam in the number 3 position. 

 

Edited November 24, 2017 by LAS VEGAS DAVE (see edit history)

[MCHinson]

Dave,

 

You have posted multiple descriptions of your headlight switch wiring so I still have no idea what the wiring looks like. I certainly can't see which wires are attached to the switch in that photo. If you post a photo showing the wire connections to the headlight switch, I am more than happy to try to help you figure it out. Without a photo that shows the wire connections, I really can't help you with it.

[MCHinson]

Since several people seem to be having problems with headlights recently, I decided to do some research on the subject today. I disasssembled, cleaned, and tested the headlight switch of my 1938 Century project today. The pdf attachment shows the results of my analysis of the switch today. I am amused and amazed at how they designed that switch. It is too confusing to easily understand how all of the connections are made internally. It appears that there are a lot of different ways for current to flow during the normal operation of that switch. Perhaps it was designed to have redundant feeds to reduce failures. That redundancy also makes it difficult to easily troubleshoot a problem, because of the multiple connections that are occuring at the same time.

 

I have not yet done anything with the dimmer switch. It also plays a part in the operation as other connections are made through the wires connected to the dimmer switch. I think when I get around to checking out the dimmer switch, it will be possible to make a better chart that includes the dimmer circuits as well. Until I do that, I still won't have a complete understanding about all of the potential failure modes that could be causing issues such as Dave's.

 

I am also attaching a before and after view of the internal switch contents. It just needed a little cleaning to make the contacts look good. 

1938 Buick Headlight Switch.pdf

[LAS VEGAS DAVE]

46 minutes ago, MCHinson said:

Dave,

 

You have posted multiple descriptions of your headlight switch wiring so I still have no idea what the wiring looks like. I certainly can't see which wires are attached to the switch in that photo. If you post a photo showing the wire connections to the headlight switch, I am more than happy to try to help you figure it out. Without a photo that shows the wire connections, I really can't help you with it.

 

I have done all I can with the pictures. The important thing that you seem to miss is there is a terminal that should have a wire in it that does not and is shown by the wire tie that is in it.  I know what is wrong and I proved it as my post above explains. It is not the

 switch that is the problem. Thanks for your replies. 

Edited November 25, 2017 by LAS VEGAS DAVE (see edit history)

[Bloo]

MCHinson: If I could give your last post more than one thumbs up, I would.

 

Yes, they went through an unbelievable amount of machinations in that switch. From the circuit diagram I knew that had to be so, because the dimmer switch is wired to one headlight. The high/low on position 3 means the current needs to flow in and out of the switch in some strange way for the OTHER side to beam down.

 

It doesn't really surprise me. On my 1936 Pontiac Multibeam system (uses the same lenses as a 1936 Buick), there are 2 fuses. One is for almost everything in the car that is fused, and the second is for one headlight. They did similar voodoo with the headlight switch to keep that one bulb connected to the the second fuse (by itself) no matter which filament was in use. I assume this was so that either fuse could blow, and you would still have a headlight on. That was kind of nice of them. I see they abandoned that idea when they went to the thermal circuit breaker for 1937-1939.

 

The dimmer switch has to be normal... doesn't it? There are only 3 connections.

[MCHinson]

11 minutes ago, LAS VEGAS DAVE said:

there is a terminal that should have a wire in it that does not and is shown by the wire tie that is in it.  

 

What is the number of that terminal? Is that the only one without a wire on it? If not, which other terminals don't have wires connected?

[Bloo]

5 minutes ago, LAS VEGAS DAVE said:

 

I have done all I can with the pictures. The important thing that you seem to miss is there is a terminal that should have a wire in it that does not and is shown by the wire tie that is in it.  I know what is wrong and I proved it as my post above explains. It is not the

 switch that is the problem. Thanks for your replies. 

 

Dave:

 

Yes, I see what you mean about the missing wire. I really do! The thing is, you DO have one end of that wire at the headlight. I understand that the other end should be connected to that terminal.

 

The other end is SOMEWHERE, connected to something! It has to be because your light is working on position 3. The implication is it must be there, and it must be connected somewhere it shouldn't be. I hope you find it!

 

All the best

[LAS VEGAS DAVE]

Bloo, you are right. I have to find where it is connected at my switch. It may be fixable if I can find it. This means once again becoming a pretzel with a test light under the dash. Thanks I am going to re evaluate the whole situation. I made the MISTAKE of thinking there is supposed to be TWO wires on the rear of the fender board, that is not the case. Two wires are in the front of the fender board terminal as it should be. OMG this is confusing. The problem is it is almost impossible to read the wire numbers or change the terminals while I am under the dash. I am 6 ft and 215 pounds.

 

Edited November 25, 2017 by LAS VEGAS DAVE (see edit history)

[MCHinson]

Dave, If you can take some photos of the wires on the switch terminals, possibly by using a cell phone camera, we can probably figure it out for you based on the wire colors. The wires all have their own color codes which will help identify the problem. 

[LAS VEGAS DAVE]

I just spent a miserable time under the dash checking every wire and their number from my YNZ harness to the switch. They are all where they should be except for the #9 terminal as numbered and shown in the 38 shop manual page 270. THAT TERMINAL IS EMPTY and my YNZ wiring diagram shows wire number 4 from the YNZ harness should be hooked to it. The problem is no wire #4 wire coming from the YNZ loom leading to ANYTHING, it is missing! There has been some problem at some point with the YNZ loom under the dash as it has some wires that are spliced leading to the body socket and something got hot under there at one time and discolored some of the insulation on them. My hunch is that the #4 YNZ wire was snipped at that time. All the lights work in each position in high or low beam as they should  EXECPT the drivers side LOW BEAM in position number 4. I am going to live with that as I see that in order to make it work where IT WOULD BE PERFECT and I would be happy I would have to install a new loom which is to much work and expense for the gain.  

[MCHinson]

Dave,

 

I will make you another offer. Bring the car to the 2018 36-38 Buick Club tour and I will do my best to fix it for you for free. Since the driver's side low beam works in position 3, we know that a wire to that bulb is making its way back to the headlight switch. I suspect that if I can see it, I can figure it out and fix it so that it will work properly. Other than that, there is no way we can help you without seeing the wires at the switch or a photo of the wires at the switch.

[Gary W]

The size difference between the two switches I have:

 

 

I THINK the bottom is for the Century?  All I know for sure is that the top is for my Special.  And, after using a test light, the internal connections are the same.

 

 

Difference is the larger center "triangle" in the lower switch.  All three are the same "smaller" size in my special switch.

 

I don't know why my lights were on when the switch was fully in,  but I'm sure someone here will!

Edited November 25, 2017 by Gary W (see edit history)

[LAS VEGAS DAVE]

7 hours ago, MCHinson said:

Dave,

 

I will make you another offer. Bring the car to the 2018 36-38 Buick Club tour and I will do my best to fix it for you for free. Since the driver's side low beam works in position 3, we know that a wire to that bulb is making its way back to the headlight switch. I suspect that if I can see it, I can figure it out and fix it so that it will work properly. Other than that, there is no way we can help you without seeing the wires at the switch or a photo of the wires at the switch.

 

Thanks Matt, I appreciate the offer. 

 

[MCHinson]

4 hours ago, Gary W said:

The size difference between the two switches I have:

 

 

I THINK the bottom is for the Century?  All I know for sure is that the top is for my Special.  And, after using a test light, the internal connections are the same.

 

 

Difference is the larger center "triangle" in the lower switch.  All three are the same "smaller" size in my special switch.

 

I don't know why my lights were on when the switch was fully in,  but I'm sure someone here will!

 

Gary,

 

According to the parts manual, all 1937 Buicks use the same switch and all 1938 Buicks use the same switch. The 1937 and 1938 have a different  headlight switch part number. Based on observing my 1938 Century and my 1937 Century headlight switches, I am fairly certain that the short switch is the 1937 switch, part number 480-W, and the long switch is the 1938 switch, part number 1994501.

 

I have not opened up my 1937 switch, so I am guessing that the center contact should be the same wider style as the 1938 switch. If the short switch is the rebuilt one that had the lights on when they should be off, I think that the problem might be that it should have the same wider center contact as the other headlight switch.