1937 Cadillac Headlights

[jackworstell]

We have 1937 Special which has the fancy headlight switch with the
"passing beam" feature.

When the headlight switch is in passing beam mode the drivers side head light
is supposed to toggle between high beam and low beam
when depressing the dimmer switch....however the
the passenger side headlight is not supposed to change.
when the dimmer switch is depressed.


But ours works backwards.   The passenger side headlight toggles and the
drivers side doesn't change when the dimmer switch is pressed.


Can anyone help with this ?


A new wiring harness was installed a few years back and it sure sounds like
some wires got crossed.   But the headlight switch/headlight wiring
is not easy to understand and I can't figure which wires were switched ( if in fact
this is the cause )

Jack Worstell

[harry s]

Jack, I put a new wiring harness in my '37 and have the same situation. I called the vendor and they weren't too interested in talking about it. I bet you got your harness from the same vendor (abc....xYZ).     Harry

[jackworstell]

Harry

…yep...same vendor.     


Jack

[J. Gomez]

The way you explain it the foot switch would only go to the driver side headlight for the high/low function while the passenger side would go directly to the headlight switch.

I would guess both of the headlights have individual path to the headlight switch.   

How is the wiring diagram showing the foot switch going to the driver or passenger side headlight?

It may be as simple as flipping the wires at the headlight switch position for the right and left side. Although the color code would be reversed at the headlight switch from the original wiring diagram once they are flipped. 

[jackworstell]

Here's the wiring diagram showing the headlight switch.

It has 9 wires going to it.   Plus wires to power the accessories...radio and heater.


It is difficult to trace the wiring in the car because

........it is  hard to get to all of the headlight switch to
           see the various connections
........the small number tags put on the wiring harness by the vendor
          ...some are missing and some are no longer ledgible.

Jack Worstell

...edited to include the wiring diagram
...second edit...to correct the label of the wiring diagram

[jackworstell]

Here's the wiring diagram.....this time correctly labelled as  Cadillac....not incorrectly labelled as Buick

Jack Worstell

[J. Gomez]

Hmm well that is really interesting the wiring diagram shows the foot switch only controls the right side (passenger) headlight for low/high beams in other words single versus dual filament active since both are rated at 32CP.

Somehow the headlight switch is the one that key-in the connections depending on the position. Also, not sure if your new wiring hardness is correctly made per the wiring diagram or if they may have reversed the layout. 

I’m not sure how the headlight switch makes contact on all 3 positions between the terminals, someone may need to chime in as I’m just theorizing with these functions.

There are a few older post that you can check in the interim not sure if they will be of help in your issue.

http://forums.cadillaclasalleclub.org/index.php?topic=88493.0
http://forums.cadillaclasalleclub.org/index.php?topic=114016.0
http://forums.cadillaclasalleclub.org/index.php?topic=98595.0

Good luck..!

[harvey b]

does it matter where the switch is set,on mine the switch is worn?,if i pull it all the way back it works as it should,if i push it in a little bit,it will act weird?I too used a harness from YNZ,went in fine,was really impressed with how the wires seemed to fall into place,the hardest part was the headlight switch,9 wires,took some thinking to get them in the right order,dont know what is front or left or right side?,i still have the instructions that came with it,i could post them if they would be any help,they are quite vague as to where wires do go,I dont have the original bulb in my right lite,so i cant say if they work as intended,but the bulb does go to high like it is supposed to.It was a one year only thing,Im sure others have had problems too. Harveyb

[J. Gomez]

It would be beneficial knowing how the contacts made between each position at the headlight switch. That way it would be easier to follow the wiring diagram as to which wire will be connected to the power source and how they are switched under each position.

There is contact #11, #9 (which also extends to #12), and #7 on top and #4, #3 and #2 on the bottom for the headlight, power would be #1 according to the wiring diagram.

The footswitch just switches from “B” to 1 or from “B” to 2. So its function is simple but since there is a wire from 2 going over to the headlight switch #4 (drive indicator) that may extend power over to the left side lights via the headlight.

Hypothetical if e.g. wires at the hardness are reversed between #11 and #2 the operation would be different between the right and left side.   

[J. Gomez]

Also forgot to add;

If there an easy task of removing the headlight switch from the panel, you can verify if the new wiring hardness is correct.

Removing the wires from the headlight switch (mention above) which are for the headlights and jumper each to a power source you can verify if those are going to the correct light(s).


So e.g. terminal #2 wire would go to the “City” dash lamp and to the left headlight upper filament, terminal #9 wire should go to same headlight lower filament, etc., etc.

It may seem the wiring hardness was setup incorrectly since three folks are having the same issue with the same new hardness. 

[harry s]

Jose,  I had the same thought about switching wires and got myself switched into about every combination I could think of. I also tried matching the vendor instructions with the factory wiring diagram and got nowhere. I came to the same conclusion of a defect in the harness. I had hoped the vendor could shed some light but no help from them.      Harry

[J. Gomez]

Jose,  I had the same thought about switching wires and got myself switched into about every combination I could think of. I also tried matching the vendor instructions with the factory wiring diagram and got nowhere. I came to the same conclusion of a defect in the harness. I had hoped the vendor could shed some light but no help from them.      Harry

Harry,

That is unfortunate especially when we are in need and depend on vendors for our classic cars to keep them running.

Trying to find where the error may be in the hardness will be like trying to put a puzzle together, it can be done but it requires a lot of trial and error.

I follow the wiring diagram and notice all of the wires from the headlight switch are direct connections to the headlight sockets and to/from the foot switch. The only exception were the one from terminal #2 which splits over to the “city” dash lamp and terminal #4 which splits to the “drive” dash lamp.

If the color coding is correct and the wires are run correctly in the new hardness doing a continuity or applying power to each wire at the switch end could shed some light  in finding the problem.

Now if the fabricator somehow reversed the wires (since they have the same color code trace between them) going to the headlamp left-to-right and vice versa that would be a nightmare to fix.   

But again taking the headlight switch out could be the biggest problem, not sure how difficult is on the 30ish cars.   

[harvey b]

The switch is not hard to get out,its the wires attached to it that make it hard to maneuver down so you can work on it,gets pretty tight in thereit would help if you remove the speedometer,it gives you a better look at it.Make sure the battery is disconnected when you are taking it out,it will short out if it hits a ground spot. Harveyb

[jackworstell]

Harvey

Please clarify....after installing the new wiring harness....did you run into the
problem with PASSING BEAM mode as I did ( as I described in the first post of this thread ) ?

Jack Worstell

[harvey b]

I did not have any problems with my harness,it seems to work fine as it is.Guess i got lucky? only trouble i had was the high and low beam wires were reversed on the blocks at the rad shell area.The only sketchy part of it all is the switch itself,if i position it between the detents,it does all kinds of funny things,but if it is set right the lights seem to work fine,have you tried moving yours a little one way or the other and see if it helps,could be worn inside on the contacts?You would have to be careful if you were to swap wires from one terminal to the other,the switch is not marked very good,only a drawing to show the terminals,none are numbered,at least i never seen any marks on mine. good Luck  Harveyb

[jackworstell]

Harry
     You are to be commended for trying to trace out the headights/headlight switch    circuit.
I couldn't work up the courage to attempt it:

      First, the switch is hard to release from the dash ( I guess Harvey has a technique for this
      I haven't mastered )

       Secondly once the switch is out there is a nest of nine wires to deal with and there
       is very little slack in any of them.....such that even when I remove the front seat
       I have to lay in the floorboard in a contorted way to 
       hook up jumper wires, voltmeters, ohmmeters etc

       Thirdly these wires go into a harness and there is no way to see if
         any of the wires branch out....without removing the harness
        sheath ( and I'm not about to tackle this....)

We have a 1937 Buick Special that has essentially the same headlight switching system and it had the same problem with PASSING BEAM mode. It has a reproduction wiring harness of
unknown origin....it was already installed in the car when we got it.

We fixed the Buick like this

        On both the DS and PS  sides we removed low beam and hi beam wires
         from the two small terminal boards located not far from the headlight.

         Then added about 40"  extensions to each of these four headlight wires

          Then on the DS attach the two extensions ( from the PS )
           to the coreesponding terminals for hi beam and low beam on the
          DS small terminal board.

           Then on the PS attach the two extensions ( from the DS )
            to the corresponding terminals for hi beam and low beam  on the
            PS small terminal board

     This takes a little time but it works and there is no guessing.

Jack Worstell
   
   

[harry s]

I had the switch out and was lucky enough to have enough excess to work with. After putting the switch back in place I am resigned to put the issue on the bottom of the list for a later visit. I was disappointed at the vendor's seemingly lack of interest or willingness to off a solution. I wouldn't want to have to install a replacement harness but it would be nice for them to figure out the problem and explain.
Harry

[Brad Ipsen CLC #737]

This is an interesting problem which I also have on a 38 V-16.  I had decided not to try to track it down also since the light function is rarely used and the whole concept that Cadillac was trying to do doesn't really apply to roads today and our collector car driving.  Now with everyone having this problem it must be harness error and not an installation error. I don't remember where it is but YZ has had a DS PS error on something else that is chronic on several harnesses I have purchased and it has not been corrected after I pointed it out.  It is just in the directions and not in the harness or color codes of the harness.  I have 38-60S harness drawing that I think I got years ago that may help in tracking down the problem.  This is an official drawing with lengths of all wires and internal connections and where they are in the harness.  It is not a just a schematic.  If anybody wants to tackle it with YZ I can make a copy.

[jackworstell]

Harry

From your experience tracing out the harness....would you say the problem is in how the harness is made or do you  think it is in the directions provided by the vendor ?      Or...?

Jack

[harry s]

My guess would be in the harness as trouble shooting and switching wires to the extent of my imagination didn't correct. The original wiring worked as intended so that would eliminate the switch. I have taken Brad's approach since that feature really doesn't enhance my night time (very little if any) driving. If the car is being judged and the judges are able to pick that flaw up they should be congratulated (lol).m     Harry