Do a Google for 51 Merc wiring diagram.
There is a site called "vanpeltsales" alot of diagrams there ,cant get site to work here,good luck.

 

Tried that and found that site, but no turn signal wiring diagrams.

Anyone else? Thoughts? Been trying for a couple days and can't seem to find it. I thought I had it using a multimeter but its not playing out like it should.

 

There is a lot going in in the turn switches

power from the brake switch should flow thru the switch to both of the REAR signal lamps when the swith is in the neutral position.

This will be battery power---available ALL the time

When you are signaling a left turn---the left brake circuit shuts off and power is supplied thru the flasher unit to the left rear lamp AND the front turn.

This will only happen with the key in "RUN" or "ACCY"

Just the opposite will happen when a right turn is signaled.

I don't have a diagram but this is how they work.

You will actually have 2 wires supplying power to the switch---one from the brakes and one from the flasher.

Hope this helps you to figure things out.

Bryan

 

It does... thank you. I had figured that all out the long way by disassembling the switch and just plotting continuity between posts, but the problem I was having was that all my logic wasn't playing out in the actual operation of the switch.

BUT.. I figured it out. The switch has the mechanical body and then the "printed" board on the back. I found a crack in the back which allowed the contact board to bend out of the way when I slid the switch to the desired position. I was getting intermittent continuity.

The good news is that I figured it out. The bad news is... I've exhausted about 15 possible sources for replacements and the best I can come up with is an aftermarket turn signal assembly that mounts to the outside of the column. grr. I had a perfect 51 switch and then found out it won't work. I could maybe epoxy the board, but I'm on the shop's dime and I don't think the boss would be happy with trial and error.

Thanks to all... Problem solved... or at least figured out.

 

In fact...

Since I did figure it out and didn't find it on the web... here is my own diagram.

 

re

It occurs to me that Lucas[prince of darkness] made a widget that did what the fancy switch does, and there might be a us version. If you cannot fix the switch properly, you might be able to make use of such a thing. I also don't know how many bulbs are in your taillights, you could re do the bulb receptacle to take a 2 filament bulb and again not have the dual purpose issue

 

Is this a cable operated switch???

If it is---could you possibly use a switch for a late 50s, early 60s chevrolet??

If you could make this work--then all you need to do is to move a couple of wires around.

This switch is common and it is also reproduced----I think it may even be in my 64 Chev C-10

just tossing it out for ya

 

Its not cable operated. Its a mechanically linked switch that lives under the steering wheel. I have looked at a dizzying array of switches. Even 51 Ford switches are different from the 51 merc.

I'm sure I could make something work, but this is a complete survivor 51 merc. Normally we would do the rod mentality of use-what-works, but since this is a pristine example we have gone to great lengths to pull out the original wiring and solder in new wires in its place. Don't ask me about the fuse panel unless you want a 3-day dissertation.

Fortunately I did find ONE switch and I'm having it shipped, so I can start the soldering process over again.

 

It occurs to me that Lucas[prince of darkness] made a widget that did what the fancy switch does, and there might be a us version. If you cannot fix the switch properly, you might be able to make use of such a thing. I also don't know how many bulbs are in your taillights, you could re do the bulb receptacle to take a 2 filament bulb and again not have the dual purpose issue

It is currently a dual-filament bulb. That's where the problem is. In order for the brakes and turn signals to work properly, the column-mounted switch has to house all of the wiring for the front and rear turn signals as well as the rear brake lights - simultaneously shutting off the right brake light while the right turn signal is on, AND properly distribute the incoming 6v sources to their proper contacts.

It gets complicated :sweat:

 

The Lucas relay is a DB 10 brake light/indicator relay. I think part no. 140105 cost about $170 or so. Tom F

 

hey man, thanks for going the extra mile and putting an illustration together. I just took my column apart yesterday and I was like WTF?!?! it's been a few years since your original post but I appreciate your efforts!

 

I know this post is old....... I have repaired some old boards by using fiberglass resin and some nylon material (like from a umbrella) and laminating the nylon to the back of the board, couple of layers and it's solid, If the contacts needed to pass thru the back, I simply cut slots in the nylon etc.... Little trim work when dry and ended up with a refurbished board