Brake lights '51 Merc.

WABOOM

WABOOM

Senior Member
My brake lights no longer light up, and the turn signals have a few seconds delay before they activate. Information from my internet search is pretty light on info for this system.
The brake lights go thru the turn indicator switch as I understand, correct?
I can't figure out how to remove the turn signal switch. Can anyone tell me how to remove it?
I did have the front parking lights/front turn signal wires disconnected from the junction blocks last week to repair the parking light bezels. But I confirmed that my tail lights and signals worked correctly all around after I was done with the parking lights. I think this is coincidence, but anything is possible.
Also, I cannot find the circuit panel or fuse box under the dash. Please advise.
 
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Go back and check all your connections. If everything worked prior to you working on the front lights you have a bad connection at the junction block. Perhaps the connections came loose after you hooked things back up? Those junction blocks aren't the best set up for connections and if they are old originals the bakelite will crack and not allow a good connection. Once they crack they do not put good pressure on the copper sleeve inside. Also test your brake light switch to see if you have power to it and power coming back to the turn switch.
If your signal switch is inside the column, you'll have to pull the steering wheel.
 
Not sure how similar the Merc wiring is to the Ford, but see if these help any.
 

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Volume II of the 1949-51 Lincoln Mercury Overhaul Manual will tell you all about the turn signal operation and assembly as well as the circuit board behind the dash. If you own a 49-51 Merc you must have these books.
 

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Those are the little book reproductions. The original is all one full size manual. The wiring diagrams are not good for use in maintenance. I purchased the diagram that is laminated and I have copies of the diagrams that came with the different wiring harnesses that are available for restoration.

The wiring that extends down and out of the steering column jacket is soldered to the turn signal switch. If the old cloth & resin covered wire is breaking down you can get open circuits or short circuits inside there or under the dash where they intersect the terminal block. Those terminal blocks hold tight and require a tool to open the socket a bit to get the terminal pin out of the socket. The harness is fed up enough to either gain access for inspection or to fully remove the switch & harness assembly. I've been fortunate to find one new switch & harness assembly NOS that was upgraded to plastic type wire insulation. They are not easy to find though. I have soldered the new reproduction harness wires to them but the reproduction wire I used is larger in cross sectional diameter of each wire so its fat and doesn't want to fit down the column well. With care and patience it will work but if I ever do another one, I'm going to use aircraft type wire for a better fit. I'll just have to color the ends for identification since all aircraft wire is white.

The brake lights have to be cross controlled for the turn signals so that when the turning side lamp is on, the brake lamp will work on the other side. The old brake light switches can be repaired if they are still in relatively good condition. Both of my 1951 Mercury cars had to be rewired due to deterioration of the wiring.

The mid century Mercs don't have much for a fuse box. The power supply board is above the hand brake and is easier to get to if you remove that hand brake assembly. The board has the circuit breakers and the signal stat on it for turn signals. There are two fuses but they are only for interior lighting and the turn signals. All other external lighting is protected by the circuit breakers.
 
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I have brake lights! I unhooked the pressure switch wires and they came off very easily. The were also filthy. I jumped the wires and the lights lit up. I cleaned the prongs on the switch. Then I cut away the swelled/deteriorated insulation on the wire connectors. In addition to being dirty and corroded, one of them was extremely loose. I don't know how I ever had brake lights... (I might not have).
I cleaned them up really good with electronic parts spray and rolled up sand paper. Now the lights work.

Thank you for your responses.

Btw, I found the book that came with the car. I'll be studying it.
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WABOOM said:
I have brake lights! I unhooked the pressure switch wires and they came off very easily. The were also filthy. I jumped the wires and the lights lit up. I cleaned the prongs on the switch. Then I cut away the swelled/deteriorated insulation on the wire connectors. In addition to being dirty and corroded, one of them was extremely loose. I don't know how I ever had brake lights... (I might not have).
I cleaned them up really good with electronic parts spray and rolled up sand paper. Now the lights work.

Thank you for your responses.

Btw, I found the book that came with the car. I'll be studying it.
Click to expand...
Judging by the condition of your wiring, every connector, including every bulb to its receptacle needs attention/cleaning.
Have had similar problems that were due to bad connections or grounding.
Don't think the book will tell you that.
 
Great. Glad you found it and fixed it. As 51 MERC-CT infers, 49-51 Merc wiring connectors have much to be desired. Very poor. I guess FORD was skimping on materials during the Korean Conflict.
 
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I know that a re-wire is in my future, but is there a source for just the connectors if I need to just patch one up?
Thanks again guys.
 
Road Island Wiring sells connectors, but not sure they are correct for that late of a model. Sure there are other sources. Not original style, but boating supplies sell a lot of different electrical and wiring components.
 
I would suggest that after you clean all your terminals that you coat all your electrical connections with Dielectric compound. IMHO the best around (and what we use at my work) is Motorcraft PN. # XG-3-A. It comes in a 3oz tube & is also used for brake caliper grease. Just sayn. Bill
 
outlaw said:
I would suggest that after you clean all your terminals that you coat all your electrical connections with Dielectric compound. IMHO the best around (and what we use at my work) is Motorcraft PN. # XG-3-A. It comes in a 3oz tube & is also used for brake caliper grease. Just sayn. Bill
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I did put some di-electric grease on it. Thanks man.
 
The bullet & socket connectors are not easy to find. They are sort of unique to Ford products but they were sized like some of the after market stuff. Rhode Island Wire or his brother at Narragansset Reproductions may have some stuff. I prefer the crimp type even if you solder them. The machined type are solder only since they are too brittle to be crimped. Brillman also has bullets but you have to make sure you get the right diameter since there were several different sizes depending on the manufacturer.
 
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