Brake Light Switch Failure???

[55 Fargo]

Hi all, last night on the way to the big city, some guy at a traffic light tells me I have no brake lights. I tell him there is only one, he says it wasn't working.

Sure enough it wasn't working, I tested it, wiring is good, the bulb is good, connected the 2 wires and the light works, the switch has continuity, when the brake peddle is pushed.

But no matter what I did the brake light do not work anymore.

Can the brakelight switch have continuity and still not allow currecnt to flow?

What is a good mechnical replacement, any ideas/suggestions, or should I replace it with an OEM type, I heard that a 1950s Chev truck switch works on our brakes.

The city ride was crazy in my old car, too much fast traffic, drivcers don't seem to have much respect for aold cars, big p/u trucks and SUV s with cell phones were the worse, I was doing around 60 mph on the freeway. Temp stayed at 165 to 170 the whole hours drive.Thanx Fred

[oldmopar]

You can install a mechanical switch. You may be able to find a better price other vendors have them. I had this one bookmarked because he a the install instructions

http://www.watsons-streetworks.com/brake_switches.html

http://www.watsons-streetworks.com/get_off_juice.html

[TodFitch]

The "signal light switch" as it is called in the 1928-33 Master Parts book is still available from the specialty old car part places. And I bet it is still available at your better local auto supply store, except that I don't have a cross reference number.

There are those who have given up on the hydraulic style switch and fitted a mechanically operated switch too. I am sure they will chime in on this thread.

However, it is not clear if your switch is bad.

To get to your observations: Continuity is the ability for current to pass. How did you test for continuity on the switch? On my car the brake light switch is on unswitched power and if you don't disconnect the battery ohm meter won't work properly.

You say you "connected the 2 wires and the light works". Each filament of your bulb is connected to one wire. Did you connect each one, one at a time to the battery and see if each one was okay? Where did you get access to the wires (at the lamp socket or under the hood)? Basically it is not clear to me that you have actually checked that the wiring is good. It is easier to check the voltage/power at the socket using a test lamp than what it sounds like what you are doing.

Also, a classical electrical fault where the lamp lights if you ground one of the two wires to the socket and apply power to the other is that the socket is not grounded properly. From your description, this has not been ruled out.

[Young Ed]

Fred my original switch failed rather quickly but my replacement from Napa has been doing just fine. Only issue was I had to switch to female bullet connecters on my wiring. It was backwards of the old one.

[Tim Frank]

If there is continuity between the switch terminals, you have the equivalent of a jumper across the switch...i.e. for all intent and purpose, the switch is no longer there.

Doesn't sound like the switch is your problem.

Did you test for voltage at the fixture? Ground problems are more likely.

Rgds, Tim

[55 Fargo]

Heres the scoop.

I still only have 1 stop lamp, one wire to it from the switch under the hood down low by the rad on the drivers side. One wire comes in from the power source, when you touch these 2 wires together the brake lamp works, so no issue with a grnd or the bulb itself.

The OEM switch , when you connect the ohm metere to the 2 terminals without applying pressure to the peddle you get no reading (continuity), when you push on the brake peddle you get a reading on the Ohm meter, which tells me there is continuity in the switch.

Now when you connect the 2 wires with new terminal clips, or bare wires or alligator test leads to the 2 connections on the brake light switch, I cannot get the brake light to go on.

So can the switch have conituity, and still not work, not usually, so what might else be the problem?

I can run new wire, or whatever is needed, this baffles me because the meter shows continuity, but the switch does not allow the current to flow.............Thanx guys Fred

[55 Fargo]

Hi Tim, this is possible, but why when I connect the 2 wires that go to the switch the brake light goes on, could it be the terminals on the switch itself.

This switch shows continuity, when the brake peddle is pushed......Fred

[55 Fargo]

My local NAPA has one in stock for $8.00, gonna go get it, any special way of installing it, any problem to the brakes, ie will they need bleeding afterwards.................Fred

[Young Ed]

Fred I believe you will find it will fit in a 12pt socket. Go quick and you shouldn't have to mess with bleeding the brakes.

[steveplym]

Fred, when I replaced the brake lines on my '47 I damaged the hydraulic switch that worked on it at the time trying to get it out. So I had another one on the shelf and it didn't work either. I did what you did and touched the two wires going into the brake switch. Brake light lit up fine. That tells me that the bulbs, wiring, grounds and everything from that switch back to the lamp is fine. Also, power is coming into the switch thru the other wire. Seems no problems there either.

I'm betting your switch is bad, I went ahead and went with the mechanical switch so I wouldn't have to mess with it anymore. For $8 you might as well replace the hydraulic switch.

[48mirage]

Vintage Harleys also used a mechanical brake light switch that may be easier to mount than the street works version. I did the street works but if I was to do it again I would use one of the old HD switches from JP Cycles.

[55 Fargo]

Went to NAPA and bought SL134 switch, installed immediately, brake light works fine now.

The old switch had thick goop in it, when I redid all the brakes, I did not clean out th switch and terminal block, shame on me, thank God, the goop stayed in the switch..........Fred ps and $8.00 fix, 1 year warranty on the NAPA part

[Young Ed]

Fred did it have the proper bullet connectors?

[55 Fargo]

Yes it did, the males on the switch and females on the iwre as before on my OEM switch.

I know you mentioned yours was the reverse, but mine was the same, as above..........Fred ps NAPA sure beats waiting for a switch from Roberts or Burnbombs

[Young Ed]

Interesting thats the way mine is now too but the one I removed when I first got it was the opposite.

[steveplym]

Interesting thats the way mine is now too but the one I removed when I first got it was the opposite.

The one I replaced mine with was like that. I had to change the connections. When I found out that switch was older and didn't work thats when I threw it out. Maybe the older replacements were like that and then someone got smart and put the right connectors on them.

[Young Ed]

Someone on the truck side just posted a nice shot of what my initial switch looked like. I suspect these are close to fitting many things and they unified them to make them fit even more applications.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=79628#post79628

[Merle Coggins]

I just got a new switch from Napa for my truck. It has female bullet connectors. I noticed that they also showed some with male connectors. I can look at it tomorrow for the part # if anyone needs it.

Merle

[Tim Frank]

Fred,

From reading through all the posts in this thread let me see if my understanding of what you have done is correct.

1) You removed both wires from the switch and connected them; the brake light then worked. If that is correct, then you have indeed (at least in my opinion) verified all circuitry except the switch.

2) If you are testing the continuity of the switch, you should do it with the wires disconnected. To test continuity, you should have your meter set on ohms and test across the two terminals. You want a very large reading when the switch is open, a reading of zero when it is closed.

Rgds,

Tim

[55 Fargo]

Tim the problem is resolved, I bought a new switch, the rest is history.

The old switch showed continuity, but was gummed up, I guess it wasn't closing enough to allow the juice flow, so I installed a new NAPA switch, all is good now.............Thanx Fred

[steveplym]

Glad you got it fixed Fred. Those brake switches can get aggravating.