Brake light problems (and switch location)

You need a constant 12V source to one side and the lead to your brakes on the other. Pressure closes the connection sending 12V to the lights. Does that help?

 

i cannot stand the pressure switches.....my new one failed and besides it being a super pain to get to....i did not want to bleed the brakes...my solution was an easy fix..
http://www.thecj2apage.com/forums/getting-rid-of-the-hydraulic-stoplight-switch_topic23348.html

 

Yeah, I figured that out; I think the wiring is bad somewhere between the switch and the lights; I'm just not sure about the best way to go about finding it. I'm sure it makes no difference, but here's the wiring in the lights if it does:

right: https://www.dropbox.com/s/ta2d7h4qj5756ri/Photo Sep 20, 5 05 14 PM.jpg
left: https://www.dropbox.com/s/msyj0lyxucquhdw/Photo Sep 20, 5 06 14 PM.jpg

 

Of the two switches you show from Quadratec the first one http://www.quadratec.com/products/55217_00.htm is the type that Olds used for the '66 Dynamic 88 brake system. Mounted in a bracket that held it inline with the brake arm (swing from the dash style) and adjusted so that it is off when the pedal is in the full up position, and the second one http://www.quadratec.com/products/17238_01.htm is the one that goes into the end of the single mastercylinder or both positions of the dual mastercylinder.

 

the lights come after the switches, which are wired in parallel. You said you had no power on either side of the switch, so it must be losing connection upstream, between the switch and the source, not down stream. Just start tracing the wiring back, until you find the broken connection. You may have an in-line fuse buried in the wiring somewhere that has blown. For a test You should be able to jumper power from the battery positive to the power side of the switch, either switch will do, step on the brake and get power at the brake light.

If you are getting power in to the switch but not at the lights ( I am not clear on your earlier post) then remember the brake lights are then routed up through turn signals if it is stock. If you have the sparton turn signal switch you can open the cover it and test for the brake light power in there when you step on the brakes, but I don't remember which wire, you will have to trace it out.

 

The power goes to the brake switch then through the switch when the pedal is pushed hard and continues up to the turn-signal switch then comes back down the column going to the rear lights. If the power from the brake switch is not going to the turn-sig-switch then you will not have any stop lights.

 

I didn't realize it routed through the turn signal. To clarify, I DO have power on the hot wire at the switch, and the switch is apparently working fine, so I know it's the downstream wire. I was unsure of an easy way to test the wiring since all of it is bundled and difficult to get to. I'll try to find how it's routed to the turn signal and check there, because I'm pretty sure I'm not missing an inline fuse.

Can anyone explain that random fuse housing in this pic?: https://www.dropbox.com/s/ta2d7h4qj5...%2014%20PM.jpg It looks like a fuse goes there, but it's apparently too small for a "micro" switch, and bridging the gap with a wire didn't fix the problem.

 

Are you referring to the item on the left? It looks like the socket for a side marker bulb.

 

If so, why isn't there one in the other light housing?

 

the tail lights you have look like they are off a later cj? Like 76 and up maybe? Seems to have been a popular upgrade for a lot of early's. Try searching rockauto.com website to find the components. It may be that your left and right are off of different model years.

Early Cj-5s had 1 bulb with 2 elements, one for the lights, one for the brakes/turn. Similar to a trailer light like you can buy these days.

 

Yep that small socket that is empty was for a side marker bulb (bayonette type) and if you bridged it with a wire, you may have popped a fuse for the tail lights?

Normally you have a plug from the turn-signal switch that plugs into the main wiring harness. It should be a four terminal plug. What manufacture and model number is your turn-signal switch. The color code varies per model and I don't want to confuse you more by having you trace the wrong color wire.

 

The PO replaced a lot of the wires with his own, so most of the colors are off of stock. I just want to figure out how to trace the wiring to find the voltage drop without stripping off 25 feet of electrical tape "shielding."

 

Personally I would do it with an ohmmeter, add enough wire to the leads as needed to connect one end to the tail light connections, the other to either the turn signal connections or the brake light switch, depending on what you need.

 

A volt-ohm meter is a handy tool for the technician but the test light is better for the novice. The test light shows you what you expect to see or not see. In the OP's situation, the test light replaces the rear lights in this test without removing the wiring or bulbs on the circuit.

Back to the problem... You say your turn-signals flash both sides and front and back. You will have 5 wires that will show a flash with your test light. With key in the acc position (keeps from burning points during test) and the signal arm positioned for a left turn, you will read a flashing test light on four wires. This would be left front-left rear-load power from the flasher can and the indicator in the signal switch. Mark these wires. Now for the right turn you will do the same thing and mark these wires. You will find two wires will be marked twice. Those wires is for the pilot light and the flasher can. Now you have six wires marked. You have one wire left and that wire has to come "HOT" when the brake pedal is pushed. Let us know what you get at this point. HTH

 

Or a buzz-box continuity checker. Instead of having to watch for a light, the thing will buzz at you when you complete the circuits.
Not sure where you would find one though. It's been more years than I want to admit to since I last saw one.

 

Thanks for the advice. Will try checking the resistance of the circuit with wires on the leads to the switch, and then use the test light to start isolating wires. On a side note, I just turned the Jeep in to a guy to be painted. Was going to have only the hood fixed; now having the whole thing redone, including a lot of side work, so it will likely be the end of October when I return from a 3 week work trip to get around to troubleshooting the brakes, unfortunately. I do appreciate the ideas, though, and will get to it as soon as I get it back. I may get it early and be able to post some pics this weekend and let you know how the troubleshooting goes.

 

I'm with Walt on using the test light. Quick and easy and all you really need at this point. And, thanks Walt, for a great description of how to test and isolate the wires in that little magic box on the steering column.

 

Just an update; I haven't fixed the problem yet bc I was debating replacing the whole harness...but tonight I was driving and the brake lights were working fine. Didn't work in the garage, and they haven't for a while, and they definitely weren't working on the road a few months ago when I was last driving it. What would cause manual brake lights to only work when I'm driving?

 

Just moving the turn signal lever several times will help clean the contacts and also you may still have an intermittent ground loss like tub to frame.

 

An update just for your info, might prove helpful in the future...

Finally got the brake lights working. Here's the kicker: I tested the switch, both a few months ago and right before I fixed the problem. When I pressed the brake pedal, resistance across the switch contacts went from infinite/open to some random value like 20 Ohms (don't remember exactly). So I figured my switch was good, because I could see on the multimeter that the switch was actuating repeatedly with brake pedal depressions.

Turns out, I still needed a new switch. Popped one in, works fantastic. And all this time I was certain the switch was solid.

Side note: should I bleed the brakes? They seem to be working fine for now.