Brake Light Wiring.... 1968 J2000 ... SOLVED!

[Gladi8r]

Hey Folks,

Do any of you seasoned veterans know where I can find a brake wiring diagram, or know how to troubleshoot? Does anyone at least know the basics? I am an electrical contractor here in California, so I know I'd be a quick study.

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The repair manual wiring diagram shows that one wire comes from the light switch, to the pressure switch, and then back to the light switch. But no detail at the light switch. As you can see in the picture above, it looks like someone tried to fix it at one point by using vampire taps, but whatever they did isn't working.

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Here's what I know:

All other lights work.
When I push in the hazard button, the fronts and blinker lights flash, the rears do not.
When I use the turn signal, the appropriate rear, front and blinker lights function properly.
The pressure switch was faulty (continuity test) and replaced with a new one that passes continuity.

Thanks in advance for any help you all can provide...

[AwesomeJ10]

http://oljeep.com/gw/elec/GW_wiring.html

[Gladi8r]

I appreciate it, but the only diagram I could find on that site is in my service manual. And it is the 3rd photo I posted above Did I miss one? I looked through that site pretty well...

I've been scouring the internet since I posted this, and it looks like the brake switch power goes though the column signal switch? Can anyone confirm or deny this?

[Gladi8r]

I found this on another forum for a different year and make, but I figure I'll give it a try tomorrow. I'll let you all know how it goes... In the mean time, if anyone has a specific turn signal/brake light schematic, that would be awesome!!

Ristow:

"the turn signal switch,in the steering column.the power to the brake lights is send through that switch,because,when you use the turn signals,that switch determines which light flashes (signal) and which light shines steady (brake light).if the turn signal is not engaged,both brake lights will shine.i had the same problem as you,had signals,hazards,tail,but no brakes.looked everywhere,finally traced power to the column,power was going in,but not coming out of the switch.i simply had to clean the switch assembly,my truck is a working project,a little rough so i just hosed it down with some solvent,while in the column,and shot some grease in there. if your truck is nice,remove the switch for cleaning and dielectric greasing,it's not that hard.try this,lean a piece of cardboard against the back of the truck on the drivers side,so you can see the tailights reflection on it.hold the brake pedal down,and firmly wiggle the turn signal stalk up an down,and fore and aft,see if they flicker.if not,clean the swith anyway,and move down the trouble shooting list."

[44bz]

It does go through the column switch. I had mine apart awhile back when I put a flaming river column in and I had to color code the old wiring to the new (the colors didn't match). I wrote it all down but now I can't find it...


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[Gladi8r]

Well thanks for teasing me j/k If you can find it, the karmic gods and I would forever be in your favor!

[Gladi8r]

So I got as far as taking the steering wheel off and exposing the wiring inside the column. I'm going to dig deeper tomorrow...

[carnuck]

The way I check is go to the stop light switch under the dash and first check if there is power to it. It's fused and always live so one of the two wires must be powered. If not, then check back towards the fuses. If there is power, I jumper the 2 wires and see if the stop lights come on. NOTE: Turn signal switch must be OFF and if you have column mounted 4 way Emergency Lights, push/pull the button to test if they flash, because those are share the bright element with stop lights and signals. If the Emergency Flashers work, then wiggle the switch the opposite way off because they stick 1/2 way and get corroded from lack of use.

At this point if you don't have stop lights lit, then tear into the column.

[Gladi8r]

Sorry it took so long to update! Looks like no one wants to touch this topic with a 10ft stick! lol

So anyway here's what I did:

I used a wire toner to trace each wire from both poles on the brake pressure switch:



One goes to the light switch, one of the brown wires (the other brown wire goes to the interior light BTW. Also, these wires are +12V, constant hot) shown below:



The other goes into the steering column and attaches to the hazard switch (the brown wire attached to the switch just below and between the yellow and black wires):



I used a jumper wire and found that the light brown wire (attached to the underside of the hazard switch) feeds the lights themselves. Every time I'd close this circuit with the jumper wire, the brake lights would come on. The problem: The hazard switch is bad. The short term solution: Cut the wires and solder them together, then shrink tube them:



Then put it all back together:



The great news is that I found a brand new hazard switch/turn signal harness/assembly on the PartsDude4x4.net:

http://stores.partsdude4x4.net/switch-d ... al-signal/

The guy who runs the site is a Jeepster enthusiast. I called him and he was really cool. I went ahead and ordered it on his website along with some various other parts and they were here in two days! He has all kinds of FSJ parts. He even said that he is working on manufacturing OEM spec steering wheels!

I hope this post will help someone in need!

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[carnuck]

Sounds like a mess! Last pressure switch style I had blew off and emptied my fluid, causing a crash with my other Jeep J10! Power should come in from 12V+ and then to column.

I converted to "universal" under dash switch.

[Gladi8r]

Good tip! Thanks