Brake light and misc electrical troubles

[damname101]

1981 CJ5

Hey all

I bought a CJ5 for the old lady and it is plagued with many issues that need addressed. We took the jeep out for a long drive last night and the brake light stopped working. The tail lights are fine....it's just the brake lights.

First thing i did was check the fuses but there doesn't seem to be a fuse for the brake lights....at least as far as i can tell. They are labeled. I do see the tail light fuse though. Pulled every fuse and check for continuity. I also looked for the switch near the brake pedal that activates the brake light....didnt see one.

What i need to know is where to go from here. Like locations on key systems tied to my issue, location of electrical wires i will have to trace and so on.

Can anyone please help?

 

[hdgapeach]

Sounds like you'll be needing to invest in a shop manual with a good set of wiring diagrams.

By the way, welcome to the jungle, hysteria, hobby, insanity, train wreck,......whatever you want to label it!!

I would think there ought to be a fuse and a brake light switch unless you have hydraulic pressure activated switches (extremely doubtful). Both bulb filaments blown??? If so, you might have a brake power wire rubbing to ground (just one of many possibilities).

One of the chain store parts houses has online repair guides that include wiring diagrams (I think Auto Zone). You may have to sign up to access and I'm not sure they have diagrams that go back to our era of vehicles. Might be worth a shot until you get some paper diagrams in hand.

 

[damname101]

Sounds like you'll be needing to invest in a shop manual with a good set of wiring diagrams.

By the way, welcome to the jungle, hysteria, hobby, insanity, train wreck,......whatever you want to label it!!

I would think there ought to be a fuse and a brake light switch unless you have hydraulic pressure activated switches (extremely doubtful). Both bulb filaments blown??? If so, you might have a brake power wire rubbing to ground (just one of many possibilities).

One of the chain store parts houses has online repair guides that include wiring diagrams (I think Auto Zone). You may have to sign up to access and I'm not sure they have diagrams that go back to our era of vehicles. Might be worth a shot until you get some paper diagrams in hand.

I think train wreck is about right! It is pretty but has lots of rust to fix and the floor is starting to go. This thing has alot of electrical issues. I will take any help i can get. My main issues are locating the wires involved and tracing them which is proving to be a headache. I dabble in working on cars to a somewhat medium high level...but i am mainly a computer repair nerd.

 

[Torxhead]

You should be able to find a wiring schematic for your CJ online if you know computers, if not the Haynes Jeep CJ Repair manual has one in the back area of the book. If you look up at the top end of the brake pedal you should be able to see the black stoplight switch opposite of where it comes in contact with that top end of the pedal. That is a good place to start. Not sure which fuse is for the switch, but on my '86 it is labeled "clk haz/stop" to help you get started.

 

[damname101]

ok heres where i am at. replaced the brake switch...easy enough but no fix. tested for juice at the tap point for the trailer lights with brake pedal pressed in and no juice. it is located near the point where the conduit dissaperas into the body near the tail light boxes. the only juice back there is the fuel gauge pink wire and the tail lights.

so i began to attempt to trace the wires. i see where the wires go into a connector that is connected to the steering column. when i measure voltage there, i get nearly 12v for one wire with brakes pressed. and then the wire dissapears up the steering column near the horn.

something in between the brake switch and the wires heading back to the brake lights is not connected all the sudden.

i cannot find a wiring diagram for an 81 CJ5 at all. nearest i can find is a late 70s diagram. does anyone know where i can find a diagram other then going out and buying a manual?

 

[hdgapeach]

Searched around and found 'bout everything but a diagram for an '81. Register on Auto Zone and you'll have access to their free online repair manuals. They include pretty good wiring diagrams. Might be your best bet for free.

Buying your own Haynes manual will be worth every penny in the long run. If you get one, you'll need a magnifying glass to read it unless you have a child's eyes!

 

[Fastatv]

ok heres where i am at. replaced the brake switch...easy enough but no fix. tested for juice at the tap point for the trailer lights with brake pedal pressed in and no juice. it is located near the point where the conduit dissaperas into the body near the tail light boxes. the only juice back there is the fuel gauge pink wire and the tail lights.

so i began to attempt to trace the wires. i see where the wires go into a connector that is connected to the steering column. when i measure voltage there, i get nearly 12v for one wire with brakes pressed. and then the wire dissapears up the steering column near the horn.

something in between the brake switch and the wires heading back to the brake lights is not connected all the sudden.

i cannot find a wiring diagram for an 81 CJ5 at all. nearest i can find is a late 70s diagram. does anyone know where i can find a diagram other then going out and buying a manual?

If your talking about the connector on the steering column, did you check both sides of the connector for 12vdc? If not try it....and there are two wires there for the brake lights. If you find 12 vdc on one side of the connector, and not the other side, then pull the connector apart, clean it with contact cleaner, the blow it out ( both female and male ) with compressed air, apply dielectric grease, then snap back together. This is what fixed my brake lights. Simply a dirty connector.

 

[damname101]

If your talking about the connector on the steering column, did you check both sides of the connector for 12vdc? If not try it....and there are two wires there for the brake lights. If you find 12 vdc on one side of the connector, and not the other side, then pull the connector apart, clean it with contact cleaner, the blow it out ( both female and male ) with compressed air, apply dielectric grease, then snap back together. This is what fixed my brake lights. Simply a dirty connector.

yep that be the one. i do measure 12v on both sides of it while the pedal is pressed. so today i am going to retrace my steps. i have been working on the speedo cluster a little bit. thats when we think this started. i was replacing the old bulbs with the led bas9 bulbs. so im going under the dash today to recheck those connections and if that doest yield a fix....im going to run a jumper from the steering column connecter to the wire that runs to the brake lights. that is as soon as i can identify the brake wire at the rear of the jeep AFTER the connection near the tail light itself.

while this should fix the brake lights...it still doent fix the issue which may be affecting other systems. i did end up with a schematic finally thanks to a member here. it is vague though when it comes to the stop light wire.

 

[Fastatv]

yep that be the one. i do measure 12v on both sides of it while the pedal is pressed. so today i am going to retrace my steps. i have been working on the speedo cluster a little bit. thats when we think this started. i was replacing the old bulbs with the led bas9 bulbs. so im going under the dash today to recheck those connections and if that doest yield a fix....im going to run a jumper from the steering column connecter to the wire that runs to the brake lights. that is as soon as i can identify the brake wire at the rear of the jeep AFTER the connection near the tail light itself.

while this should fix the brake lights...it still doent fix the issue which may be affecting other systems. i did end up with a schematic finally thanks to a member here. it is vague though when it comes to the stop light wire.

You might hold off on a jumper. Go to the left rear of the jeep, look up under the qtr pnl and you will see a 3 or 4 wire connection for the tail lights. Disconnect, clean/dielectric grease as mentioned before, and slightly squeeze the female portion of the connector with pliers. This will tighten up the connector....but squeeze only slightly. Plug back together and see what you have.

 

[damname101]

You might hold off on a jumper. Go to the left rear of the jeep, look up under the qtr pnl and you will see a 3 or 4 wire connection for the tail lights. Disconnect, clean/dielectric grease as mentioned before, and slightly squeeze the female portion of the connector with pliers. This will tighten up the connector....but squeeze only slightly. Plug back together and see what you have.

ok ill try that right now brb.....

 

[damname101]

no good. i did find a short leading to the passenger tail light though.

so i did it. i ran a jumper from the brake switch (pink or red) to the green w/black stripe wire near the tail light where the trailer tap is. working now...

 

[Torxhead]

There is quite a distance between the brake light switch and the tail light for things to go wrong. There should be a rear wiring harness the runs along the lower drivers side, as it runs up under the dash there is a plug for that harness. You could disconnect that plug to try and locate which side of that plug the bad wire is, or it could even be in the plug itself. That rear trailer tap must be an add on so make sure there there are no problems with the connections there.

 

[damname101]

There is quite a distance between the brake light switch and the tail light for things to go wrong. There should be a rear wiring harness the runs along the lower drivers side, as it runs up under the dash there is a plug for that harness. You could disconnect that plug to try and locate which side of that plug the bad wire is, or it could even be in the plug itself. That rear trailer tap must be an add on so make sure there there are no problems with the connections there.

i know the plug of which you speak. i already tested it and it checks out. the issue i somewhere inbetween the steering column connection and the lights. i can only trace the wires to the steering column and then they vanish up the column.

the brake switch... a red wire with black stripe which carries 12v connects to the switch. the output of the switch is a pink wire. this pink wire connects to a long plug which is mounted to the column. from there it goes up the column...never to be seen again. this is as far as i can trace the stop light wire until it appears again right before that connector you speak of.

i know i didnt find the issue but i did manage to temp fix it by running a jumper.

 

[Torxhead]

What I see in a '80-'83 wiring diagram is that pink wire from the brake light switch goes into the turn signal switch hazard light system. A possible wiring short could occur there, do the hazard lights work? There is what looks like a plug at the steering wheel.

 

[damname101]

What I see in a '80-'83 wiring diagram is that pink wire from the brake light switch goes into the turn signal switch hazard light system. A possible wiring short could occur there, do the hazard lights work? There is what looks like a plug at the steering wheel.

yes. everything else works as it should. the pink wire turns into a white wire on the other side of the connector and goes up the column. its strange... i dont see what business that wire has in that area. i have spent a few hours studying that diagram. i am able to put the visual to the diagram but even then it just doesnt make sense.

i got sick of trying to find the short and bypassed it entirely. i ran a jumper from the pink wire to the green wire with a black stripe. now the brake lights work fine.