CJ7 Brake light issue - JeepForum.com
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post #1 of 15 Old 02-13-2020, 07:44 PM Thread Starter
rscottdfw
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CJ7 Brake light issue

I'm new to working on a jeep, so i apologize if this is too easy, but the brake lights don't work on my '84 CJ7. tail lights work. blinkers work. fuse is good. replaced brake light switch (which was a pain!), still nothing. Looking for suggestions how to trace the problem. thanks

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post #2 of 15 Old 02-13-2020, 08:13 PM
John Strenk
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do your emergency flashers work?
If not it’s a a fuse. The brake light and emergency light share the same fuse.

If that’s ok the you will need a test light.
Check both sides of the plug on the brake light switch on the brake pedal.
One side of the plug should have constant power. The other side will have power when the pedal is pressed down.

If no power on one side check the switch is adjusted properly.
If no power on either side then go back to fuse. Some times the socket gets corroded and not make contact.
If it’s ok then you have a broken wire between the fuse box and switch.

If yo do have power then check to see if the turn signal plug is pushed in all the way.
Check if the power from the brake switch is reaching the turn signal plug.

If there is power then there is a problem with the turn signal switch.
If no power at the turn signal plug then you have a broken wire someplace.

Since the turn signal lights work, there is no need to go further than the ts switch.
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post #3 of 15 Old 02-14-2020, 11:57 AM Thread Starter
rscottdfw
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thanks....flashers are not working so i'll check fuse box again.
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post #4 of 15 Old 02-15-2020, 12:32 PM
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Would that brake pedal switch cause the light at speedometer to stay on? Everything here functions but that darn light started coming on and won't shut off. I played around with the pedal and its switch and it worked (went off); for only about 3 days. Can't seem to find the issue. MC has fluid too. . . . do I need to bleed brakes again?
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post #5 of 15 Old 02-16-2020, 01:28 AM
John Strenk
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Which light is coming on? The brake warning light?

The brake light switch would have nothing to do with the brake warning light coming on.
But as you suspect a problem with the brake system could be causing the problem.
There is a switch in the combination valve below the master cylinder. If there is a leak in one part of the system then there is a piston inside the combination valve that will trip this switch and turn the brake warning light on.

Also the parking brake pedal will also turn on this light so if your brakes feel good, then look at the switch on the parking brake pedal .
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post #6 of 15 Old 02-16-2020, 04:09 PM
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Quote:
Originally Posted by John Strenk View Post
Which light is coming on? The brake warning light?

The brake light switch would have nothing to do with the brake warning light coming on.
But as you suspect a problem with the brake system could be causing the problem.
There is a switch in the combination valve below the master cylinder. If there is a leak in one part of the system then there is a piston inside the combination valve that will trip this switch and turn the brake warning light on.

Also the parking brake pedal will also turn on this light so if your brakes feel good, then look at the switch on the parking brake pedal .

Yes, the brake warning light inside speedo. The pedal feels good; two clicks down and it's tight. I'll look further into that switch.

I just checked underneath at the combination valve only to find out that it is mounted to the frame with only ONE bolt. Apparently the shop that replaced it (I didn't have the right tools at the time), took a small grinder to the previous CV to remove the 2 mounting bolts. I can see now why they didn't add the second bolt; the tubular Nerf bar is in the way and those are welded on nicely and in direct path of the second bolt. I only wish they had said something instead of me finding this out now. It feels secure however under the speed and road conditions the Jeep endures, I can only image it wiggles and causes air bubbles from it vibrating. Hmm?

Now I need to figure out how to secure that without un-welding the tube bar. PITA!
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post #7 of 15 Old 05-01-2020, 02:30 PM
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So I have run into the same problem. I had my dash unbolted and steering column out doing a heater box rebuild. I also switched out my speedo and added led lights just to speedo. When I went to check dash lights before I put it all back together I was having a lot of weird problems with lights and blinkers. Some times they would work And other times Blinkers wouldn’t work when parking lights were on. It seemed to change every time I checked it. I got frustrated and just put dash and steering column back on and everything miraculously worked except brake lights. So I checked the brake switch and it would have power on side of switch when off and both when on. I checked power to the turn signal plug on steering column and it was good. Flashers work. So is it a problem with the turn signal switch on the steering column even though the turn signals work?
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post #8 of 15 Old 05-01-2020, 04:37 PM
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I was just experiencing rear brake lights that would stay on after turning off and going inside. A neighbor came and mentioned my brake lights being on. This was happening on and off for about a month. It would trigger the brake emergency light inside speedo as well. For me, it was the elongated switch that is at pedal top and underneath steering column. I had to loosen both tightening nuts and move it forward (downward toward firewall) about 3/16". It works like a charm now. It was recently replaced when I did the MC. So, my guess is it was never fine tuned to the distance it needed to be. Play with that switch. Push the button in and out and see if you see anything happening. You'll need a friend to watch the brake lights or back it up against a wall the see the brake light reflection when they go on. That switch is a PITA to reach up and work with.
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post #9 of 15 Old 05-01-2020, 08:52 PM
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I’ve got the switch out where I can manipulate the button but the brake lights still don’t work. It seems that there is power to and through switch and even to the turn signal switch that is integrated with multiple wires on the steering column
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post #10 of 15 Old 05-02-2020, 05:57 AM
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Quote:
Originally Posted by mjfahr View Post
Iíve got the switch out where I can manipulate the button but the brake lights still donít work. It seems that there is power to and through switch and even to the turn signal switch that is integrated with multiple wires on the steering column
You could jumper the wires from the brake switch to the brake light wires goin to the rear of the jeep, if that works then you have a problem with the ts switch


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post #11 of 15 Old 05-03-2020, 07:13 AM
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Ok I’ll try to track those wires down. Thx
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post #12 of 15 Old 05-06-2020, 09:25 AM
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Well while I was at work I just decided I would go ahead and order a turn signal switch since it wasn’t too expensive. I found a YouTube video that was thorough. When I got to wiring the new harness has 10 wires where the old had 8. There is actually 9 wires on the opposite plugin but the 9th is at the end by itself and there doesn’t seem to be a metal connector in the turn signal switch for it. Also the wire colors aren’t the same but I assume that’s not a problem. Before I started cutting the old one out I wanted to make sure this sounded like the right switch for an 80 cj.
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post #13 of 15 Old 05-06-2020, 09:48 AM
John Strenk
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Some switches have connections that are not used on the Cj like Key buzzer

The extra connection may be for a PRNDL light if you have an automatic transmission.

Usually it's not a problem and you don't have to add or cut any wires.

There was some changes in the length of the connector between years and you can swap wires between the plugs or ask for the adapter plug.

The colors are not important.


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post #14 of 15 Old 05-06-2020, 10:49 AM
mjfahr
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Thx
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post #15 of 15 Old 05-07-2020, 08:36 AM
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After changing out the turn signal switch all is well. On to my next problem...
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