Brake Lights

[oldjeeplady]

Progress - Great job! Yes, a separate ground wire to each fixture ensures you have a solid ground.

From what you describe I am guessing your rear lights are not wired correctly or the wires are pinched and shorted. I would suggest you remove both rear light fixtures from the jeep completely and disconnect those wires and remove the bulbs. You should check the wiring from the dash connector back (unplug it first). There are some good pictures of this connector earlier in this thread. Check that each wire has continuity to itself and no other wires or the frame. Then check each fixture with the bulbs removed so you know which wire is running lights, backup lights, and turn signal/hazard. There should be three wires from each fixture. Go by function and not wire color. Label each wire by function as you identify it. Make sure you check both fixtures even if they have the same color wires they could be wired differently. There is one wire in the connector from the dash that goes to your fuel tank sending unit. The ground for the sending unit is usually connected to the frame, but often is not a good ground. I would suggest you connect the ground for the sending unit to the ground you run to the back for the lights. Some folks install a ground buss connector in the rear and then connect the lights and fuel sending unit grounds to that. A bad ground will damage a fuel sending unit right away. This is tedious work, but I am sure if you take it step by step you will solve your wiring issue.

And then you can help the next person that asks about this.

 

[mriplaybass]

The reason for your back up lights coming on is probably a bare spot in one of the brake wires contacting a bare spot on the back up light wire. Before you start pulling wires out, try this. With your ignition on so that the turn signals work, try each signal separately and see if either causes your back up lights to flash. This will tell you if you are crossed between a turn wire, and the back up wire. If you don't get the back up lights to flash this way, you are probably crossed with the brake switch wire. If this doesn't yield any results, I would do as already has been suggested and run ground blocks directly from the battery. We have done this in several locations on our Jeep, and have pretty much eliminated electrical problems.

One other thing to try before tearing things apart would be to work your shift lever in and out of reverse several times to eliminate the possibility of a stuck back up light switch. If the switch has completely failed, this won't work, but if it's only stuck, it could tell you where a problem is about to occur.

 

[Hillarie]

Thanks so much for the detailed instructions- it helps! I will update progress as it happens.


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[jammer1]

Anything to help. I love learning off this forum. Great group of jeepers.

 

[Hedgehog]

Someone that is unable to log on anymore reminded me to mention that your problem could be n the light switch connections. The plugs are famous for corroding and loosing contact. Mine had this problem along with a failing fuse box that threw seemingly random failures ..... another reason my wiring is being switched over to a painless harness.

 

[Hillarie]

Well it seems as I create problems while trying to fix things [emoji853]
The blinking issue has been solved. I now have running lights in the rear and driver rear turn signals. No passenger rear turn signal (both front work fine). No reverse lights now. And still no brake lights.

I found the brake light switch (I can see the white plunger engage when I push on the brakes) but that took awhile for me to find.
I also was able to find the fuse box (yes I know you are all rolling your eyes [emoji102]).
Back at it again this weekend. Frustrating.

I have not installed the grounds for the tail lights. Going to do that and see if it changes anything.

I keep returning to these posts for guidance- thanks so much!!


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[Lumpy Grits]

Bet the GND will make all the difference.
LG

 

[Hillarie]

I rigged a temporary ground from the passenger rear light to the firewall. It worked in my driveway. On down the road I went!!! Wahoo!!!
And then nothing. Passenger brake light out again. My rigged connection is still solid.
Ggrrr.

 

[Lumpy Grits]

Now-Run a new power lead with your dedicated GND.
Was the GND hard-wired or just 'clips' and such?
LG

 

[Hillarie]

The ground was hard wired from the firewall (2 nuts&washer) to the tail light housing. I am going to run a mother ground to the driver side tail light.

Do I need to remove the old ground?

In order to run a new positive do I need to disconnect the battery? I am leery of electrical things.

The forum has been down for a bit so I was not able to thank you promptly so thank you now!!


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[FLYNHYCJ7]

I rigged a temporary ground from the passenger rear light to the firewall. It worked in my driveway. On down the road I went!!! Wahoo!!!
And then nothing. Passenger brake light out again. My rigged connection is still solid.
Ggrrr.

You might want to check your tail assy. some times dirt and crude will get in the socket spring and not let the ground circut make a good conection.

 

[Lumpy Grits]

How are you attaching these temp leads?
Sounds like you may have lost the power feed side(+).
LG

 

[Hillarie]

How are you attaching these temp leads?

Sounds like you may have lost the power feed side(+).

LG

Here is the firewall attachment

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[Hillarie]

The taillight attachment is similar but is between the tub and the taillight housing.


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[Lumpy Grits]

Not a good connection/contact point for a GND.
Run a dedicated lead and attachment point, with a external star washer that will bite into the bare metal. You should also have a grommet in place where the wire comes through the sheet metal.
Why are you using solid wire and not stranded?
Respectfully,
LG

 

[Hillarie]

Not a good connection/contact point for a GND.

Run a dedicated lead and attachment point, with a external star washer that will bite into the bare metal. You should also have a grommet in place where the wire comes through the sheet metal.

Why are you using solid wire and not stranded?

Respectfully,

LG

I will make those adjustments.
I used solid wire because that is what I had. I can get stranded wire.
Thanks SO much for all the follow up!


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[Lumpy Grits]

A #10 screw and nut with an external star washer on bare sheetmetal, makes a great GND connection. Spray the connection with battery terminal spray to prevent corrosion/rust.
I would suggest either crimp or solder type terminals for this.
Good luck
LG

 

[Hillarie]

Well more issues. I replaced the ground with 12 strand and star washers but NO brake lights on either side now. I started looking for the brake light switch again and um is it possible to "lose it"? I cannot see any switch now. I still have tail lights.


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[Hillarie]

This is what it looks like from the brake arm going into the firewall. Hard to get a good pic so I can imagine replacing it is a bugger. But where did the plunger go? And I am not seeing any loose wires either.

So thankful you all have this great knowledge. I am stumped. Thanks so much!


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[mriplaybass]

Here is what your brake light switch looks like. Hard to see, but it's there!


You have to lay upside down on the floor to really get at it. At 6'2", I actually took the seat out when I had to work on ours.