Brake Lights Stay On

[Focker]

'71 CJ5
I walked into the garage this morning and discovered that the brake lights were on all night. I unplugged the front brake light switch (the wires were hot to the touch) and the problem went away. My brake lights work like they should with only the one switch, why are there 2 switches?

 

[Hedgehog]

The front brake system is seperate from the rear system. If one fails you are still braking on the other. Hit the brakes and the lights come on, either the back only, the front only or both.

 

[Focker]

So...I have a bad switch? I bench tested it by checking the continuity. It seemed stuck until I cleaned it. Plugged it back into the brake system and it was fine until I pushed on the brakes. The lights are stuck on again. I'll swap switches to double check.

 

[007]

I just went through this on my 77, and it can be several different things.

Obviously the switch, adjustment of the switch, a bend in the flange that holds the switch, a brake pedal that loses pressure with the switch (which opens up a whole other can of worms).

Mine ended up being all of these, one right after the other. My lights were staying on so in pulling the pedal up by hand it moved the switch and later bent the flange holding it. On my Jeep you need (as IO puts it) an extra elbow in your arm to get to the switch so I just got mad and disconnected mine and put a micro-switch that presses against the linkage between the booster and the firewall. Not satisfied with that one either but it is what it is for now.

Best wishes with yours...

 

[GARGOYLEJEEPER]

Not switches, but a problem in the front brakes/and or master cylinder, not releasing the pressure.
This is a hydraulic/electric not like newer that are mechanical/electric.

 

[IOPort51]

kind of like they made a giant leap backward.

 

[GARGOYLEJEEPER]

Like Hedgehog said they went to a split system, so they needed a brake signal to the rear (so you did not get rear ended) even if you lost the rear pressure. Before that it was a single master with a pass thru T with the switch on the end, so if you lost pressure you lost brakes & lights. On newer went mechanical at the pedal & combo valve with warning light.
So on this system, if your brake lights are on you disconnect one to find out witch is not working properly. In this case it is the front, so diagnose the front - wheel cylinders, hoses, springs & master cylinder, something is not releasing the pressure back to the reservoir.

 

[Focker]

...so diagnose the front - wheel cylinders, hoses, springs & master cylinder, something is not releasing the pressure back to the reservoir.

Thanks!

 

[RatDog8o8]

I guess this "dual-system" doesn't apply to my '78 CJ7 .... I have one brake-light switch, buried upside down under the dash (major PITA to get to), and a "helpler spring" on the pedal arm to keep it pulled back away from the switch to keep any unintentional activation.

I was mainly checking to see, since my ride seems to be the "spare parts" vehicle from that year.....

 

[GARGOYLEJEEPER]

RatDog8o8,
You have a dual system, but the Engineers figured on the early systems if the master went out completely you would loose all brake lights. So they designed the new system without using hydraulics for the signal, and gave us a warning for a pressure loss with the combo valve, and a warning light that also tests as you try to start, and if e-brake is depressed so you won`t drive off with the e-brake on..
On the newer, you do not need to bend the tang, unplug and turn in or out as needed and replug. You need to be a contortionist, double jointed and or have a cockpit creeper.

 

[BusaDave9]

I walked into the garage this morning and discovered that the brake lights were on all night.

I'm confused. What lights are on?
The brake likes on the back of the jeep? There is one switch for that. The switch at the top of the brake pedal to turn on the lights whenever the brake pedal isn't all the way released.
The brake light on the dash can be activated by one of 2 switches. One switch is on the proportioning valve. The other is on the emergency brake.

 

[RatDog8o8]

RatDog8o8,

On the newer, you do not need to bend the tang, unplug and turn in or out as needed and replug. You need to be a contortionist, double jointed and or have a cockpit creeper.

.....does Harbor Freight sell that cockpit creeper?

 

[Focker]

I'm confused. What lights are on?
The brake likes on the back of the jeep? There is one switch for that. The switch at the top of the brake pedal to turn on the lights whenever the brake pedal isn't all the way released.
The brake light on the dash can be activated by one of 2 switches. One switch is on the proportioning valve. The other is on the emergency brake.

Not on a '71, there are 2 in-line hydraulic brake switches.

Today I noticed the switch in question is leaking brake fluid. I think it's a bad switch after all. I'll confirm by swapping the rear switch. This would be a great solution vs chasing down the other possible causes.

 

[GARGOYLEJEEPER]

RatDog8o8,
Nobody sells a cockpit creeper, must make one by modifying a regular creeper with a adjustable extension leg. So you can lay down while working under the dash, I had one but someone wanted it more than me and it walked off.

Focker,
That was the second thing to do after making sure it wasn`t electrical, go thru the system that was failing, which was the front, which you start at the switch.

Some people are confusing this system with the newer mechanical/electric system. All older systems are hydraulic/electrical.

 

[BusaDave9]

I'm still confused but slightly less so than yesterday. The original post says "the brake lights were on". That made me think we were talking about the brake lights in the tail lights.
Now everyone is talking about the hydraulic switches. Those switches would turn on the singular "brake" light on the dash.
Let me ask one more time, what light or lights are on?

 

[Focker]

Both rear brake lights... There is no dash light for this brake system.

 

[Hedgehog]

I had a Harley that had a hydrolic brake switch go out in the same way, it would stick and it leaked fluid. My advice is, replace both hydrolic switches and be done with it.