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Brake warning light.


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Mine is constantly on till I hit a rough road, or vice versa. Anyway, Ive checked my lines, tons of pressure, rebled the brakes just for good measure.

 

What is it? its driving me insane. Just to test, I slammed on the brakes at 60 and came to a nice slam-dead stop in about 10 yards and its still on.

 

loose connection maybe?

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That light indicates your parking brake is engaged, not the functioning of your brakes, but it sounds like it's a short or loose connection somewhere. Track the wiring from the parking brake and check for loose connections or frayed insulation, these are the hardest to find unless really obvious. I had a similar issue with my fuel pump, when I slammed the door it would/would not work and I found a loose connection right by the parking brake, coincidentally.

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That light indicates your parking brake is engaged, not the functioning of your brakes, but it sounds like it's a short or loose connection somewhere. Track the wiring from the parking brake and check for loose connections or frayed insulation, these are the hardest to find unless really obvious. I had a similar issue with my fuel pump, when I slammed the door it would/would not work and I found a loose connection right by the parking brake, coincidentally.

 

actually my brake light came on in my 89 and my bro was drivign, he pulled over and the rear-brakes side of the MC was EMPTY... it senses pressure in the system.

 

but it does work with my e-brake too. however when that happened the e-brake on/off made no difference.

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...and it only comes on if there is a problem with the rear brake system.

 

Ill trace the lines when I get a change, probably tomorrow in shop class.

 

mine was a faulty wheelcylinder on the left side, but it leask really slowly so i still havent replaced it... brake light went off after about a week of driving without bleeding it, just added fluid. (leakybrakes=auto-bleeder system :nuts: )

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That light indicates your parking brake is engaged, not the functioning of your brakes, but it sounds like it's a short or loose connection somewhere. Track the wiring from the parking brake and check for loose connections or frayed insulation, these are the hardest to find unless really obvious. I had a similar issue with my fuel pump, when I slammed the door it would/would not work and I found a loose connection right by the parking brake, coincidentally.

 

actually my brake light came on in my 89 and my bro was drivign, he pulled over and the rear-brakes side of the MC was EMPTY... it senses pressure in the system.

 

but it does work with my e-brake too. however when that happened the e-brake on/off made no difference.

My mistake, I've had leaking brake cylinders and very low fluid in my master cylinder with no brake light warning so I didn't think it was prognostic.

 

...and it only comes on if there is a problem with the rear brake system.

I just checked the FSM and it says “the light is used to alert the driver if a pressure differential exists between the front and rear hydraulic systems.” Does this indicate a problem with your combination proportioning valve/brake switch? The FSM also says this part is not serviceable.

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In the case of my 1988 there is only one light for both conditions.

 

Light is on when you apply park brake or when you do not have the same brake fluid pressure on both circuits. For this, there is a switch in the brake pump.

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In the case of my 1988 there is only one light for both conditions.

 

Light is on when you apply park brake or when you do not have the same brake fluid pressure on both circuits. For this, there is a switch in the brake pump.

 

same here.

 

I'm going to try to unplug the sensor on my splitter block. if the light goes off, then I know somethings up re: my brakes (I'm about to go under it and check for line leaks and such) but if it stays on, then its something else.

 

BTW: if I hit a bump, it flickers a bit then goes out, hit anothe bump and back it comes.

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In the case of my 1988 there is only one light for both conditions.

 

Light is on when you apply park brake or when you do not have the same brake fluid pressure on both circuits. For this, there is a switch in the brake pump.

 

same here.

 

I'm going to try to unplug the sensor on my splitter block. if the light goes off, then I know somethings up re: my brakes (I'm about to go under it and check for line leaks and such) but if it stays on, then its something else.

 

BTW: if I hit a bump, it flickers a bit then goes out, hit anothe bump and back it comes.

 

It sounds like it's the parking brake pedal switch causing your problem. The parking brake might not be fully disengaged or the pedal is hanging down a little bit causing the light to be on as if the brake is on. Try pulling up on the parking brake pedal with your hand when the light is on and see if it goes out. If it doesn't go out also try pulling the parking brake release and pulling up on the pedal at the same time just incase the pedal is still on one click or so which won't allow you to pull it up and see if the light goes out then. Hope this info helps.

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i think its just a poorly wired system.

the whole truck is a poorly wired system, add to it 20 years of age and these things are an electrical nightmare.

I'm drawing up plans to graft in a late model PDC and rewire the critical components with heavier guage wire.

The single best improvement to my trucks electrical system was to add more grounds from the battery to the body, and the motor to the body.

everything works better.

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the whole truck is a poorly wired system, add to it 20 years of age and these things are an electrical nightmare.

 

Think the MJ is bad, you should help me work on the electrical system in my Australian built Capri sure can tell it's a britsh system :cheers:

 

Charles

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hrm. I parked at the store tonite, set the ebrake. truck was out of gear and off. I rolled back..! The pedal was right to the floor, like majorly to the floor.

 

yet, if I jack the truck up, and have someone lightly touch the brakes, the backs lock right away. I accidentally drove about a 1/16 of a mile with the ebrake on the other night, this problem only started happening today? its weird. I'm going to adjust the ebrake tomorrow and see what I get out of it. oh my light finally went off. I poked around under the dash looking for loose wires. but found an even more interesting problem

 

 

Antifreeze running down the firewall on the passenger side..!! I can't find where the hell it came from, I'm still nice and full of AF. wtf is going on? I didn;t have any in the cab either.

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i accidently drove with the e-brake on about a mile once, it worked well before that happened.

 

hasnt worked since. it holds on tiny little inclines.. but other places i park it in gear and when that fails i use parking chocks.

 

ok, get this... now it works?

 

before I left work, I had another Jeeper (stroked XJ) push me witht he MJ outta gear, with just the ebrake... rears skidded along the pavement... its beginning to piss me off, but I'm going to make some parking chocks tomorrow in shop class.

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Rob are you aware that the rear drum brakes are what used to be called "servo assisted," and that by design they work much better going forward than they do in reverse? That's a big part of the reason one shoe is longer than the other, and why it's important not to mix up the long shoe and the short shoe.

 

Parking brakes that are properly adjusted often don't hold worth patooties if you park heading uphill on a moderately steep slope. Ain't no way around it, it's the nature of the beast.

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soooo if we park facing DOWN the hill it should hold better? am i correct in assuming this? cause in some places parking in 1st with e-brake facing up hill it won't hold i have to chock it.

 

 

Put it in 4Lo.

 

no front d/s it doesnt shift well. not that it won't do it.. but the front yoke is suposed to be spinning for it to happen properly.

 

ADDITION: and doesnt that mean that my clutch is slipping? it wasnt THAT big of a hill.. that scares me. i don't wanna replace that anytime soon.

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