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Unread 01-31-2009, 05:04 PM   #1
wm69
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Join Date: Jun 2003
Posts: 3,138
Brake light on dash is on

I had a YJ PB master and booster put on my hunting rig a couple of years ago. The brake pedal has way too much travel before the brakes engage, but other than that they seem to work ok.

Today I was driving the Jeep and the brake light on the dash came on. I pumped the brakes and as I did so the light would flicker, or sometimes even go out, but would come back on when I stopped pumping.

Brakes seem to work about the same as before (I've planned on doing an adjustable push rod, but this is my hunting rig so I don't get a lot of time to work on it). Fluid is full.

Anyone got any suggestions on where to look?

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85 CJ7 258, borla header, Team Rush, MC2100 ,optima batt, Warn 8274, agr super box 2 & pump, T5 w/ B&M shifter, centerforce 2, superior 1 piece axles, warn hubs 2.5 in lift, 31" BFG MT

85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO
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Unread 01-31-2009, 05:21 PM   #2
thantos858
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1974 CJ5 
 
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Check the fluid for air bubbles. I would also check all the electrical connections for the brakes might be as simple as a lose connection.
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Unread 01-31-2009, 09:40 PM   #3
wm69
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well, I looked around the MC for any wires that would be a low pressure switch or something similar, and didn't see any. There has to be a sensor somewhere that makes that light come one somewhere. It was getting dark so I didn't crawl up under the Jeep.
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85 CJ7 258, borla header, Team Rush, MC2100 ,optima batt, Warn 8274, agr super box 2 & pump, T5 w/ B&M shifter, centerforce 2, superior 1 piece axles, warn hubs 2.5 in lift, 31" BFG MT

85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO
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Unread 01-31-2009, 10:29 PM   #4
illinicj
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1979 CJ7 
 
Join Date: Nov 2007
Location: Lake Zurich, IL
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There is an electrical switch in the proportioning valve. That is probably what is triggering your dash light.
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Unread 02-02-2009, 11:32 AM   #5
tamu83cj
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1983 CJ7 
 
Join Date: Mar 2005
Location: Houston, TX
Posts: 177
The switch is in the hardest to get to place...on the inside of the frame just behind the engine compartment on the driver side. Follow the brake lines out of the engine compartment and look for a coiled area, it will look like the coils coming off the MC. There is a small plug/sensor attached there.

My parking brake light wouldn't go off, so i unplugged mine. I don't plan to replace the plug because it is so hard to get to unless you can get the jeep way up in the air.

Does anyone know how i can check the fluid for air pockets, and what i will need to do if there is air in the lines? AKA, how do i bleed the lines? thanks,
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Unread 02-02-2009, 03:13 PM   #6
wm69
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I'll check it next time I'm down there. It might just need to be bled again.

At this point I've seriously considered yanking the whole PB assembly off of the thing and switching to manual brakes. First I had the factory CJ setup, which came on the Jeep, but then couldn't find a new (not reman) booster and MC, so I got a reman, which didn't work, so I got another reman, which didn't work, so then I got a YJ setup, which had a bad MC, so I bought a new YJ MC, and it works, but the brake pedal almost goes all teh way to the floor before the brakes engage, so now I've been planning on pulling it all off and making the push rod adjustable to get the pedal right, and now the freaking brake light comes on.

We have two other Jeeps with normal, non power brakes, and they are so much easier to deal with.
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85 CJ7 258, borla header, Team Rush, MC2100 ,optima batt, Warn 8274, agr super box 2 & pump, T5 w/ B&M shifter, centerforce 2, superior 1 piece axles, warn hubs 2.5 in lift, 31" BFG MT

85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO
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Unread 02-02-2009, 03:21 PM   #7
thantos858
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1974 CJ5 
 
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Tamu bleeding the lines just start with the furtherest away bleeder and pump the brakes until theres no more air but make sure you resivor is full.

I would just do the shortening the rod then see what it does should only take a couple hours.
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