help, ebrake light came on

[89armyxj]

Hey guys quick question. My ebrake light came on hile braking today. First time ive seen this pop up. I am checking brake fluid, the back side is almost full the front resevoir is empty. Is this normal or should the front part be full as well? Also any other ideas as to why the light came on? Pads maybe? Any help would be great. Thx. 89 xj base

 

[groovyjeepster]

Sounds like you have a leak. Check your lines. The light not only is an indicator for your ebrake but also comes on to warn you that you are losing pressure in your system.

 

[89armyxj]

Do both the front and back portion of the brake resevoir need to be full?. Right now only the baxk part is full.

 

[groovyjeepster]

Yes both sides need to be filled. Fill it up and check for leaks in the lines and the calipers and in the wheel cylinders.

 

[wheeling365]

The way most systems are designed is that the proporting valve has a switch in it. It operates off of pressure in the system. If one side of the system starts to leak the pressure on the switch is not equal. The switch will activate the light in the dash until the leak is fixed.

I'm not sure how the older XJ's are setup brake plumbing wise. Some cars are LF and RR, RF and LR so that if the system were to fail it still stops evenly with reduced breaking power on the non leaking side.

Even with the leak repaired you may have to look up the bleeding procedure to equalize the system pressure again to get the light to go out.

If you can't find a leak anywhere else try unbolting the master cylinder from the booster and inspect the back of it for a leak. I've seen them leak there and fill the booster with fluid. Once enough gets into it the fluid will either get sucked into the intake by the vaccum hose or run down the inside of the firewall.

You may also want to use this as a good excuse to flush the old fluid out. Brake fluid is hygroscopic. It abosrbs moisture which lowers it boiling point and also rots lines from inside over time.

 

[joe_peters]

The two reservoirs in the MC:

The large reservoir is for the front disc brakes--the pistons in the calipers are large and it requires more fluid.

The small reservoir is for the rear brakes--little wheel cylinders require less fluid to move them.

You most likely have one or more rear wheel cylinders leaking.

When the pressure in the system becomes unbalanced, the pressure differential valve moves in the proportioning valve and trips the light on your dash.

Repair the rear brakes--i.e., replace the wheel cylinders, might as well do both even if only one is leaking, replace the shoes if they are contaminated or worn. Inspect the drums.

Good luck.

 

[lawsoncl]

Am I the only one thinking that if he doesn't know that both reservoirs are supposed to have fluid, that he might need a bit more help than the good advice we've provided?

It's going to be a little bit more work than just finding the leak. You're going to have to replace whatever is leaking and the shoes if contaminated. You should replace both sides at the same time. Then begins the fun of bleeding the system.