Brake help needed - JeepForum.com
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post #1 of 28 Old 06-09-2021, 08:39 AM Thread Starter
Hofmann419
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Brake help needed

Hello, I did a bunch of work on my brakes and now the red parking brake light on the dash is on. Trying to figure out whats going on. I've been troubleshooting it for a few days with no luck. From what I have read, that light only receives input from the parking brake switch and the level sensor in the master cylinder. Looking for some troubleshooting help.
Thanks, Herb.

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post #2 of 28 Old 06-09-2021, 01:22 PM
UKXJ
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That's right so either the fluid's low, the e-brake's not released, the switch under the e-brake lever's stuck on, the float in the MC reservoir's sunk or that switch has failed. Obviously, being a WJ there's the spectre of an electrical fault but, to my mind, prime suspect is the e-brake switch. However, 1st check all your brake work at the rear for anything that could affect either of those systems particularly if that included the e-brake, or even removing the rotor.
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post #3 of 28 Old 06-09-2021, 02:30 PM
HampshireWJ
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I had two ABS sensors go down and as well as the ABS warning light on I was getting red brake light on too. Changed out the ABS sensors and all was good again.
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post #4 of 28 Old 06-09-2021, 10:30 PM Thread Starter
Hofmann419
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Hello, I've checked the e-brake switch at the handle. When the handle is down, it contacts the switch and pushes the metal tab away from the other contact on the switch. The master cylinder is full and been changed twice. I suspect wiring, but I'm having a hard time finding a good schematic to follow. I have found a parking brake switch schematic and it looks like its a single wire straight to the light. No stops at a module or relay. I can't find anything on the level switch. There are no abs faults.
Here is the work I did. All new brake lines, all new hoses, new master cylinder and all new pads calipers and rotors. The light wasn't coming on before I did this work. I was hoping someone knew of any common problems or known wiring issues before I start chasing wires.

Thanks.
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post #5 of 28 Old 06-10-2021, 02:13 AM
Delta0
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Quote:
Originally Posted by Hofmann419 View Post
Hello, I've checked the e-brake switch at the handle. When the handle is down, it contacts the switch and pushes the metal tab away from the other contact on the switch. The master cylinder is full and been changed twice. I suspect wiring, but I'm having a hard time finding a good schematic to follow. I have found a parking brake switch schematic and it looks like its a single wire straight to the light. No stops at a module or relay. I can't find anything on the level switch. There are no abs faults.
Here is the work I did. All new brake lines, all new hoses, new master cylinder and all new pads calipers and rotors. The light wasn't coming on before I did this work. I was hoping someone knew of any common problems or known wiring issues before I start chasing wires.

Thanks.
Have you tried operating the parking brake switch by hand whilst someone watches the light.
Maybe flirting a bit of lubricant at it?

Have you cleaned the grounds involved?

Have you disconnected and reconnected the connectors involved?

From the Manual, P204

DIAGNOSIS AND TESTING - PARKING BRAKE
NOTE: Parking brake adjustment is controlled by an
automatic cable tensioner and does not require
adjustment. The only adjustment that may be necessary would be to the park brake shoes if they are worn.
The parking brake switch is in circuit with the red
warning lamp in the dash. The switch will cause the
lamp to illuminate only when the parking brakes are
applied. If the lamp remains on after parking brake
release, the switch or wires are faulty.
If the red lamp comes on a fault has occurred in
the front or rear brake hydraulic system.
If the red warning lamp and yellow warning lamp
come on, the electronic brake distribution may be at
fault.
In most cases, the actual cause of an improperly
functioning parking brake (too loose/too tight/won’t
hold), can be traced to a parking brake component.
NOTE: The leading cause of improper parking brake
operation, is excessive clearance between the parking brake shoes and the shoe braking surface.
Excessive clearance is a result of lining and/or
drum wear, drum surface machined oversize.
Excessive parking brake lever travel (sometimes
described as a loose lever or too loose condition), is
the result of worn brake shoes, improper brake shoe
adjustment, or improperly assembled brake parts.
A too loose condition can also be caused by inoperative or improperly assembled parking brake shoe
parts.
A condition where the parking brakes do not hold,
will most probably be due to a wheel brake component.
Items to look for when diagnosing a parking brake
problem, are:
• Brake shoe wear
• Drum surface (in rear rotor) machined oversize
• Front cable not secured to lever
• Rear cable not attached to actuator
• Rear cable seized
• Parking brake lever not seated
• Parking brake lever bind
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post #6 of 28 Old 06-10-2021, 11:01 PM Thread Starter
Hofmann419
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Hello, I've actuated the parking brake switch and viewed the light on the dash myself. The switch is a very simple design. It is a metal spring tab that has one wire going to it. When the handle is down, it pushes down on the tab, pushing it away from the metal switch, thus breaking the circuit. When the handle is raised, the spring tab springs up and contacts the switch and compleats the circuit and illuminates the red brake light on the dash. The rest of that manual deals with parking brake operational problems. One sentance of that manual did interest me. It states that the red brake light also comes on if there is a fwd or rear hydraulic issue. Heat, how and where in the hydraulic circuit does it detect this problem.
Thanks,
Herb.
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post #7 of 28 Old 06-10-2021, 11:43 PM
HampshireWJ
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Here's an extract from the manual. I think if you are happy the handbrake lever is not your problem then you need to look elsewhere - have you tested this the old way with crocodile clips and a bulb? What made you do the brake work in the first instance and what did you actually do? - these details will likely help with providing a solution. I recall reading quite a lot about bleeding the brakes and ensuring you didn't get air in the ABS control module.

OPERATION
The lamp is turned on momentarily when the ignition switch is turn to the on position. This is a self
test to verify the lamp is operational.
The red warning light alerts the driver if the fluid
level is low or the parking brakes are applied. A red
warning lamp with an amber warning lamp may
indicate a electronic brake distribution fault.
DIAGNOSIS AND TESTING - RED BRAKE
WARNING LAMP
The red warning lamp illuminates when the parking brake is applied or when the fluid level in the
master cylinder is low. It will also illuminate at start
up as part of a bulb check.
If the light comes on, first verify that the parking
brakes are fully released. Then check pedal action
and fluid level. If a problem is confirmed, inspect the
brake hydraulic system for leaks.
A red warning lamp with a amber warning lamp
may indicate a electronic brake distribution fault.
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post #8 of 28 Old 06-11-2021, 12:55 AM
Delta0
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Quote:
Originally Posted by HampshireWJ View Post
Here's an extract from the manual. I think if you are happy the handbrake lever is not your problem then you need to look elsewhere - have you tested this the old way with crocodile clips and a bulb? What made you do the brake work in the first instance and what did you actually do? - these details will likely help with providing a solution. I recall reading quite a lot about bleeding the brakes and ensuring you didn't get air in the ABS control module.

I cocked up recently whilst bleeding WJ brakes.
I blew air through the ABS and out through the FOS nipple.
I blew brake juice through that circuit.
My brakes are tickety boo.


OPERATION
The lamp is turned on momentarily when the ignition switch is turn to the on position. This is a self
test to verify the lamp is operational.
The red warning light alerts the driver if the fluid
level is low or the parking brakes are applied. A red
warning lamp with an amber warning lamp may
indicate a electronic brake distribution fault.
DIAGNOSIS AND TESTING - RED BRAKE
WARNING LAMP
The red warning lamp illuminates when the parking brake is applied or when the fluid level in the
master cylinder is low. It will also illuminate at start
up as part of a bulb check.
If the light comes on, first verify that the parking
brakes are fully released. Then check pedal action
and fluid level. If a problem is confirmed, inspect the
brake hydraulic system for leaks.
A red warning lamp with a amber warning lamp
may indicate a electronic brake distribution fault.
See above
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post #9 of 28 Old 06-11-2021, 08:00 AM Thread Starter
Hofmann419
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Hello, yes I am fairly confident that the parking brake system is not the issue. The reason I did the work is because the long solid brake line was rusted and leaking. So I replaced every solid brake line with stainless lines. I figured, since I'm doing work anyway, I also replaced every soft brake line, master cylinder, and all pads calipers and rotors. The red light was not on before I started the work, so its safe to say I induced it. I have bled the brakes at least ten times, thinking it was a bleeding issue. After I bled it bunch, I figured the level sensor in the new master cylinder was bad, so I replaced the master cylinder again. Its possible there is air in the abs since the whole system was dry, but I would think that it would be out by now with all the bleeding I did. Unless there is a different bleeding procedure. And how would the red light sense that unless it gets input from it somehow. Also, the breaks work great with no leaks. I put about 200 miles on the car.

Thanks.
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post #10 of 28 Old 06-11-2021, 08:34 AM
2oldjeeps
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i learned to live with beeps,red lights for abs and airbags.
i watch oil and temp...and gas,,,

99wj, 150,000 miles
00xj ,189,000 miles
10hummer3,76,000 miles
98xj, 133,000 miles
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post #11 of 28 Old 06-11-2021, 09:11 AM Thread Starter
Hofmann419
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Yes, unfortunately it will not pass state vehicle safety inspection with the brake light on. I cannot renew my tags until it passes inspection.
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post #12 of 28 Old 06-11-2021, 09:27 AM
HampshireWJ
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There is quite a bit written within this forum about bleeding your master cylinder correctly and the very real possibility of inducing air into the ABS Controller. If you have/can borrow a scanner that bleeds the controller that would be a good starting point - it is possible to 'redneck it by jumping on the brakes a few times on a gravel surface - in fairness this sounds more fun. Some links from this forum here - https://www.jeepforum.com/forum/gtse...yinder%20bleed .

I have a sneaking suspicion that your problem lies in the master cylinder or/and your ABS controller. In some ways it is good you have induced the problem and not inherited it from someone. As the brakes work well in normal circumstances I am leaning toward it being air in the ABS controller, if it were air in the master cylinder i reckon the brakes would not be so good. The ABS unit only comes into play when it thinks the brakes are locking up and tries to stop it - well that's my understanding.

I reckon this thread may run a while. Good luck.
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post #13 of 28 Old 06-11-2021, 09:43 AM
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Your master cylinder float is sunk. It probably got stuck when you added brake fluid while bleeding the brakes after the repairs. Reach in and pry it up with a small dental pick or something similar. this usually happens when the master cylinder gets gummed up.

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post #14 of 28 Old 06-11-2021, 09:46 AM Thread Starter
Hofmann419
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Yes, I thought so too. I have a scan tool. I ran the abs bleed twice. Light is still on. I'm getting the abs code #50 brake fluid level switch fault. And it won't clear when I press clear codes. I guess I can start checking the switch wiring. Trying to find a good schematic. I don't see how I could have induced a wiring fault but stuff happens. I have replaced the master cylinder twice so I doubt its the switch itself, but I could be that lucky guy. I guess I'm chasing wires. At least its only 96 degrees outside.
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post #15 of 28 Old 06-11-2021, 09:47 AM Thread Starter
Hofmann419
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The float is sunk on two new master cylinders? I guess I could be that lucky.
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