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Brake and ABS light on and soft brake pedal

65K views 14 replies 9 participants last post by  2000SLT4.7 
#1 ·
My daughter has a 2001 Dakota. Yesterday her brake light and ABS light came on. The pedal seems to be going down further than it should. I checked the brake fluid, it was fine and I couldn't find any leaks. Any ideas where to start now?

Thanks
 
#2 · (Edited)
If the brake and ABS lights are both on, you have a tiny leak somewhere in
the brake line. I had that symptom before mine split on me..twice..once
on a down ramp off the expressway, the pedal went down almost to the
floor and the brake/abs light came on. The fluid in the master cylinder
reservoir dumped out. I managed to crawl into a side street garage in
first gear with NO brake pedal pressure left. The master cylinder reservoir
emptied out when that happened. I was surprised that this could happen.
Had to replace the front to rear brake line and the lines over the axle and
the rubber hose over the axle as well as the two wheel cylinder. It
was a costly repair!

This year I started to get a low brake pedal and in April, one of the
front lines split and dumped out the fluid. Had to replace the front steel
brake lines and the rubber hoses to each caliper. Another costly brake
job because I decided tor replace the master cylinder as well.

Brake fluid absorbs moisture from condensation within the lines. The brake
lines rot out from within or from the outside, you can't tell when that
happens.

A defective master cylinder can cause a low pedal, but usually after
a couple of pumps, the pedal height is back. If you have a low
pedal and both the brake and abs light is on..

1. Proportioning valve next to the master cylinder is detecting low pressure
in either the two front lines or the rear line and actuating the BRAKE LIGHT

2. At the same time, the abs controller gets a signal from the PCM that there
is a brake problem (usually the rear lines) but you can have a abs light
on by itself just from the VSS sensor in the differential being bad...
BUT NOT BOTH...if BOTH the ABS and Brake light is on..one of the lines
after the proportioning valve has a slow leak, or losing enough line pressure
to activate the BRAKE LIGHT SWITCH on the proportioning valve.

DO NOT IGNORE THIS SYMPTOM!..there is a leak somewhere. Have the braking system checked out by a qualified brake specialist or mechanic...because it WILL fail when she hits the brake pedal at some point!
WARNING TO ALL DAKOTA OWNERS!
The master cylinder reservoir used on the Dakota is not a true isolated
dual braking system. IF A LINE RUPTURES, at the most you have about
two applications of the brake pedal before ALL THE FLUID IN THE RESERVOIR
IS LOST and air can get into the other brake lines!

READ MY STORY ABOUT MY BRAKE PROBLEMS EXPERIENCED ON MY 1998 DAKOTA
IN 2011 AND 2012, in this forum. Here is the link to my experience with a low
brake pedal. It is under 2ND generation Dakota 1997-2004 ; Wheels, Tires and Brakes"
and titled "Dakota braking system.well this sucks! " Part 1: Rear line blew out on me
and Part 2: Front line blew out on me a few months later.

http://www.dakotaforumz.com/showthread.php?t=1196

(There should be a class action law suit against Chrysler
for putting owners at risk for not using stainless steel brake lines!):rolleyes:
 
#4 · (Edited)
I can't see how the rear shoes (2001 still has brake drums) being a bit out
of adjustment would bring on both an ABS and Brake light with a low pedal.

The front calipers are self adjusting and that would provide a reasonably
firm pedal even if the rear shoes were a bit out of adjustment..however,
stranger things have happened, I suppose.

The rear brake shoes would have to had quite a bit of wear and possibly the adjusters were frozen, but if that was the case, backing up a few times and tapping the brakes wouldn't necessarily adjust the rear shoes, unless the drums were pulled and the adjusters were freed up and lubricated.

I think there is still an underlying brake issue there, but if the lights are
out..and it the pedal is back up, the symptom is gone..
(well at least for now)
. But a thorough brake inspection of all 4 wheels may be in order. I think I would be concerned if those same lights came on again on my truck.

ABS light coming on by itself is either the VSS sensor in the differential
or a fault with the ABS rear braking system itself.

A Brake light coming on by itself can be a parking brake not released or still stuck on because of sticking parking brake cable and maybe by backing up, that released the brake light., OR
the proportional valve (next to the master cylinder) has detected
a low pressure in one of the brake lines.

However, if an ABS and the Brake lamp BOTH came on at the same time,
AND
the parking brake was not engaged at the time..it probably needs to be investigated, even if backing up has cleared it.
 
#5 · (Edited)
I have the same problem with the two lights and soft pedal, so sence
My dak is t my daily driver I desided to check every thing that could
Fail, checked all wheel cylinders, all dry, checked all lines.
No leaks..my gut was telling me it was under the hood, turns out I have
A busted rubber plunger in the control valve....and now I need to find
a replacement....asked a mechanic and he said that if that seal is busted
It will cause an unbalanced pressure wich will cause the same simptoms but
With no leaks visible...you do have to remove the valve to get to this seal unfortunatly..
So for now in order to have it inspected ill have to bypas the rwal valve all together
Until I can fix/replace it...if you don't have any visible leaks this definatly a possible
Cause...and yes if I pump the pedal it firms up and the lights go out until
I press the pedal again....
 
#6 · (Edited)
I have the same problem with the two lights and soft pedal, so since My dak is my daily driver I decided to check every thing that could fail,
Checked all wheel cylinders, all dry, checked all lines. No leaks.

My gut was telling me it was under the hood, turns out I have
a busted rubber plunger in the control valve....and now I need to find
a replacement....asked a mechanic and he said that if that seal is busted
It will cause an unbalanced pressure wich will cause the same simptoms but
With no leaks visible...you do have to remove the valve to get to this seal unfortunately...
Well sometimes you can't always trust your gut completely.
Proper diagnosis of all braking systems is required and on the Dakota that
can be more difficult because of the RWAL (ABS).

Are you referring to the master cylinder? It has two valves and pistons,one for the rear and one for the front with rubber seals. If the seals develop problems
you can have a soft pedal until you pump it a few times, as the defective
seal causes the pressure in the lines to be released, especially if it is
sitting overnight.

So for now in order to have it inspected I'll have to bypass the rwal valve all together until I can fix/replace it.. If you don't have any visible leaks this definately a possible cause...
and yes if I pump the pedal it firms up and the lights go out until I press the pedal again....
What is the RWAL valve you are referring to?

Is it the HCU (Hydraulic Control Unit) with the
isolation solenoid and dump solenoid, which causes the fluid pressure to
the rear cylinders to be modulated? This is controlled by the ABS controller
and detects when the rear drums lockup via the VSS speed sensor.

The brakes will still work with the ABS light on, just that it's a warning
that something is wrong with the pressure in one of the lines.

It mifgr be:
Master cylinder itself that needs replacing
or
Proportioning valve
or
the HCU unit

In my case it was the Master Cylinder that cause the soft pedal to go
down almost to the floor after sitting overnight...but I never got
a brake or ABS light coming on, until one of the brake lines split.
I replaced the MC along with front brake lines this year. I replaced
the rear brake line when it split last year, along with new wheel cylinders
and rubber hoses. Brake lines can rot out from inside, due to moisture
in the lines causing the lines to rust outwards.

The ABS and the Proportioning valve add a lot more complexity to the
Dakota braking system, and it has to be checked out more thoroughly
from time to time. The ABS light coming on can also be a warning that
the VSS speed sensor in the Differential is not sending correct signals
as well. Usually you will get a speedometer malfunction when the speed
sensor is bad. Not good to multiplex too many functions on one sensor,
but this is the way Dodge does it...unfortunately. :D
 
#8 ·
I've had my '99 since Feb. 2011 & bought it with both lights on. I've never had a soft pedal or any kind of a leak. I replaced the shoes & pads last year & only had to add a little brake fluid. I haven't had to add any yet.:confused: I tried tapping the brakes in reverse but the lights are still on.
 
#9 ·
97 Dakota - intermittent soft brake pedal - no lights

Hi: Master cyl replaced twice because of intermittent soft pedal (ISP) after first replacement. ISP continues after second master cyl. I have no lights.
Pedal pumps up and stays up for a while, but at unpredictable times, it almost goes to the floor and pedal has to be pumped up again. No pattern. Good fluid level and no apparent leaks. Brakes have been bled several times. I am thinking it is an ABS valve/sensor, and new units are not available. I am thinking of bypassing the one unit with just two brake line connections to see if that fixes it. If it does, OK. If it doesn't, I'll bypass the bigger unit with 4 connections too because I am thinking that reinserting the first unit by itself is not a good idea. Cars ran well without ABS years ago. Bypassing the ABS is the plan, unless: does anyone know any other component that could cause the ISP without lights?
Are there any other factors I should know before I do this? Thank you for any ideas/comments/help on this problem. Steve
 
#10 ·
97 Dakota - intermittent soft brake pedal -

Truck is fixed. ABS had nothing to do with the problem. Rare event: prob was right front disc brake pad was unglued from plate and was worn down to 1/2 length so when brakes were applied it shifted position -- causing the plate to bend to the rotor and a soft pedal. Other times, the pad would move to the center of the plate so when brake applied, brakes would be normal. Mech for 30 years had never seen such a failure - defective brake pad where pad separated from mounting plate and was free to move around. New rotors, calipers and pads on both sides installed. Truck is good now. Beware the weird, intermittent symptom - no lights. Thanks for the forum.:)
 
#11 ·
I realize this thread is for the 2nd generation Dakotas, but I'm having a similar issue with my '91 Dakota. Yesterday morning on my way to work the emergency brake/brake warning light started coming on by itself, then would go out when I applied the brakes. It did the same thing going home and again this morning. The brake pedal feels normal, however the truck has a slight pull to the right when I hit the brakes. I haven't had a chance yet to check into the problem, but the first thing I'm going to look at is the front right caliper. But what I'm wondering; if the caliper is sticking, causing the pull to the right, would that also cause the brake warning light to come on? Or do I have two seperate issues? And a little history regarding the truck; the front brakes (rotors, calipers and pads, along with the wheel bearings) where replaced a little over two years ago and the rear brakes (shoes only) where replaced a little over a year ago. The truck gets driven less than 5,000 miles a year, so I feel confident that none of the brake components are worn out. Unless one of the rear wheel cylinders is leaking, but I would think I would notice that in the way of a soft brake pedal. And the truck doesn't have ABS.


Thanks!!!
 
#14 ·
abs and brake light on and brakes work but spongy

Hello, and Thank you for letting me join this sight, been on here a lot , just now joining. Here is my predicament.
Went out of town for 3 days, leaving truck sit on a pretty good incline, with nose going down incline. Upon returning jumped in truck, and headed to town, about a mile down road, ABS and Brake light came on, and brakes got a little spongy, by the time i got back home, brakes were awful spongy. Brakes needed replaced. Replaced front and rear brakes, Which upon passengers side E-Brake cable was broke. Replaced everything on rear except, wheel cylinders. Brakes not quite as spongy as before, but still not real good. Have checked for leaks, finding nothing, brake level in resorvoir never drops, any thoughts would be appreciated.
 
#15 ·
abs and brake light on and brakes work but spongy

Hello, and Thank you for letting me join this sight, been on here a lot , just now joining. Here is my predicament.
Went out of town for 3 days, leaving truck sit on a pretty good incline, with nose going down incline. Upon returning jumped in truck, and headed to town, about a mile down road, ABS and Brake light came on, and brakes got a little spongy, by the time i got back home, brakes were awful spongy. Brakes needed replaced. Replaced front and rear brakes, Which upon passengers side E-Brake cable was broke. Replaced everything on rear except, wheel cylinders. Brakes not quite as spongy as before, but still not real good. Have checked for leaks, finding nothing, brake level in resorvoir never drops, any thoughts would be appreciated.

I have a 2000 Dakota 2wd with positive traction, rear ABS and a 4.7 w/automatic transmission.
One day the Brake and ABS lights came on and the pedal started fading.
Nothing had been done to the vehicle.
There is a sensor on the differential, parking brake switch is fine and all pads/shoes are fine, no leaks, and the speedometer works fine. Added about a half cup of fluid (no level sensor on this vehicle), no change to the problem
So since the truck is 20 years old and the fluid was dirty, I replaced the master cylinder with a new one that I bench-bled before installation (as it was a little cruddy too) and bled all brake lines. Still no change
The shuttle valve switch for front/back brake line pressure loss was open (closed is bad), checked the switch and it works fine
There was nothing else I could check so I did a test. I bought a 3/16" (M10x1) bubble flair union (AGS #BLU-8C from any auto parts store) for about $4. I disconnected the lines from the ABS control unit, and put the union in place of it, bled the rear brakes and the pedal returned to normal and the lights went out. So the ABS unit was the problem source.
BTW, I had called the Dodge/Ram dealer and they would not even look at it saying they probably could not get parts for it anyway.
As far as the problem, the ABS unit is the most likely suspect, as far as a fix, that is up to you. Good luck!
 
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