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Dodge Dakota Braking Problems



  • srs_49srs_49 Posts: 1,394
    I thought the master/slave braking setup was right-front coupled to left-rear, and left-front coupled to right-rear. So that if you lost all braking in one path, you would still have one front and one rear brake working.

    Now, given that the Dakota (like most trucks), are very light in the rear end when unloaded, it might not be surprising that losing one of the braking paths might feel like you only have 25% braking.
  • carvermancarverman Posts: 101
    edited August 2011
    Well I am still annoyed with this one! as I barely avoided a rear ender, which
    would have placed me at fault. Ok, as far as I have been able to trace on
    my 1998 Dakota with the 318 V8,the brakes are configured as follows:

    Master cylinder reservoir has 2 separate for the back
    and one for the front. So below a certain brake fluid level, the compartments are separate there.
    The master cylinder has a dual piston (one for the front system and one for the back).

    The o/p of the master cylinder goes to a combination valve that has separate
    inputs and outputs.
    The lines are crossed going into the input of this combo-proportioning valve with the REAR of the master cylinder going to the FRONT of the combo valve, and the FRONT of the MC going to the REAR of the combo valve.

    The combo valve has a (two wire) fluid pressure switch fitted. so when the piston inside the combo valve moves from one side to the other, (due to more pressure on one side than the other, in case of a leak) the difference in pressure will activate the dash board BRAKE and ABS light.

    The combo valve has two output lines coming out of it.

    Combo valve: the FRONT line o/p goes to the HCU (hydraulic
    control unit) that is controlled by the ABS controller. The HCU has a dump
    valve solenoid and an isolation valve solenoid on it. The o/p of the HCU goes
    down to the distribution block (on the frame) and a line goes from there to BOTH rear wheels. There is a flexible line that goes to middle of the axle and two lines come off it to each rear wheel cylinder. These are the ABS controlled
    drum brakes. The front disc brakes are just normal brakes.

    Combo valve: The REAR o/p line goes down to a distribution block (on the frame) and then two lines go off from it, one to each front wheel.

    Since the only common place for fluid to be transferred between the front
    and rear braking systems is the Combination valve, the fluid loss had to
    be there, because the piston inside didn't move all the way(sticking?) and repeated brake pedal applications forced more fluid to be transferred from
    the front (disk brake) system over to the ABS controlled system..which had a split line LEAK on the front to back line.
  • I am stumped on this one and would appreciate any help figuring this out..
    2000 dakota 3.9l 4x4 standard transmission

    driving down the road one day the vss sensor went out: engine light on, no speedo, abs light on, brake light on but the brake wasn't on, shift light told me to shift into a higher gear when already in 5th. engine started stalling and backfiring. got it home, and replaced the sensor ($40).

    all is good, except now the brake pedal is soft, and pulsates a bit(but it doesn't feel like the normal pulsating from the normal warped rotor problems) it feels more like a clunking in the pedal if that makes any sense. checked all the rotors and pads and have new rear brakes(shoes and drums) nothing looks bad that way....and this only started after the vss sensor was replaced... what else should I look into?

    thanks in advance for any ideas :)
  • did you get this fixed? mines doing the same thing. changed the rear brake line which was the easiest.
  • carvermancarverman Posts: 101
    edited November 2011
    driving down the road one day the vss sensor went out: engine light on, no speedo, abs light on, brake light on but the brake wasn't on, shift light told me to shift into a higher gear when already in 5th. engine started stalling and backfiring. got it home, and replaced the sensor ($40). [/quote]

    The ABS controller WILL set the ABS light and Brake light if it detects
    a fluid leak/loss of braking pressure in the rear lines from the HCU (hydraulic control unit) which pulses the rear brakes, or loss of fluid pressure at the proportioning valve.
    So it sounds like you had some sort of brake issue already,
    but that shouldn't cause stalling and backfiring..that is something else
    The Vehicle speed sensor (in rear differential) sends pulses to the PCM
    for the Speedo and to the CAB (Controller Antilock Brake) for RWD antilock
    brakes. So if you have complete failure in the VSS, the PCM doesn't
    get the pulses and it can't calculate the vehicle speed. The CAB can't
    perform the ABS function, BUT you would still have regular braking power.

    On the Dakotas, the rear brakes are drum brakes and they use
    a RWAL (rear wheel anti-lock) system to prevent the rear drum brakes from locking up on you, causing a skid when you jam down on the power brakes hard.

    all is good, except now the brake pedal is soft, and pulsates a bit(but it doesn't feel like the normal pulsating from the normal warped rotor problems) it feels more like a clunking in the pedal if that makes any sense.
    checked all the rotors and pads and have new rear brakes(shoes and drums) nothing looks bad that way....and this only started after the vss sensor was replaced... what else should I look into? [/quote]

    The clunking is a mechanical issue with either the front calipers or the
    rear shoes. If the pedal feels soft and there is brake fluid in the reservoir
    up to the fill mark, then some possibilities are:

    - Master cylinder leaking and air is getting in the lines somehow.
    -one of the rear wheel cylinders is leaking fluid
    - pinhole leak in the front to rear long brake line somewhere.
    it needs to be checked thoroughly and the rubber line that connects
    it to the axle lines. That rubber line could be abraded from wearing
    on the axle and have a small pinhole leak

    -ABS system (rear brake line and wheel cylinders have possibly got some air in there somehow.

    -Front pads ok? If not, more fluid has to be transfered from the master
    cylinder to the caliper pistons to achieve front braking and the pedal
    WILL travel further to the floor to achieve braking power in that case.

    Solution: a) Check pads for wear, replace if necessary.
    b) bleed all 4 wheels at bleed screws on calipers/ wheel cylinders.
    If the new shoes/drums were replaced recently, was the wheel cylinders ever bled?

    That may be a challenge however, if the bleed screws
    are seized from brake heat over the years.

    c) Try resetting the CAB by disconnecting the positive battery cable for
    10 seconds. If the CAB still thinks there is a brake issue, it won't
    reset itself until the actual problem is cleared.
  • i did not bleed after installing the line. i didn't know air in the lines would cause the brakes to tighten up. i'll try bleeding but i can't see how air in the lines would cause the brakes to tighten up. unless it gets in the cab and screws it up. i'll try bleeding the only thing left is to change the cab unit. if this doesn't work i may by pass the unit and just run straight brake line to the rear.
  • The VSS in the rear diff was changed and stopped all the issues that resulted from it. I could stop normal (no soft pedal or clunking feeling)even when it was bad, no trouble with the brakes at all....but once it was changed, we took it for a test drive, and that's when the soft pedal and clunking feeling in the pedal showed up.

    Yes the rear brakes were bled when they were changed a month before all that went down, we had to change the one cylinder at that time, and the brake line to it as well. front pads and rotors still looked good as well. no loss of fluid either. Should I maybe try to bleed them again even tho all we did was change the vss sensor?

    I probably should say that my dashboard isn't light up like a christmas tree anymore, that was fixed with the new sensor also. no lights on at all. I still drive it, just not when there is a lot of traffic as I don't trust others to not pull out in front of me as I don't have much confidence in stopping quickly at the moment.

    thanks for the help ;)
  • carvermancarverman Posts: 101
    edited November 2011
    So you changed the line to the rear cylinders and both rear cylinders?

    That would introduce air into the braking system and it doesn't take much air to give
    you a soft pedal.
    I agree that the VSS sensor going bad and being changed has nothing to do with
    a soft pedal. It would only give you a ABS and BRAKE indicator coming on as well
    as a check engine, since the CAB requires the pulses coming in from the VSS to
    function. IF the brake lines and brakes are free of air, you would get a normal
    pedal feel and the hydraulic brakes would still function normally.

    The soft pedal means that air has entered the system somewhere, it can
    get in through the threads of the loose bleeder screw or the master cylinder
    sucking in air when the fluid is too low.

    Did you add fluid to the master cylinder and check it constantly while bleeding the rear
    brakes? When bleeding, you must not allow the brake fluid level to get down to the point
    where the master cylinder sucks in air...if it did, then there is now air trapped in the front calipers
    and they must be bled to get rid of the air in the front lines.

    When bleeding brakes, you need lots of brake fluid. You need a rubber tube fitting
    tight on the bleeder screw going into a container of brake fluid. The end of the
    rubber hose cannot be exposed to air..otherwise air will get in via the bleed screw
    as soon as the fluid stops flowing when the pedal is down. As soon as the pedal
    is released, the system starts sucking air wherever there is any tiny exposure to air.

    If one person bled the brakes, then there is some likelyhood that air did manage
    to get into the lines, and trapped inside the front calipers. If you didn't bleed the
    calipers, then there is a good possibility that there is some air in one or both
    of the front calipers which do 70% of the braking on the vehicle.

    With two people , one pumping the brake pedal and the other checking the master cylinder
    fluid level and operating the bleeder screw with a hose on the bleeder screw going into
    a sealed plastic bottle containing brake fluid, there would be less chance of getting
    air introduced back into the system.

    (Instructions to person pumping pedal)
    1. PUMP!
    2. HOLD (dont release pedal until instructed)
    Other person opens up bleeder screw and fluid and air go into a closed container
    3. Ok (RELEASE
    repeat the proces)s 6 to 7 times for each caliper/wheel cylinder
    NOTE: You will require 2-3 containers of brake fluid for this, Do not pour old
    fluid back into mastercylinder as it may contain moisture which will boil inside
    if the brakes get too hot!

    So to summarize: with one person pumping and holding the pedal down WITHOUT RELEASING,
    the other person operates the bleed screw and fluid/air released into a bottle
    containing some brake fluid.

    Here is a youtube video on a spongy pedal tough brake bleed job.
    Calipers incorrectly installed on this car. They ended up using
    the reverse bleeding method and note the last section where the caliper bleed screw was
    elevated to allow trapped air (still in the caliper) to finally make it's way out and allow
    for a firm pedal.
  • carvermancarverman Posts: 101
    edited November 2011
    See my reply (soft pedal rquires rebleeding of brakes) FRONT AND REAR!
  • Changed the passenger side brake cylinder when we did the brakes and the line to it. We bled them properly, and they worked just fine, no issues up until the VSS went bad a month later. We didn't touch any part of the brake system when we changed the VSS. But That is when the problem showed up. That is what has us confused.

    Tomorrow is supposed to be a pretty nice day here in NE Ohio, will try to bleed them tomorrow health permitting(my brother has some troubles)
    I will let you all know if your ideas help :) thanks!
  • My ABS and brake light have been coming on intermittantly. Speedometer is okay though. I took my 2000 Dakota in and had it scanned by a friend who works for a Goodyear repair center. He had codes 65, 52 and 51 stored. After erasing them the code 51 came back right away. He thought the code 51 could be causing the other two stored codes. I have Rear only Anti-lock brakes. Anyone have any suggestions on this situation? I think the code 51 relates to the relay which controls the solenoids.
  • carvermancarverman Posts: 101
    edited November 2011
    2nd gen Dakotas use the Kelsey-Hayes RWAL braking system on the
    rear drum brakes. The convential split master cylinder has two lines that
    go to the proportioning valve (which has the brake light PRESSURE switch),
    then it goes to the HCU (Hydraulic Control Unit) which has the ABS isolation
    solenoid and the ABS dump solenoid.

    CAB operates both solenoid valves on the HCU.

    The Normally open isolation valve blocks brake pressure from the Master
    cylinder during anti-lock braking and a Normally Closed dump solenoid
    valve is there to release pressure in the rear brake circuit when the
    anti-lock operation is initiated. This is done at a fast speed so the
    action of both valves basically "pumps" the brake fluid at a fast interval,
    preventing the Bendix type drum brakes from (at least in theory),
    locking up.

    On the RWAL Dakotas, the CAB (Controller Anti-lock Brake) receives a speed signal from the VSS in the differential, to determine whether to initiate anti-lock action if the VSS is no longer providing pulses.
    The speedometer is also driven (by the PCM) from pulses derived from
    the VSS.

    Code 65..main relay open (ABS) (open/shorted, poor electrical contact
    or even a faulty relay)
    Code 51 ..Rear isolation solenoid open
    Code 52 ..Rear dump solenoid open

    There can be internal CAB faults as well.

    Brake light warning indicator on:
    possible causes: (assuming no problem with dash indicator itself)
    - pressure switch in proportioning valve out of position
    (proporting valve issue or fluid leakage to rear brakes)
    - faulty CAB

    ABS indicator set (by CAB)
    (assuming here that the indicator itself does not have a problem.)
    open or short condition
    condition in hydraulic system/lines to rear brakes that needs to be
    checked out
    defective VSS sensor
    possibly a faulty CAB..try removing ABS fuse for 5 seconds or
    disconnect negative on battery and see if it clears first
  • Thanks for all the info! Not sure where to start. Noticed yesterday when I started my truck the lights didn't come on. Then later when I stopped and restarted the lights came back on. Not sure but it seems when it gets colder outside the lights come on more often. I thought the code 51 was in reference to the main relay. At least that is what my friend told me from Goodyear. I was thinking the relay is not making good contact and possibly causing the problems. Want to look closer at he relay itself and see if I can replace it.
  • ABS specific code 51 is REAR ISOLATION SOLENOID OPEN. this is applicable
    to Dodge has nothing to do with any kind of relay.

    Looking at the the 2000 wiring diagram for RWAL brakes, there is NO
    relay associated with the CAB. I checked the PDC on my 1998 Dakota
    and confirmed this,

    The CAB is fused by a 40amp fuse in the PDC. So obviously if the lights
    are coming on periodically, the CAB is getting battery power through that
    fuse to operate. It has it's own separate ground connections G101.

    There is also a 10amp fused ignition- run going to it. This would be coming
    from the ignition switch I believe.

    The rear wheel speed sensor comes into it and so does the CCD +/- data bus that it communcates with the PCM.

    The brake pressure switch has it's own separate ground and comes in from
    the proportioning valve. The CAB also senses the brake switch.

    The ABS specific codes (read from the ABS controller diagnostic connector)

    are: 21 to 90. Some are generic. Some are applicable to 4W ABS systems,
    some to RWAL (like the dakotas) and some to internal ABS controller issues.

    I don't have any specific wiring information on the K-H RWAL HCU..
    but this link will give you a pretty good idea of how it works on the Dakota.
  • The relay I was referring to is inside the CAB. I do have the shop manual for my 2000 Dakota but it doesn't give any detail on the CAB. If you are saying the code 51 is about the rear isolation solenoid being open, then I would assume it is sticking or has something inside it not allowing it to close completely. Do you know if this soleoind can be replaced seperatly or does the assembly have to be replaced. I reviewed the link on the RWAL and the codes they list do not show the codes I am getting. My shop manual does not list any codes in reference to the Anti lock system. Do you know where the list of codes can be found? Thanks again for your reply!
  • carvermancarverman Posts: 101
    edited November 2011
    I hate the editor on this site!
    I had an answer all typed up and lost it.

    Anyway, the K-H ABS control codes are NOT integrated with the OBDII diagnostic connector, as it was a proprietary RWAL ABS that most NA
    vehicle manufacturers use. To read the ABS codes, you need an expensive
    shop scan tool. ($2500). The CAB has it's own diagnostic connector for

    As far as the ABS codes..the link below will give you a explanation for
    each code once you enter the make,model, year and abs code.
    (ABS codes 21 to 89) - - - - - - ota&year=2000&code=51&confirm=1&submit.x=21&submit.y=23

    As far as I know the solenoid/valves on the K-H HCU are not individually
    replaceable, and these are pretty expensive units, so you would want
    to make sure that is what is faulty first.
  • The scanner that was used to pull the codes I've mentioned was a fairly expensive one. It belonged to the Goodyear service center I mentioned earlier. My friend plugged into the connector under the steering wheel to retrieve them and then cleared them. Right away the code 51 came back. I just didn't have a listing of all the codes, but he did tell me what they were with a description. I was trying to write them down as he read them to me. Thanks!
  • You can get a used ABS controller/HCU Pump for your 2000 Dak
    from these used parts places..they offer a 1 year guarantee..that's
    what I would do if it was mine. inventory.html
  • If it's showing up code 51 then the isolation solenoid and valve appear to
    be sticking or faulty. Probably some corrosion from moisture in the
    brake lines. This will occur over time if the brake fluid is not replaced
    periodically (every 2-3 years). Time to replace it I would think.

    I've never tried reading the ABS codes, because all I have is the elcheapo
    OBDII code reader and it doesn't pull the codes from the ABS controller
    like the more expensive shop scan tools. I'm not going to invest $2500
    for a more extensive set of tests, when I rarely have an ABS fault on mine.

    My only time was when the rear brake line failed this summer after 13years, and after replacing it and both wheel cylinders,
    bleeding the braking entire system, it's been fine No ABS or Brake indicator.
  • acb95acb95 Posts: 1
    hey i had the same problem with the 2 lights being on, check the brake fluid, its probly low, mine said low when the lights are on, then if you have the engine on, shut it off and start it back up and the lights should turn off
  • That's news to me. As far as I know the Dodge RWAL system does not
    have a brake fluid level sensor. It uses just a compartmentalized front/rear
    standard master cylinder used for many years with a dual braking system.

    The ABS controller senses only two inputs. Pulses from the the VSS sensor
    in the diff and a brake pressure switch located on the proportioning valve
    provide input to the ABS controller (CAB)

    If the rear wheels lock up, the differential is no longer turning and their
    will be no pulses coming into the CAB, so it starts to initiate ABS
    braking on the rear wheels for a RWAL system.

    If the VSS is no longer functioning and the ignition is still on,
    it may think that that is a wheel lockup if the vehicle is moving and continue with ABS. The speedometer not working or erratic would be another indication of a VSS problem.

    If there is a fluid loss in the front or rear brake system, the differential
    fluid pressure switch will activate and it will turn on the ABS and Brake

    Lifting the battery and resetting the controller only works if there are
    no faults present. If the brake pressure switch is still operated one
    way or another, signifying an open brake line somewhere, the
    ABS and Brake light will stay on until the braking system is repaired and
  • I checked the level and it is full! Don't want to overfill it.
  • carvermancarverman Posts: 101
    edited November 2011
    The level of brake fluid in master cylinder has nothing to do with your
    ABS/Brake indicators being on. As long as the fluid doesn't drop down
    inside the reservoir to the point that the master cylinder is sucking in air, the possible
    reasons for the ABS/BRAKE light coming on..could be:

    1. You have a pressure leak somewhere in one of the lines, or calipers
    or wheel cylinders

    2. Proportioning valve is stuck in one position?

    3. VSS sensor not providing adequate pulses to the CAB. If this was the
    case, the speedometer gets affected as well, since the same sensor
    is used to calculate Vehicle speed by the PCM.

    4. HCU (ABS pump) fault in either the isolation or dump solenoid valves.

    5. ABS controller itself..although this is much lower probability.
  • I haven't done anything yet to correct the problem of the ABS and brake light coming on. Yet with the warmer than normal weather we have had this winter it has helped me discover that when it is colder (around freezing temps) the lights come on more. Although when we had days when it was say around 50 degrees, I noticed that they did not light. I'm thinking it has something to do with the brake fluid viscosity? Not sure. I am thinking of replacing the brake fluid to see if it helps the situation. What do you think?
  • bugboy64bugboy64 Posts: 1
    edited February 2012
    ok i have a 2001 dakota quad cab at times the right rear brake locks up but no abs light on any suggestions ?
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    If only one brake is locking up, it could be a bad brake hose on that side. That's more common with a single front brake locking, but have the rear lines checked.

    kcram - Pickups/Wagons/Vans+Minivans Host
  • bevibevi Posts: 1
  • skoto1skoto1 Posts: 3
    i know this is an old thread but i changed my brake booster and it fixed my problem.
  • cheeze74cheeze74 Posts: 31
    I posted a message last year about my ABS and brake light coming on intermittantly. Now it stays on all the time. I suspect the CAB or controller to be the problem. I thought I saw a post once about a company that repairs them. Does anyone know who that company is so I can check into it? Thanks!
  • cheeze74cheeze74 Posts: 31
    edited August 2013
    I finally got to the bottom of the problem with my ABS and Brake lights staying on. They have on occasion gone out but mostly have been on. I took apart the CAB unit and removed the 12 volt ice cube relay, took it apart and bent the lower contact slightly so it could make connection with the moveable contact. It solved the problem! Installed back in truck and it is working fine! The Dealer wanted $400 to replace the unit and it was a simple fix! Never did find anyone that repaired the module but they would have probably just replaced the relay. Not an expensive item. Just wanted to let everyone know the solution to the problem.
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