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I recently purchased a '99 Dakota 4x4 Sport with 162,000 miles on it. The brake and ABS lights come on from time to time. Has anyone seen or had this problem before. I first thought it had something to do with the emergency brake. The brakes were done recently by the previous owner. Also the Check engine light stays on all the time. The truck runs fine, but I would like to get this resolved. Autozone says that the O2 sensor, catalytic convertor, or something to do with the left bank maybe the problem. Any help would be appreciated. Thanks in advance.
 

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i always thought or heard that if your brake light is on to check the alternator
 

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I'm not sure how it would (or if it would) affect the ABS light, but if the brake fluid is a little low it might cause the brake light to light up. This has been the case in previous vehicles I've owned. The owners manual doesn't specify and I don't see it specifically addressed in the Haines manual I have (or I haven't found it yet).
 

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You may want to have the speed sensor checked. A friend told me that could cause it.
 

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I recently purchased a '99 Dakota 4x4 Sport with 162,000 miles on it. The brake and ABS lights come on from time to time. Has anyone seen or had this problem before. I first thought it had something to do with the emergency brake. The brakes were done recently by the previous owner. Also the Check engine light stays on all the time. The truck runs fine, but I would like to get this resolved. Autozone says that the O2 sensor, catalytic convertor, or something to do with the left bank maybe the problem. Any help would be appreciated. Thanks in advance.
Those have nothing to do with the ABS system. The Dakotas have a
CAB (Controller ABS Brakes) that monitors the ABS system and has it's
own unique set of fail codes. It requires a special code reader to access
it on it's own test plug (not the OBDII test plug that is under the dash board).

There should be pigtail connector with 2 wires on the left side of the
inner fender in the engine compartment, where the master cylinder,
combination/proportioning valve, HCU and ABS controller is located.
Grounding a wire on this pigtail will give you a crude flash code that
you may be able to interpret..
Ie: "Flash, pause, flash/flash/flash" would show up on the ABS brake
indicator as code "13". Other than that, you would have to visit
a dealer to read the ABS controller fail code for you.

The ABS controller gets it's signals from the wheel sensors on each wheel
if you have all wheel abs - or - from the rear differential sensor (VSS)if it is the
RWAL version (Rear Wheel Anti Lock) version. AFAIK, the speedo is also controlled
from this sensor, so if your speedometer is not working correctly, this also points
to this sensor.

Usually, it's a bad wheel sensor or differential sensor but there are
other fail codes in the ABS controller as well.
 

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I'm not sure how it would (or if it would) affect the ABS light, but if the brake fluid is a little low it might cause the brake light to light up. This has been the case in previous vehicles I've owned. The owners manual doesn't specify and I don't see it specifically addressed in the Haines manual I have (or I haven't found it yet).
I just recently experienced brake failure and the ABS + Brake light coming
on my 98 magnum V8.

In my case it turned out to be a leak in the rusted rear brake line and loss of brake fluid in the master cylinder.

The master cylinder has dual lines go to the combination/proportioning valve, which has a brake fluid pressure switch on it.
This switch (activated) will operate the brake light, and the ABS light, which is turned on by the ABS controller, when it senses loss of pressure in the proportioning valve or HCU.
(Hydraulic Control UNIT that has the isolation and dump valve solenoids on it.

I also recently troubleshooted a 1999 dakota (magnum V6) that had both the brake and abs light on steady, but the brakes were still operating normally (without the abs function of course, which is disabled when the ABS light comes on) and the owner couldn't clear both ABS/Brake lights either.

He is now going to try replacing the rear differential (RWAL) speed sensor on his 2WD.
 

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change the speed sensor up on top of the rear differential, i would bet money thats your problem.
 

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change the speed sensor up on top of the rear differential, i would bet money thats your problem.
So far with my experience on these Kelsey-Hayes RWAL ABS systems,
that seems to be the most common type of failure, and if the sensor
is really bad, the speedometer can also be erratic, as the there is an
indirect connection between the two.

However, there are other types of failures that the ABS controller can
detect as well. It's just too bad, that Dodge decided to use a oem
RWAL abs system and not have provision to read the codes through
the standard OBDII connector.

You are forced to go to a stealership that has the reader for the ABS
controller and these are still very expensive in the aftermarket compared
to the OBDII code readers.

There is a provision to ground the pigtail coming off the ABS controller
to read the flash codes, but you have to be very observant to
interpret them. Here they are"

ABS codes used on 1998 Dodge Dakota (Kelsey-Hayes RWAL)
(4Wheel equipped ABS).
21 RF wheel sensor open
22 no signal from RF sensor
23 intermittent signal from RF sensor
25 LF wheel sensor open
26 no sig from LF sensor
27 intermittent signal from LF sensor
--------------------------------------------------
35 rear diff sensor open
36 no signal from rear diff sensor
37 intermittent signal from rear diff sensor
38 wheel speed mismatch
--------------------------------------------
HCU (Hydraulic Control Unit)
41 RF isolation solenoid open
42 RF dump solenoid open
43 RF isolation solenoid shorted
44 LF isolation solenoid open
45LF isolation solenoid shorted
46 LF dump solenoid shorted
47 LF dump solenoid shorted?
51 Rear isolations solenoid open
52 Rear dump solenoid open
53 Rear isolation solenoid shorted
54 Rear dump solenoid shorted
------------------------------------------
61 RF reset switch closed
Possible causes: leak in hydraulic system
Faulty CAB
Faulty hydraulic control unit (HCU)

62 LF reset switch closed
Possible causes: same as RF
---------------------------------------------------------
63 Rear reset switch closed
Possible causes: as for LF and RF
65 Main relay open
(open or short, poor electrical contact, faulty relay)
66 Main relay shorted
67 Pump motor circuit open
68 pump motor stalled
69 excessive dump time (failed valve body assembly or pump motor)
------------------------------------------------------------------
CAB faults
70 Controller Vehicle mismatch (faulty ECU/PCM)
71 Ram read/write
72 ROM checksum
73 Watchdog timer
74 System module T.O.
------------------------------------------------------------------
Brake circuit faults

78 Foundation brake red lamp
Possible causes: short to ground
Pressure switch in proportional valve out of
position or faulty
81 Brake circuit switch
Possible causes: open or short, poor electrical contact)
82 number of tone rings out of range
Possible causes: Faulty wheel speed sensor
Poor electrical connection
Faulty tone ring or wrong tone ring

88 Red brake light warning lamp
Possible causes: - red brake light short to ground
- Pressure switch in proportioning valve
out of position or faulty
-faulty CAB

89 Antilock warning lamp (ABS)

Possible causes: anti-lock warning lamp short to ground
- open or short circuit condition
- faulty CAB

Manual flash code procedure
ABS pigtail connector needs to be grounded to make the
ABS controller flash the ABS light in order to read the code

For code 13; it would be a flash, then a pause, then flash, flash, flash.
The last flashes would be short flashes
 

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Abs and Brake light on, speedo no work under 30

I just finished replacing the speed sensor on the rear differential.. Mopar part cost $55 with tax. 10mm wrench to disconnect battery; 13mm to remove nut to take brake lines off stud; 14 mm to remove stud holding sensor shield and sensor. Removed the electrical connection (clip has to be lifted) very gingerly looking at new sensor to see how it attaches. The sensor is a push in with an o-ring. Getting it out was my hassle. I tried pliers, and eventually used a screwdriver to pry it up. Unfortunately the cover that covers a coil inside broke staying in the differential hole along with the old o-ring. Stuck my finger in to pull it out, no go, tried a drill bit to wedge in there but another no go. It was loose and spun in the hole. Ended up using side of screwdriver to remove residue on inside of hole and was able to get it out with my finger. Geez. put dielectric grease on o-ring of new sensor and on electrical contacts and push it in. put on shield then, stud, put brake lines back on stud, the last nut and reattached the electrical connector. Turned on ignition for 30 secs, pressed on brake pedal. Re attached neg terminal to battery. Started it up and all the lights went out. Took a drive and all is well. Should have taken about 15 minutes if I knew how to remove the sensor the correct way. I didn't bother to jack up truck, since I fit under. Sounds like a common problem.
 

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change the speed sensor up on top of the rear differential, i would bet money thats your problem.
My ABS light and parking brake light were also on all the time. ABS was not working (tires would skid when brake was applied hard). I picked up a wheel speed sensor at Autozone for around $35. Backed the truck up on ramps, installed the new sensor with a 13mm end wrench and a 14mm deep socket in about 10 minutes. Hardest part was getting the pigtail wire off of the old sensor, LOL. Super easy repair and the truck is like new again. :)
 

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I just finished replacing the speed sensor on the rear differential.. The sensor is a push in with an o-ring. Getting it out was my hassle. I tried pliers, and eventually used a screwdriver to pry it up.

Unfortunately the cover that covers a coil inside broke staying in the differential hole along with the old o-ring. Stuck my finger in to pull it out, no go, tried a drill bit to wedge in there but another no go. It was loose and spun in the hole. Ended up using side of screwdriver to remove residue on inside of hole and was able to get it out with my finger.
Sounds like you had some fun removing it. :D

Geez. put dielectric grease on o-ring of new sensor and on electrical contacts and push it in. put on shield then, stud, put brake lines back on stud, the last nut and reattached the electrical connector. Sounds like a common problem.
Those sensors are a snug fit on the diff. Good idea to put some dielectric
grease on it for future removable.

The 1998 Dakota has two speed sensors. One is on the transmission o/p
shaft and monitors the output shaft speed for the PCM to shift at the
optimum rpm. It is the TSS or output shaft speed sensor.

The other one that often fails, is the the VSS or Vehicle Speed sensor which goes to the antil-lock controller (CAB) first and then the pulses are passed on to the PCM to determine vehicle speed to drive the speedometer.

It is important to know which is which, because some helplines erroneously
call the TSS the VSS and they are NOT the same function.
 

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I know this is an old thread, but I'm experiencing the same problem right now. Both my ABS and Brake lights are on. I've already changed out the rear diff speed sensor and it did nothing. Brakes seem to be working fine and there is no leak in fluid anywhere. I tried grounding the pigtail by sticking a paperclip in one hole at a time and touching it to the truck frame, but no matter which wire i grounded, the ABS light did not flash at all. Any more ideas?
 

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I know this is an old thread, but I'm experiencing the same problem right now. Both my ABS and Brake lights are on. I've already changed out the rear diff speed sensor and it did nothing. Brakes seem to be working fine and there is no leak in fluid anywhere. I tried grounding the pigtail by sticking a paperclip in one hole at a time and touching it to the truck frame, but no matter which wire i grounded, the ABS light did not flash at all. Any more ideas?
Forget about the flash codes on the ABS controller (CAB). You pretty much
need a special reader to extract those anyway.

IF you have both the ABS and Brake light on, and you have changed the VSS
speed sensor in the rear end, you MAY have an actual brake issue now.


Being a 2000, it is possible that your rear line is seeping brake fluid to have both
the ABS and the brake light on at the same time causing the brake pressure
switch to activate.

I had the same thing in my 1998 last year...brakes seemed ok, then coming
off an express ramp, the ABS and BRAKE light both came on at the same
time as my pedal went almost to the floor. I had about 2 maybe 3 brake applications on the brake pedal to slow down and crawl to a garage, before all the fluid in the reservoir was gone! Came as a big surprise!


Warning: the Dakota does not have a true isolated double braking system
master cylinder fluid reservoir..if you lose fluid in one..the brake fluid will
run down FROM BOTH THE FRONT AND REAR through whichever system
has an open line.dump ALL the brake fluid in the Master Cylinder fluid reservoir,
and YOU WILL NOT HAVE ANY BRAKES!

The rear wheel speed sensor sends a signal to the CAB (controller anti-lock
brake) which then sends the signal to the PCM via the CCD Bus twisted pair
wires. The pulses from the VSS extinguish the ABS indicator and the update
the speedometer.

The RED brake light is operated by the proportioning valve (next to the master
cylinder) which has the BRAKE PRESSURE FAILURE SWITCH on top
. If
the brake flluid proportioning valve( differential pressure) closes the contacts of that switch..the brake light will come on.

The brake pressure switch connects ground with pin 11 on the CAB
which operates the red brake warning indicator on the dash. (There is also
a signal called Brake Switch sense that goes into CAB (C1 pin 9)
and the PCM C3-24 as well.
This is basically the braking lamp switch that connects
ground
from when the brake pedal is depressed.)

For the RED BRAKE WARNING INDICATOR TO COME ON, THERE HAS
TO BE A BRAKE PRESSURE SENSOR THAT IS BEING CLOSED ON
the differential (proportioning) brake system valve with the switch located
on top. It goes to C1 pin 11 on the cab, directly I believe.


If you lift the connector off the brake pressure sense switch on the
proportioning valve, the light will go out because the switch is not there
to connect ground to the CAB sensor.
You should just do this temporarily,
as a test, to see if the brake pressure switch is the one that is setting both the ABS and Brake light. The lights should go out, until you put the connector on the
proportioning valve back on that is.

If there is fluid pressure difference detected, the lights will come back on again and you won't be able to clear them until the source of the problem (ie: low fluid pressure) due to brake fluid seepage..

through:
1) a rust pinhole in the front to back brake line
or 2) a leaking over axle brake line
or 3) the rubber over axle flex hose leaking
or 4) a wheel cylinder itself leaking..
 

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I also have had this issue from the first day I bought my Dakota
I noticed a badly rusted brake line in the engine bay and replaced
It while awaiting a new engine(Easier with no motor to get into
tight spots like that), I finally got the motor in and it's now running strong
(Thanks to carverman by the way), but I desided to move it around the
yard a little bit and when I hit the brakes after bleeding the line mind you,
the pedal we t to the floor and the second time I pressed the pedal down it
popped, the brakes grabbed, it stopped, the abs and the brake light went out,
and my master cylinder fluid level dropped about a 1/4 Inch.....was there a blockage
in the lines or what happened there?...oh and have had no further problems brake wize....
 

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I also have had this issue from the first day I bought my Dakota
I noticed a badly rusted brake line in the engine bay and replaced
It while awaiting a new engine(Easier with no motor to get into
tight spots like that), I finally got the motor in and it's now running strong
(Thanks to carverman by the way), but I desided to move it around the
yard a little bit and when I hit the brakes after bleeding the line mind you,
the pedal went to the floor
and the second time I pressed the pedal down it popped, the brakes grabbed, it stopped, the abs and the brake light went out,
and my master cylinder fluid level dropped about a 1/4 Inch...
..

was there a blockage in the lines or what happened there?...oh and have had no further problems brake wize....
You still had an air pocket in the line or in the caliper possibly even after
bleeding, especially after changing a front line? Or did you change the front to rear line?

The fluid went down because after what you thought you had bled
the brake line (and caliper)?, there was still an air (bubble) in the Master Cylinder still trapped and not allowing full line pressure to the proportioning valve.

This is the valve that differentiates the master cylinder pressure between the front lines, (which have larger calipers and need more pressure), and the rear drum brakes, which have smaller wheel cylinders and need less pressure.

The proportioning valve (next to the master cylinder) also has the brake
line pressure switch coming off it.
If you lose brake pressure due to split in the line somewhere, applying pressure with the brake pedal will cause the switch contact to make and the brake light will come on. The ABS will come on if the rear line loses pressure as well.

If the line splits on you on the road, you have about 2 applications of the brake pedal and ALL THE FLUID IN THE MC Reservoir WILL BE LOST!
This is NOT A TRUE ISOLATED BRAKING SYSTEM ON THE DAKOTA because
of the proportioning valve. Any split in any line will cause a dramatic
loss of brake fluid and consequently, air will be sucked into the MC and
at that point the pedal will go down to the floor!
As I mentioned in my previous posts..the Dakota braking system SUCKS
big time. Why?

1. Chrysler didn't use stainless steel brake lines and a split in ANY line will
cause a dramatic loss of braking power, possibly leading to a needless accident.

2. The Master Cylidner used by Chrysler in the Dakota is not a TRUE dual
braking system, because the proportioning valve is in the circuit and it
distributes brake fluid under pressure. A split in any line and the piston
in the proportioning valve moves to one side, the side with the low pressure
will cause the brake light to come on..but REPEATED APPLICATIONS OF THE
BRAKE PEDAL (YOU HAVE ONLY ABOUT 2 APPLICATIONS) AND THE BRAKE
FLUID IN THE RESERVOIR IS DUMPED INTO THE LEAKY LINE AND YOU WON'T
HAVE ANY BRAKES AFTER THAT.

So on older Dakotas, it is probably best to replace ALL the brake lines to be on the
safe side! IMO.
 

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Old thread, but this is the problem I'm having. I don't see a 2 connector pigtail anywhere near the brake booster/reservoir? Could you take a picture of it?

Those have nothing to do with the ABS system. The Dakotas have a
CAB (Controller ABS Brakes) that monitors the ABS system and has it's
own unique set of fail codes. It requires a special code reader to access
it on it's own test plug (not the OBDII test plug that is under the dash board).

There should be pigtail connector with 2 wires on the left side of the
inner fender in the engine compartment, where the master cylinder,
combination/proportioning valve, HCU and ABS controller is located.
Grounding a wire on this pigtail will give you a crude flash code that
you may be able to interpret..
Ie: "Flash, pause, flash/flash/flash" would show up on the ABS brake
indicator as code "13". Other than that, you would have to visit
a dealer to read the ABS controller fail code for you.

The ABS controller gets it's signals from the wheel sensors on each wheel
if you have all wheel abs - or - from the rear differential sensor (VSS)if it is the
RWAL version (Rear Wheel Anti Lock) version. AFAIK, the speedo is also controlled
from this sensor, so if your speedometer is not working correctly, this also points
to this sensor.

Usually, it's a bad wheel sensor or differential sensor but there are
other fail codes in the ABS controller as well.
 
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