marks2500

My brother is on the road and having me contact you guys, he is towing his trailer 12,500#. The red EMERGENCY BRAKE light and amber ABS light came on. He said he cycled the key 3 times and got no codes. Does anyone have any suggestions or know what is happening? He is concerned.

singleturnout

Rear Sensor Will At Least It Was On Mine When The Same Thing Happened

marks2500

Thank you, I will relay the info.

crobtex

Speedo usually acts up, also.

RATTLINRAM

Here is an old post of mine from 9-27-2004 that may help some.
I replaced the rear wheel speed sensor (RWSS) that is located on the top of the rear-end differential and my ABS and BRAKE light have gone off.

Now for a few findings that I came across before replacing it,,,,

*With the rear wheels up on jack-stands, The speedometer did not function at all when in gear at approx 30-35mph. (guesstamated),,,,, however, putting it back down on the ground and driving around,,,,, everything worked fine. (other than ABS and BRAKE light still on)
*When I removed the old RWSS, There was no continuity between the two prongs on the sensor.

I had a few options on what to do,,,
Spend the $60-some bucks for a dealer to put it on their diagnostic gismo (every shop I went to said that only a DC dealership could access the Controller for the Anti-lock brakes. (CAB) and I had already figured out that the CAB does not set any codes in the ECM that are readable by the average DRB scanner.) I figured I would gamble and spend the $33 for the RWSS and the reason for my decision was based on a theory that my front sensors were OK because the speedo and Cruise Control worked fine when all four wheels were on the ground.
This is only my theory and maybe one of our gurus can tell me if I'm correct or not.
On a 4 wheel ABS equipped truck, the CAB must get signals from all 4 of its data gathering sensors in order for it and the speedo and cruise control to function properly.

1. Front Left wheel
2. Front Right wheel
3. RWSS (remember that there is only the one sensor mounted on the pumpkin)
4. And the Transmission Speed Sensor which is mounted in the transmission.

When the RWSS fails on a 4 wheel ABS system, apparently the ABS shuts down and trips the warning lights to let you know it has disabled itself, however the CAB still sends the data from the Front sensors and the tranny sensor to the ECM, which enables the speedo and cruise control to be unaffected.
I also think, this is why the trucks that are equipped with only the Rear Wheel ABS systems have problems with their speedo's and cruise control when the Rear Wheel Speed Sensor goes bad. Evidently this system only uses the two data gathering sensors,,,
The RWSS
And the Transmission Speed Sensor

Does this sound like a fair explanation?

One thing I'm sure of,,,,,,,,,, I don't have those BLASTED idiot lights aggrivating me!

BTW the part number for the RWSS on my 2 wheel drive,,,, 4 wheel ABS equipped 2500 is 56028187AE and this is the same part number for the Rear Wheel ABS only trucks also.
NOTE* However,,, it does appear that the 4 wheel drive trucks have a different part number according to the parts guy I spoke with today.

marks2500

Thanks again, info. relayed.

rockittboy

mine did that after i got stuck in the mud, sensors get all blocked, jammed, wet. try spraying out the caliper area and see whats up.

Chrisreyn

Has he checked his trailer connections???
The first thing I would check is the brake controller connections and the trailer plug/wiring harness.. a short to ground in ANY part of the harness or plug can trigger a brake warning light....this happens a lot when folks tap into the wrong wire when attaching the brake controller, or get moisture or dirt in the plug....

Never hurts to check the simple things first............CD

"K.I.S.S.~~~~" Keep It Simple, Stupid"

fschiola

If it's not a sensor, the next thing to check is the stoplight switch. They aren't very expensive ($12.00 at Auto Zone) and have 3 circuits in them that control the ABS, stoplights and cruise control. Any one of them can be bad without affecting the other two and can display the symptoms you described. .

RickG

I had the same problem and it was a front speed sensor . It isn't that urgent . Brakes will work the way old brakes worked without ABS . There is a liability concrn though .

billv45

Hi Mark, I'm a newbie here but have been doing some research on this very problem since my '96 2500 2WD is intermittently displaying the ABS/Brake lights also. It appears that 9 times out of 10 it's a bad ABS speed sensor on the rear differential if it's a 2WD (a dealer only part $63 list) A 4WD has some front sensors that can go out also. I changed out my speed sensor and it appears that I am the 1 out of 10! I did find some instructions by Lary Ellis on how to display the fault codes from the ECM that ground out the number 13 wire of the RWAL link data link connector but I guess I'm not doing something correctly since I do not get anything. Here is the thread with the instructions: https://www.dieseltruckresource.com/...rwal+data+link
.
I inserted a wire into what I think is the data link which was mounted to the dash frame about a foot from the steering column on the passenger side (may not be the original mount as a PO had a kill switch and electric brake module installed in that area too), it's a black 16 pin connector and no 13 is black. I grounded no 13 to the dash frame, key on, key off and engine running and was not able to get any flashes from the ABS light. Am I doing something wrong here?

Please note that while the lights are on, the ABS is not functioning.

04ctd

why don't you post up what year his truck is, what mods he has, and where he is,

and maybe some one with a BullyDog can read his codes,

or he can pull into someone's house & check stuff?

DR3500

I have had the lights come on in mine before while leaving a stoplight (3 wheels spinning) the light was on with no codes and went out by themselves a little while later. Basically the computer freaked out because all the sensors were not giving it what it thought they should. see ifthe lights go out and no codes don't worry about it.

boostjunkie1

I had this same problem just a couple of weeks ago and it was the ground wires that come off of the ABS Module to the fenders/rear frame!!! Everything cleaned up and tightened down and no furthur problems.

Spooler

I am not sure about Dodge but if you are low on brake fluid both lights may come on. That is why you will not see a code. Do a visual check of the brake fluid level.