My ABS and Brake warning lights are On in my 1996 Ram CC 4x4 5.2L (Rear ABS only). This was the case when I bought the truck 4 years ago - at that time I read the error codes from the ABS module (via grounding the appropriate pin on the dagnostic connector and reading the blink codes) and found that the Rear Speed Sensor had a fault. I replaced the sensor and everything was working fine.

Now the lights are back on again (15k miles later), but No diagnostic codes are read from the ABS module. Grounding the connector pin results in No Codes being blinked out. It's been a while since I read the codes the last time, but I followed the same procedure but am not getting any codes read out.

So, is there another failure that would cause the ABS AND BRAKE warning lights to be on all the time? Truck brakes fine, the fluid level is good, as well. Could a bad sensor at the master cylinder trigger this? A bad switch at the Emergency Brake pedal? Etc.?

Thanks!

 

My guess would be the output sensor on the trans. If it starts to fail, ABS & Brake light come on, cruise control sometimes won't work either. The ABS module should store codes if the light is there...If you feel like asking around some shops to have them scan the module, you should be able to find out what's definitely going on.

When the rear speed sensor was replaced, did you install a new harness? If not, obviously check out the wiring on the original one.

If you you've checked all these out, download the factory service manual from the FAQs section (if you haven't already) and look at where all the ABS wiring is, especially at the PCM..and check for bad wires and the like.

P.S. try to use the search function on here or google, there's plenty info on ABS/Brake light problems.

 

When that happened to me it was because of my wheel cylinders were leaking.

First I replaced a few sensors, the light went off for a little while, then came back on.

Are you losing brake fluid? Getting a soft pedal? Pull your rear wheels/drums and check around the rubber bushings of the cylinders.

 

I just fixed this same issue. There is a ABS Sensor that reads the tone ring of the ring gear. Its mounted on the top of the rear diff. Looks like below...

 

He said his fluid level is fine...
He said he replaced that sensor too...

 

Thanks for the replies!

I have replaced the ABS speed sensor before, but I am not getting ANY codes out of the ABS module at this point, so nothing points back to that sensor again, right now.

I am not leaking brake fluid. I did replace a leaking power steering cooler last month, though ;-) My driveway is spot-free, for the moment. Braking performance is fine, just these warning lights are on.

I did test the cruise control last night (I don't use it that often) and it is working fine, too. Also, the speedometer is reading just fine, no gaps or other issues on that.

I have the (hardcopy) factory service manual, as well as the download. I guess I'm just trying to understand what are the triggers for those lights (that they come on together) and then I'll start checking them 1 by 1. Oh, and I did the searching for similar threads (brake or ABS warning lights, etc.) before I posted my question ;-) It's only proper Forum etiquette.

Thanks!

 

I agree with 97 black ram on the rwal sensor in the diff. If you have metal flakes moving around in there it can cause that sensor to go whacky. I would check my diff and try cleaning the sensor off. You can easlity pull that sensor to at least check it.

If you have already replaced it how long has it been. New parts are supposed to work but there is no guarantee that they will, except for the fact that there is a warranty so that can help.

 

I am getting No error codes from the Rear Wheel ABS controller. Also, the Rear Wheel Speed Sensor was replaced about 15k miles ago (and 3 years or so). I would at least expect to get an error code, if that sensor was reading erroneously (from metal flakes) or if the harness or sensor had gone bad again...but I'm not getting any codes from the module.

That's why I'm trying to understand what else may trigger the warning lights.

Also, I've been unable to find a part number for JUST the brake fluid level sensor/sender/switch - anyone have a P/N or source?

Thanks for your help so far!

 

Do you HAVE a fluid level sensor??

Brake switch, proportioning valve, a leak in the system, could all cause what you are seeing. Any way you can look at the data stream while driving? Speedo working correctly?

 

My brake lights are working ok. Others had mentioned a level sensor, but I'll have to double-check. The speedometer is working fine...no gaps, inconsitencies or fluctuations. My cruise control is working fine, as well.

Just the @#$% ABS and BRAKE warning lights are On ...and No error codes are available on a diagnostic dump of the Rear Wheel ABS controller.