2nd Gen Non-Engine/Transmission Brake and ABS lights on

[RDMueller]

This is probably just a coincidence, but immediately after loading about 2000 lbs of dirt into the bed, as I drove away I noticed that the brake and ABS lights were on. No problem with braking whatsoever. I got home and unloaded the dirt, but the lights stay on. Checked for codes on the odometer, nothing. Inspected all parts of the brake system, all normal. Fuses checked. Disconnected batteries for 10 minutes, reconnect and turn key to run, lights come back on and stay on.



Did a couple of short test drives now that the truck was empty. Noticed that initially after I start the engine both lights are on. Then as I start to drive, the lights extinguish but the speedometer reads zero. Then at about 10mph the speedometer comes back to life and the lights both come back on and then stay on regardless of whether moving or stopped and the speedometer operates normally.



My first step tomorrow would be to go down to Auto Zone and have them check for codes. However I have already read that an OBDII won't retrieve brake/abs codes, need the far more expensive DRBIII scanner which I doubt they have.



I also intend to check the speed sensor on the differential. Any other ideas of where I should look or what to check? Thanks!

 

[B.G. Smith]

Most likely the sensor in the differential as it is also the speedometer feed. I had same problem with a 99. The sensor had collected metal particles and the speedometer was jumping around and lights on. bg

 

[Road Dog]

The odometer will only cough up ECM and PCM codes. You need a more advanced scan tool to read the ABS module. I would start by checking the rear wheel ABS sensor on the rear diff. Clean the connector and make sure the sensor is properly seated.

 

[cavalrycop]

mine did same thing speedo worked but brake and abs light on no codes. replaced rear abs sensor all is good.

 

[RDMueller]

It was the rear wheel speed sensor. Went down to Napa, bought a new one - $35, works like a charm. I do have an idea what may have caused it to fail in my case. More on that this evening with pictures...

 

[RDMueller]

So, as I stated yesterday, my first order of business was going to be to check the rear wheel speed sensor. When I went to remove it this morning, the sensor actually separated from it's housing. The sensor came right out and the housing stayed in the differential. By looking at the new one, you can tell it is all one piece and not meant to come apart. Obviously I had found my problem. See pics:

Now, as to why it was cracked, I can't say for certain, but I have a pretty good hunch. See this picture:

As you can see, I have one of those turn-over goosneck hitches. When the problem began I was hauling about 2000 lbs in the bed. In this photo I have about 1000 lbs in the bed. When the truck is empty there is a good 7-8" clearance between the bottom of the hitch and the speed sensor. In the above pic, that clearance has dropped to maybe 4". I didn't get under the truck yesterday prior to removing the load from the bed, but I'll bet that with that amount of weight, it was pretty close. One bump *might* have been enough to cause the hitch to contact the sensor and crack it. I'll never know for sure, but if I was a bettin' man...



One final thing, after installing the new sensor, I started the engine and while sitting there, the brake and ABS lights stayed on. Now I'm disappointed thinking something else must be wrong, but I decide to go for a test drive anyway. As soon as I got moving, the lights went out and have stayed out since!

 

[RustyJC]

I know on my 2002 4x2 3500, B&W supplied a plug for the gooseneck receiver when the ball wasn't in use. They specifically warned against turning the gooseneck ball upside down because it would hit the differential under jounce. Sounds like that hasn't changed.



My BMW motorcycle runs a self-diagnostic on the ABS brakes every time you turn on the ignition. The brake and ABS lights stay lit by design until the bike is moving at least 3 MPH. It has to see a speed signal from both the front and rear tone rings before the brake and ABS lights go off.



Rusty

 

[RDMueller]

I know on my 2002 4x2 3500, B&W supplied a plug for the gooseneck receiver when the ball wasn't in use. They specifically warned against turning the gooseneck ball upside down because it would hit the differential under jounce. Sounds like that hasn't changed.

This is really good to know! I bought the truck used and it already had the gooseneck hitch installed. I haven't used it so far and never had any info on it. I guess that is the hazard of buying a used vehicle and then not getting info on any aftermarket add-ons. Lesson Learned! At least it ended up only costing me $35 and an hour of troubleshooting.

 

[Stmpplr]

Well, I posted this same problem a week or sr ago. I had suspected the rear wheel sensor and CC posted his experience as exactly thre same. Just finished installing the new sensor and both the brake and abs lights are still on.
Any ideas?
Thanks,
Jim
p. s. All my local parts shop, including NAPA wanted at least $55. 00 for the part. Geno's had it delivered in 2 days for $28. 00. WTG GENO'S!!!!!

 

[Stmpplr]

Just a bump to see where to check next. Truck functions properly, but brake and ABS light still on all the time.
Thanks,
Jim

 

[HHhuntitall]

You checked all fuses? Being a '95, if the brake light fuse is blown, it will illuminate the lights. After that, I'd check for a vacuum leak. No vacuum to the sensor on the fender will illuminate the lights as well. If it doesn't have an update, there is a TSB about motor oil being pulled up into the lines on '96 and earlier trucks. This oil can deteriorate some of the rubber boots in the cab, as well as the sensor, not to mention stopping up lines when cold.....

 

[GAmes]

Do you have a trailer brake controller installed? I found that unplugging my controller would turn out the lights. I traced it to a connector behind the drivers side tire inner fender that was full of water.

 

[Road Dog]

Well, I posted this same problem a week or sr ago. I had suspected the rear wheel sensor and CC posted his experience as exactly thre same. Just finished installing the new sensor and both the brake and abs lights are still on.
Any ideas?
Thanks,
Jim

I've had the lights turn on when the brake fluid was low but still above MIN. Topping up the reservoir "fixed" the problem.