I have a 00 Quad Cab that started lighting both the ABS and Brake lights on the Dash. Checked fluid level (OK), had a friend of mine scan the code but now I am not sure where to start. Below are the Codes and probable causes I found doing a search:
78 – Foundation Brake
1. Red brake lamp short to ground
2. Pressure switch in proportioning valve out of position or faulty
3. Faulty CAB

35 – Rear Sensor Open
1. Open or short circuit condition
2. Poor electrical connection
3. Faulty wheel speed sensor

37 – Intermittent Signal From Rear Sensor
1. Open or short circuit condition
2. Poor electrical connection
3. Faulty wheel speed sensor

81 – Brake Switch Circuit
1. Open or short circuit condition
2. Poor electrical connection
3. Faulty Brake Light Switch

Poor Electrical connections - checked, cleaned them, Brake lights are good.
Questions are:
What is a faulty CAB?
Does anyone know how to test a wheel sensor?

Thanks for any info, Jim

 

Something I have learned about these sensors. Some people have reported that low brake pads can trigger both lights to come on... just me 2 cents.

Mine came on when I bought the vehical, Im trying to diagnose it now. The front brakes are pretty much gone. Also going to check the wiring, test the sensor and clean the sensor. If all else fails, Im replacing the sensor. Not sure how much they cost? And also am not sure how to test the sensor lol.

 

I have the same problem and have been researching this for a few days now.

It's a speed sensor for sure if your speedometer doesn't work (in conjunction with the ABS and Parking Brake light staying illuminated) until a certain speed (average on other forums was about 25mph). 2wd trucks only have one on the rear diff but 4wd trucks have one on the front and rear.

Brake Fluid level and the sensor in the Master Cylinder are other possible issues. A top up of brake fluid or flushing the brakes is a fix. Tapping a stuck sensor in the M.C. is another.

My problem, however, is electrical I believe. My ABS and Parking Brake light only come on when I switch on my headlights. If I leave it just with the running lights they don't come on. I've checked all the fuses (in the interior panel and under the hood) but haven't checked the relays. I also suspect it could be a dirty fuse not connecting properly? I'm not sure if anyone has solved my unique issue yet (I call it unique as I could not find this specific issue in about 50 other forums that I searched).

Any help would be great and I will post a reply if/when I fix the problem!

 

Well my speedometer is working fine so I think that can rule out the sensor? Brake pads in the front are relatively new back one should be good also (<4yrs and only about 5k a yr)
Does any one know what a "Faulty CAB" is? Thanks for your inputs

 

Something I found on justanswer.com

"The PCM uses a speed pulse input received from the Controller Anti-lock Brake (CAB) and internal programming to decide what vehicle speed and distance messages are required. The PCM then sends the proper messages to the instrument cluster circuitry on the CCD data bus. The CAB uses an input from the rear wheel speed sensor and internal programming, which includes a programmable pinion factor to compensate for different axle gear ratios and tire sizes, to determine what speed pulse output is required. The CAB then sends the proper speed pulse to the PCM on a hard-wired circuit.

Read more: http://www.justanswer.com/questions/1x8yo-abs-and-brake-light-came-on-at-the-same-time-the-speedo-will#ixzz0elq2lsjP"

 

Have your friend clear the codes and then test drive it and see what comes back. Some of those could be old codes that have been repaired and noone cleared them. You don't usually see that many different issues pop up at one time.

 

Your CAB is located in between the firewall and the fuse box underneath the hood. I just played with mine, as well as the relays, and my ABS and Brake light have gone away. Based on my earlier findings and now this I suspect a loose wire somewhere near the CAB or fuses/relays. Not gonna worry about mine. A Faulty CAB error code could simply be a bad wire so get in there with a flash light and have a look around. Jiggle the CAB and make sure the wires are secure and undamaged.

 

OK Thanks will do. Right now though there is over a foot of snow outside and not enough room inside to work so it will have to wait for slightly warmer temps. Thanks again