2nd Gen Non-Engine/Transmission ABS and brake light

[GAmes]

I've got 'em both. I read quite a few posts and the common failure was the speed senser. I gambled the $$$ and the new sensor didn't fix it. So here are the things that make my problem a little different than the posts I found. The lights don't come on right away, and don't come on with speed, and the speedometer works just fine. The lights come while sitting at a stoplight, idling in neatral with the clutch disengaged. As a test, after I had isolated when the lights illuminated, I just turned on the key, didn't even start the engine, just put my foot on the brake. After about 30 seconds the lights came on. I don't have front ABS, just back. 97 2WD 3500.



Gary

 

[Ramboy]

I can't say for sure, but I think that even after correcting the problem, you still have to have the codes scanned off to clear the lights.

 

[GAmes]

There is no computer to "scan off" but I did remove the CAB fuse to clear it, as per the manual. No change. Anyone else have an idea?

 

[J. Steve]

I had real similar symptoms on my '02 4X4 when it had only 7,165 mi. It was the left front wheel (speed?) sensor, and was replaced by a dealer. Thankfully by warranty and it solved the ABS and break light problem. So I'm probably not telling you anything you havn't heard, but thought I'd say it anyway. Hope you solve the problem.

 

[GAmes]

I figured out which terminal to ground to get the DTC code 9, a code that disappears when the key is turned off. I've checked all the wires and they look good. It's looking more and more like the CAB has failed:{ . I disabled it to get rid of the light and will fool with it after I get back from Lake Fork. The bass are biting and I do have my priorities.

If anyone has found another cause to this problem please let me know.

 

[GAmes]

TTT

I spent all afternoon chasing wires and cleaning connecters. I still get the lights just by holding the brake pedal down a few seconds, not moving. The light will stay off if I make quick stops and do not keep the brakes engaged. My multimeter is not up to the task outlined in the service manual but without any input from you guys I guess I'll have to bite the bullet and get a new one.

Turns out the bass were not biting all that well, but a bad day fishing is still better than a good day at work.

 

[Koa Man]

My truck had the abs and brake lights stay on and it was due to a small hole in the vaccum line. I patched the hole and the lights when off. Recently the lights started staying on again and I found another vaccum leak. Repaired that and the lights went out.

 

[Greystoke]

I had the lights too...

It is hard to say what your problem is without knowing what year/model your truck is. I worked on this same problem for about 5 months before finding my problem. My truck would be fine until approx 40 mph then the lights would come on. Also my ABS and cruise control did not work, but my speedometer was ok. I replaced the rear axle speed sensor with no change. I replaced a bad vacumn check valve with no change (other than my heater controls work really fast now). I finally took it all apart underhood per the powertrain diagnostics manual and checked everything having to do with the speed control system. I checked the speed control servo and it wasn't functioning properly. After making a wiring harness to allow me to individually control the speed control servo solenoids I discovered that my speed control servo was good, meaning my wiring to it was bad. So I took off the PCM connectors to do a continuity check between the servo and the PCM and lo and behold PCM connector #3 was loose. I cleaned everything up and put it all back together and took it for a test drive. You should have seen the smile on my face turn to a frown when the lights came on at 40 mph again. So I took apart the brake swithch and it was bad. Fixed my problem and I am all smiles again. Moral of the story, "It's not fixed till the real problem is found. "

 

[GAmes]

97 2WD 3500

I put it in my first post. No vacuum brakes, so that isn't it. The brake switch??as in brake light switch? I have studied my wiring diagram and don't remember a switch, but I will look again. I think I'll disconnect my trailer brake controller too.

 

[parcher]

This could be as simple as LOW BRAKE FLUID LEVEL! Check the brake fluid.

 

[GAmes]

Brake fluid is right at the top line, where it has been since I replaced it 11 months ago. But thanks for the come back.

 

[Paul Somers]

Me too

I have pretty much the same problem. My brake and abs lights would come and go. Very intermittent. Now they are on solid. Soon as you turn the key on brake and abs lights come on and do not go off till key is turned off. Have been swapping PM with Games and he has been very helpful but still no fix. Don't really want to start easter egging this with expensive parts that you can't take back. I went to AutoZone to have codes read but it isn't storing codes that can be read with OBDII scan reader.

 

[GAmes]

Found the problem

Greystoke turned on the idea light with his mention of the brake light switch. That switch sends a signal to the CAB and also to my Kelsey brake controller. Disconnected the controller and the light stays off. Reconnected it and the light came on. Disconnected it and the light stayed off. Just guessing here, but could the brake controller be the culprit? Guess I'll put my hardly used sensor in the classifieds and get a Prodigy.



Paul, I hope you find a solution to yours.

 

[Greystoke]

Glad I could help

Good to se you found your problem GAmes, now if the steering bracket I just bought from Darin would get here I should be done with all of my problems.