Abs light and park brake light

jerrod2007 · 06-03-2010, 12:09 AM

My abs light and park brake light come on randomly. If I lug my truck it'll happen but now it's just dinging on occassionally at random. My edge insight doesn't give me any codes.

Posted here because I thought one of my mods caused this

dcm3497 · 06-03-2010, 12:28 AM

check your brake fluid both lights will come on if the fluid is low and trips the sensor. if its low check your brake pads may be time to change

TurboDiesel7 · 06-03-2010, 12:39 AM

do your cruise control work? i know i hit a little branch in middle of the road which broke my abs sensor and i had those lights and cruise control wouldnt work the plug was in the rear end differential

kmkdiesel · 06-03-2010, 01:24 AM

I had this same problem with my old 6.7 and if I remember right, it never happened with the stock clutch but after putting in a 4200# dd clutch if I lugged it pulling out of town, it would always trip the abs and brake light, dealer replaced speed sensor and a couple other things, which nothing worked it still did it,

***Shibbyutman*** · 06-03-2010, 07:27 AM

It is a bug in the voltage detection software in the ABS unit, there is literally nothing you can do about it. It only happens on the manual transmission trucks while lugging the motor, the voltage drops even for a half a millisecond and it'll trip the lights even though the voltage returns to normal once the engine commands higher charge rate. TRW is to lazy to issue a TSB to update the software in the ABS module.

If this happens when you aren't lugging the motor then you have a genuine problem, but otherwise keep on truckin'

Oh, and ABS codes are on a private bus meaning you'll never be able to pull codes from the OBD-II port.

jerrod2007 · 06-03-2010, 09:09 AM

Well I do get it lugging but stillget it occassionally cruising and my speedometer does a quik drop and bounces around

07rattle · 06-03-2010, 09:23 AM

Mine does it to if I lug it down, but if yours is doing it while cruising you might want to start looking around at some stuff. Make sure your sensors are plugged in and no wires are broke. Check your fuses to, even the fuses marked spare.

***Shibbyutman*** · 06-03-2010, 09:26 AM

if that is the case you may want to pull your rear wheel speed sensor out of the rear diff and clean the end of the magnet to check for metal debris. Even a little metal back there from the break in period of the diff can occasionally cause the wheel speed to drop out, which will mess with the speedo and trigger lights in the dash. While you are in there looking at that look the sensor over really good and clean the flange off that it mounts on the diff to make sure it remates to the proper depth when you put it back together. Look for any cracks or misalignment of the head on the sensor as those are typically the first signs of them failing.

sonnlaw · 06-03-2010, 05:44 PM

Mine does the exact same thing! I can not put a finger on a cause as of yet. I clear the non existent codes with the smarty and it will disappear for a 100 miles or so. Fluid is fine, brakes feel great. Mine started after getting new shoes? Maybe at the next service I will rotate the tires and check the wheel speed sensors.
All my gauges will drop for a split second and the two lights will ding..ding..ding for 20 or so min. then they will stay on.
While the lights are on the cruise will not work?
Any other ideas?

***Shibbyutman*** · 06-03-2010, 06:03 PM

Quote:

Originally Posted by Shibbyutman

Oh, and ABS codes are on a private bus meaning you'll never be able to pull codes from the OBD-II port.

Quote:

Originally Posted by sonnlaw

Mine does the exact same thing! I can not put a finger on a cause as of yet. I clear the non existent codes with the smarty and it will disappear for a 100 miles or so. Fluid is fine, brakes feel great. Mine started after getting new shoes? Maybe at the next service I will rotate the tires and check the wheel speed sensors.
All my gauges will drop for a split second and the two lights will ding..ding..ding for 20 or so min. then they will stay on.
While the lights are on the cruise will not work?
Any other ideas?

Key cycling it will make the lights turn off because they are ignition latched faults meaning the lights will stay through 1 or 2 key cycles. You need a DRB-III diagnostic tool to read ABS codes. That would be your best way to narrow down your problem instead of just trying parts. We can recommend what parts may be bad, but trying to diagnose a fault in the ABS system without them is like trying to find out what injector is causing a misfire without reading codes. All you can do is throw parts at it until you get a hit somewhere.

***Shibbyutman*** · 06-03-2010, 06:05 PM

cruise control is dependent solely on wheel speed to know how/where it needs to maintain the trucks speed, if the code your ABS has just thrown invalidates a wheel speed be it a rear or a front the cruise control doesn't know what one to trust so it won't work either.

sonnlaw · 06-03-2010, 06:11 PM

Thanks a ton shibby! I will rotate the tires and check the sensors like described above. I just wonder why once I clear the non existent codes, everything will be fine for a certain period of time? I.E, cruise works perfectly.
I have also noticed that I have ZERO problems until I go on a trip over a hundred miles or so, then the lights ding and cruise quits?