So I have a 2010 peterbult 388, with factory traction control. It will apply a little brake for 1 second than let off than do it again. On off on off on off. doesn't do it all the time. it is pretty random. might not do it for a hour or so than will do it pretty steady. will do it at all speeds. It was doing it today at 65 with the cruise on. no codes, no lights, still does it with traction control switch off. weird. It will also do it with the truck stopped and parking brake off. when it is doing it you can watch the brakes move. pulses on off on off on off. I have had it to my local truck guy twice. of course it will not do it when I drive over there. Anyone have a good place to start? If I unplug the traction control valve on the back it stops but than the abs and traction control lights are on. Thanks Steve
Traction control and ABS are tied together. It's getting a signal that the wheels aren't matching the speed the speedometer is registering. I'd say a wheel sensor is bad, tone ring isn't in one piece on a hub or the brain has taken a dump. Could even be wires from wheel sensors to control module. I'd start with checking wires myself, if they look suspect maybe replace the sensors. Might be hard to see the ring on the hub but if it's broke or even fubar'd in a spot it'll throw things off. Heck a sensor may have gotten shoved out of its mount a bit and the gap to the ring is a little wide causing an erratic signal. Gotta love electronics! Haha.
As stated above check all ABS harness at wheels and sensors first. But I just this last harvest we had a 07 KW doing the same thing It turned out it was the control module for ABS. For the most part ABS systems are fairly trouble free. But have never liked linked traction control with ABS especially in off road use. Truck Shop
Isn't a dash light supposed to flash when traction control is active, i.e. when a wheel is actually slipping? If not, I suspect above...control haywire. The only other possibility is it thinks a wheel is spinning but how could that be, how could it see more teeth passing the sensor than reality?
You are correct Birken. The light used to flash on when you were spinning. doesn't come on when brakes are pulsing on off.
I had a similar problem with my 2000 KW right after I got it. I had just done some work on the ABS as the previous owner had pulled the relay that's behind the kick panel & stuffed a piece of paper in the warning light so it wasn't on all the time- there's a fix. But I digress. Closing the gate headed out walking back to the truck (idling) I heard "pssst-pssst-pssst" & when I got in the ASR & ABS lights were coming on intermittently, then stopped. Couple hundred miles later started again. Turned out to be the sensor wire on the RR that was zip-tied to the brake line and had rubbed on a fitting & shorted- vibrate just right & suspension up/down and short, then be OK, then short....
So I think its not a electronic problem. May be the brake control valve between the rear axles. I noticed it only does it when the air pressure is above 120psi. so I unhooked all the electric connectors to the valves and it still did it. While I was fooling around with it I noticed that if I tapped on it the brakes applied. pretty strange. so I believe something is gone wrong inside the valve. so I ordered a new one.
Got the new valve installed and seems to have fixed the problem. That was kind of weird, I have never had a brake valve go bad like that. I think the ABS needle valve in the top was letting air burp past it. While the air was building up the check engine light came on. now I have a fault with #4 injector and #2 actuator . Cat C13, 500K miles. How does anyone make a living with these pieces of sh#t? I feel sorry for you guys that run this stuff over the road. I rarely go more than 150 miles from home, some times I think that's to far. time to start looking for some nice late 1980's w900s. really getting burned out on stupid electrical problems. Rant over................ for now Maybe its the wiring? I will start investigating it in the AM. maybe look under the valve cover and see if I can find anything. I does seem like it has a little miss now.