I was coming home from snowmobiling in upstate NY on Tuesday and my "ABS" idiot light came on. I did a pedal check and everything seemed to be functioning normally. Later that day when I restarted the truck the light was off. I was out and about tonight and when I got home I could smell something funny and it was coming from the left front corner of my truck. No it wasn't that distinctive brake smell you get when someone drives with parking brake on. So anyway I touched the rim and it was hot. I went around to compare it to the right front rim which was fine. It was only the left front rim that was hot. Anybody have a diagnosis? Is my caliper hung up? What would trigger the ABS light?

I can see this costing me money

 

sounds like its going to be quite a bit of money. not sure how much but i can give you some ideas to think about. ABS is a cool little system. sometimes it will set codes for mechanical failures in the MECHANICAL brake system. this happens because the wheel speed sensors see that one wheel is decelerating faster then the other ones. if this happens enough it will go into an ABS stop event and it will run the valves in the HCU (Hydrolic Control Unit) this pulses hydrolic fluid supply to that wheel until it doesnt decelerate as fast or matches with the other wheels. it has to be a pretty bad problem to have an ABS light on and a code but only have a mechanical fault in the base brake system. Ex: siezed caliper piston. good way to test for this is to see if it has a brake pull. BUT, since you do have a ABS light it could be that you have a valve internally in the HCU that is sticking open or shut (depending on witch valve). so each wheel has a inlet isolation valve that allows fluid to the wheel and a outlet dump valve that relieves pressure to the brakes. these pulse back and forth during an ABS stop event. if it is a valve sticking, (most likey the inlet valve trapping pressure in the brake curcuit without the dump valve knowing to operate), then the HCU unit has to be replaced as a unit and cant be serviced and taken apart. Or if you have a mechanical failure then the wheel is just slowing faster then the others all the time and the ABS module is like "oh my god holy crap" and sends a light that something is wrong or because it wants to go into an ABS stop situation but the situation isnt sevier enough. unfortunatly its not a wheel speed sensor gone bad and giving a bad signal because you said the wheel is really heating up. that would have been the easy cheap fix. I know its possible to have the ASB module through a light because of a mechanical base brake concern but i have never seen it my self. in this case to fix a siezed caliper piston you would need to buy a new caliper. HCU is about $800 caliper is about $150 if i remember right. and the wheel speed sensor would have been about $45 but thats not your problem cause your breaks are hotter then weenie over an open flame. but anyways something to think about. good luck. hope my crash course in abs helped a little. most likly Mechanical brake issue not ABS issue if only one wheel is heating up.

 

I would get the codes read from the ABS module. Often, the reason for a dragging brake is stuck caliper pins and they simply need to be removed and greased.

 

Thanks for the info fellas. I haven't had the breaks off this truck yet. What are the caliper pins. If I remember correctly from my old truck there is the two big bolt that hold the caliper on and then the pads just fit into place. I remember these little wire springs that would attach to the back of the pads to keep outward preasure on the pads when the brakes weren't being applied.

 

If your profile is up to date, your truck is a 2002. After checking the caliper and probably fixing it, I would also flush your brake system which I am going to bet has never been done. Optimum maint. on the brake system requires flushing every 3 years. Most people never do this little but important piece of maint. until they either have a problem or do their brakes. Just a suggestion. I noticed the other day at Pep Boys that they have a synthetic Dot 3 fluid that supposedly attracts less moisture.

 

No I sold the 2002. I now have a 2006. It only has 20k miles on it but Im two months past my 3/36 warranty.

 

yep probably caliper pins siezed. thats not to bad.

 

The caliper slide pins are what attaches the floating caliper to the anchor plate. One some vehicles, the slide pins are bolts themselves that just turn out, while on others (like ours I believe), the caliper is bolted to the slide pin.

Remove the bolts that hold the caliper to the slide pin and remove the caliper, then you should be able to pull out the slide pins (top and bottom). There are boots that you need to be careful with. It's the slide pins that you pull out that need to be lubricated. I've seen them so badly stuck that they won't come out. And, it's also possible that the one or both pistons are stuck. In either case, you'll probably want to replace the caliper rather.

This diagram is from my service manual for a 2004. Yours should be nearly the same.

 

Well I think I fixed it. I went over everything and all seemed ok. The pin were fine but I gave them an extra kiss of grease anyway. The calipers weren't seized. The only problem I could see was with the pads themselves. There is a metal clip top and bottom on each pad that rides in the top and bottom channel. The clips and the channels had alot of rust build up. THe inside pad was pretty stuck, I to fight to get it out. So I lightly sanded the end clips and channels and put a light coating of brake grease on each. I put it all back together and went for a five mile ride. When I got back I touched the rim and it was ice cold. So I have my fingers crossed that I fixed the broblem. Thanks for all your help fellas.