Is the ABS hyper-sensitive in these trucks?

[Drafter]

02 2500 CTD. Dealer replaced the front brakes (calipers and rotors I think) before I bought it. My first impression was that the pedal felt firm and the brakes were smooth and responsive and 99.5% of the time they are. It seems like the ABS is kicking in on occasion under heavier braking. Not knowing the ABS feel in this truck, I would describe the pedal as getting harder to push, downward pedal motion becomes jerky, there is more of a grinding noise than the ABS whir I am used to, and decreased braking performance. I have to try some more things to reproduce it but it seems that being pointed downhill, first brake application after start up, braking when making hard turns at parking lot speeds. No ABS light comes on when it happens. I was thinking about bleeding the brakes incase some air worked into the ABS. Can I pull a fuse to disable the ABS for troubleshooting to see if that is what I am feeling?Is the ABS sensitive to different wheel speeds?Think there could be an trouble code and no light?I have done a number of brake jobs on a bunch of cars and never seen an intermitent brake problem.

[Mopar1973Man]

Interesting...

I know that most of the 2nd Gen 24V trucks I drove seem to get brakes rather quickly in the pedal. Under heavy braking usually you can lightly feel the ABS pump kick in. The only time I really feel the ABS pump is on loose ground or icy roads. As for grinding noises arn't good... Is it the actual rotors making the noise or the ABS pump? You might want to bleed some fluid out and see if there is debris in the fluid or dark colored. If its dark colored dump it, flush the system, and reload it.

Bleeding setup

Wasted brake fluid... 8|

[Drafter]

Well, it is definately the ABS kicking in. Turning into a parking space is the sure way to get it to do it. The "grinding" is thru the pedal and Im sure is the ABS pump now. Listening to a ball game on AM and I could hear the electrical noise of the ABS pump thru the radio as it kicked in. The fluid is old and dirty, so I pumped out the reservior topped it off with new, but the bleeders are corroded so I couldn't bleed off the old fluid. The calipers were not replaced by the dealer, they just put new pads in squeezing the pistons back in. It is clear from the rust they didn't open any of the brake circuits.Got any tricks to dealing with bleeders rusted in place? This truck came from the salted road capitol of North America and I am afraid every simple maintenance job is going to be an ordeal. Heat and or PB blaster?I wonder if the tires have even pressure all around, they look even...

[Mopar1973Man]

Well, it is definately the ABS kicking in. Turning into a parking space is the sure way to get it to do it. The "grinding" is thru the pedal and Im sure is the ABS pump now. Listening to a ball game on AM and I could hear the electrical noise of the ABS pump thru the radio as it kicked in. The fluid is old and dirty, so I pumped out the reservior topped it off with new, but the bleeders are corroded so I couldn't bleed off the old fluid. The calipers were not replaced by the dealer, they just put new pads in squeezing the pistons back in. It is clear from the rust they didn't open any of the brake circuits. Got any tricks to dealing with bleeders rusted in place? This truck came from the salted road capitol of North America and I am afraid every simple maintenance job is going to be an ordeal. Heat and or PB blaster? I wonder if the tires have even pressure all around, they look even...

Ok... First thing is to get a 6 sided socket that fits good on the bleeder screws. Hold the ratchet in place and whack the ratchet handle to loosen it. Normally this is enough to get it loose... PB blaster, WD-40, or similar won't hurt. But I have a feeling your in the same boat I was you going to have to pull the calipers off and open up the pisons and clean the piston cylinders out. Check for rust and check for seal damage... If you deside to use heat make sure you get the piston and seal out of the calipers before heating it up... Don't want to damage the pistons or seals. viewtopic.php?f=45&t=247 Also before I forget when (and if) you pull the calipers apart check you pistons for binding. It really simple. Take all the seals out (weather seal and main seal) then clean the caliper good (I used soap and water then compressed air dried.) The pistons should drop in there holes without PUSHING at all. It you got to push it in the piston NEED to be replaced. If there is rust in the cylinders you can use a hone stone to polish out a little bit but if its bad you'll have to replace your caliper ($120 replace). I've been changing my brake fluid as recommend by the dealer at every 30K miles. Which happens to be roughly once a year... http://mopar.mopar1973man.com/cummins/2ndgen24v/maintenance/maintenance.htm Second off once you do get them loosen and bled you want to snug them not super tighten them... Overtighten the bleeder screws will damage the ends of the screws and the seats in the calipers it will cause them to leak. After that get some vinyl tubing that will fit over the bleeder screews. Cut it about 1" long then heat the tubing with a cigarette lighter and then quick squeeze the end of the tube with pilers to seal shut the tubing. Now you got new bleeder caps to keep the water and mud out of the screws... This will prevent the screws from rusting again! Seals and pistons are a dealer only part but there cheap. Seals are like 3 bucks and a piston is $21 bucks. Well I better stop... LOL

[REFLancer]

I got the parts from the Dodge dealer like Mopar man did and fixed up my rear caliper,changed the fluid too...MUCH better!I never used the brakes hard,so they got froze up in the back,my rear pads lasted 250k+lol.Now when I come to a stop I mash em' down from time to time to keep them free,it works good.

[Drafter]

250k out of the rear brakes is tough to beat!Yesterday AM I hit the bleeders with PB Blaster in the center and around the outside, drove the truck to work and home again. I found one of the caliper slide bolts was missing on the rear in the AM and picked up new bolts and bleeders at lunch. It turns out that the bolt snapped off at the caliper, not sure if it sheared or was over-torqued. I would say over-torqued because the caliper seems to be working fine and as if the bolt was there, pads are even. Working with rusty calipers reminded me why I have gotten lazy and started buying re-man'd loaded calipers for brake jobs. The rear bleeders opened right up after the PB (I'm never sure if it is the PB or fate). $190 for a pair of loaded rear calipers (Morse) or $88 for a single unloaded caliper (Fenco) at the local parts stores. The math isn't tough, but the other caliper looks like it had been replaced and the pads are good. New rear brakes and not have to deal with anything from them for a good while, might be worth replacing the pair.I bled the rear using the conventional 2 man method after messing around with a mighty-vac and kludged up mason jar that wouldn't hold enough of a vacuum to draw fluid consistently. Pedal is just a bit firmer, still getting random ABS kick in. Front tires were 15 PSI different (thanks tire shop knuckleheads), and that seemed (not sure) to help ABS during slow speed hard turn.That missing bolt in the rear can't help the ABS, but I don't think it is causing the issue. Talking with a motorhead buddy, he suggested rust on the gear used by the ABS sensors, not sure if it could be an issue with these models but worth a look.

[Mopar1973Man]

Dang... comparing against my caliper those things are nasty looking... Wow! :wow I would opt for rebuilt caliper after looking at that myself I'm sure you might have a few froze pistons in these things... Not to mention the lost and broken bolt in the one you got the pic of... The reman calipers at NAPA was suppose be around $120 bucks... Or am I just got the gift of gab... :confused:

[Guest]

wow, that has seen a lot of utah top soil!!!!!! :wow

[Drafter]

Well... Browsing the local national part store chains made me think that I was going to have my pick of calipers, all different brands and options etc. Calling around showed otherwise. One Mfg isn't offering them anymore and nobody had the adapter bracket I needed with or without the caliper, but they did have the caliper. Dodge could have gotten the bracket in 3-4 days. With nothing to lose, I went after the broken bolt in the adapter bracket. Cut a slot for a flat head screw driver in the exposed bit of the bolt, but it just rounded out. Then I started to drill it out. I've never had much luck with drilling out bolts or using easy-outs (which I don't even bother owning), but this one worked. Started with a 1/16th diam bit, which immediated wobbled out of my punched centermark. I stopped just at 1/32 deep and dragged it back to the center with a small Dremel burr. This time the 1/16" bit stayed remarkably centered and I worked up to the minor diameter of the bolt, when the old bolt threads let go with sudden bind. Of course I was missing my 5/16 - 18 tap, so I needed the old threads to come out. Back together and torqued down with Anti-sieze. If car MFG's had an "anti-sieze option", I'd be all over it. I got the brakes bled and fluid changed, but the ABS is still kicking in every now and then. I found these posts, with no definative answer. http://www.dieseltruckresource.com/dev/ ... p?t=202000 http://dodge.justanswer.com/questions/1 ... mmins-scan The second guy watched his speed sensor output over the OBD2.... I wonder how much time he spent before that, then the Dodge tech has him replacing a bunch of stuff that doesn't seem to be helping... Ouch. I think that I have new bearing/ sensor assemblies since the hub and cotter pin are shiny new. These seem to only be available as an integrated unit. Any reason to go in after them? The first post above the guy did just that and they were fine. Talking to the dealership mechanic, who is out of state, he suggested a bad ground, which wouldn't throw a code or other bad connection. I have to learn more about the software ( http://www.obd-2.com ) to see how to watch and record those sensors. So, onto the wiring.

[Drafter]

So, I finally got around to having a proper computer talk to my truck. Turns out that the speed sensor in the right front drops off to 0 at around 5 mph, then the ABS does it's thing, like it is supposed to. I went over every ground I could find, cleaning and reassembling with die-electric grease and knew it would have no effect and it didn't. I measured the resistance for each speed sensor and they are all cool as far as I could find in google. The plan is to replace the wheel bearing/ hub/ speed sensor with a genuine Dodge part.Anybody think that this will not solve the problem for some reason? My trusted mechanic thinks it will as well as the dealership who is going to cover it. I would pick up a wheel bearing from the junkyard to check out the theory, but it isn't my dime.other ideas? I will post of the hub-ectomy results here.

[Mopar1973Man]

Either the sensor is bad and can't sense slow speeds or there is a problem with the rotor as for triggering the pulse... I clueless but I would love to hear what you find... Post pics I would love to learn about this one... :thumbsup

[keydl]

Before I bought a new one I would clean up the top of the tone ring teeth and the face of the sensor, probably with a file and a little caution. Then I would compare the clearance with the working one, there may be mud on the mount. If a business card locks under the sensor it is close. Check the face of the sensor that reads the tone ring for crack or distortion from impact. With new wheel bearings, it may have been hit when the old ones went outThe other thing is to get the grounds shinny and cover with grease on all the parts or soak them with paint to stop corrosion.The careless and poor of sight ought to stop reading and avoid contaminating the brake fluid with a petrolium product.There is a little lube pump , for gear oil I think, that works well for pumping the brake fluid back from the wheel. Remove the fluid form the MC and with a new clean bleeder screw fill the MC by pumping from the wheel. It backflushes the abs valve and when the fluid is proper looking, move the new bleeder to the next wheel and start over. No-sieze can be used on the threads of the old bleeder if care is taken not get it on anything but the threads, same with the inverted flair nuts with care to keep any trace from the inside of the flair.keydl

[Drafter]

Update. It is fixed.Better late than never. The dealer I bought the truck from replaced the right front wheelbearing/ speed sensor assembly with a factory part for no charge. The wheelbearing was not worn, I was told that sometimes a sloppy worn bearing can cause speed sensor issues. This sensor dropped off to 0 at speeds under 5 mph, when the left still registered speed, activating the ABS. This started intermitently and happened more consistently over 3-4 months. Removing the ABS fuse disables the speedometer. Disconnecting a speed sensor will keep the ABS from activating and keep your speedometer working(I picked the right one because I knew it was bad).Unfortunately I didn't get the old one to take a look at, so I couldn't check the tone ring for rust, mud, or anything, from what I understand these (2000-02) trucks have a sealed tone ring and sensor integrated into the bearing hub. Hope this helps somebody.