Pulsating pedal, ABS problem, no ABS light

Ok guys. I've never had an ABS problem before. I thought my wife's 2002 XLT pulsating brake pedal was due to warped rotors. NOPE! Four new rotors (needed two of them anyway) and still had the problem.

So then I pulled the ABS fuse and no more pulsating pedal. Of course she doesn't have ABS anymore either. So, is there a way to track down the problem. I can't afford to throw more parts at it. Before I pulled the ABS fuse, there was no ABS light.

So, how do I track down this ABS problem?

thanks
Austin

It most likely is a failing wheel speed sensor. Would the ABS kick in when you were almost to a stop? Say, below 5 MPH? IF so, it seems that one of the speed sensors is dropping out and the ABS system thinks the wheel locked up, so it activates the ABS. The easiest way is to have a scanner that can read ABS data and drive is to see which wheel drops out.

Where could I find a scanner that read the ABS computer?

Yes, it is below 5mph when it pulsates.

You probably won't find one at AutoZone or anything, unless it clearly states that is can read ABS codes/ data. Mostly it is the higher end scanners such as snap-on, OTC or the factory Ford scanners. Sometimes you can find PC based scan tools that can be pruchased on-line but usually the ABS is bundled as an add on. Most repiar shop should have the ability to read ABS Data. The downside is paying them to do the diagnosis and test drive.

I just found an Actron ScannerPus online that says it reads ABS codes and data for about $150 and up depending on where you get it. otherwise the PC Based AutoEnginuity scanner looks nice, a little pricy but you add on features and enhanced packages for other makes as you see fit.

Did you find the fix?

Hey Austin,

So my Explorer was doing the same thing. Vibration and pulsating. I replaced the front rotors and pads...stilll same problem. Then I found that my upper ball joints were shot...replaced those and vibration is gone but not the pulsating. I pulled the ABS fuse #5 and voila....no more pulsating! Awesome. But now I have a ABS light on my dash (wasn't there before). What could be the underlying issue? Sensors? I'm running slighly bigger AT tire...

Thanks,

Doug

I had the same issue with my 02 and if you can believe it, it was caused due to uneven wear of my tires. The Ford mechanics thought that I would have also experienced having the 4 wheel drive kick in while at speed (due to the sensing of wheel spin caused by the uneven circumference of the tires) but in fact the only thing it did was activate the ABS when I came to a stop..very weird. Changed the tires and it went away. I would have bet anything that it was a sensor and that's probably a good bet for what you're describing.

I also have this same very issue on my 97 AWD and I believe that it is more than likely a sensor issue as well.

I have a slow speed ABS issue when slowing to a stop and hit about 5 MPH My ABS kicks in the peddle ratchets down and I apply more brake to get to a stop.. ABS feels like it's working as it should except comes in play at low speed for no reason dry clean paved roads bellow 5 MPH or so.. Tires all the same size and aired to 29psi , wear is even.. I just installed new front rotors and new brake pads with slides and anti rattle kit.. stil have same issue.. Bled brakes all the way around to flush the system used 1qt of Dot 3 fluid.. still same issue.. I was talking to a guy in the parts store.. said he went threw the same thing last week and it was a front ABS sensor..

Is there a way I can tell if it's the left or right front sensor? It's a 4X4 and is a real pain to install a new one just to swap it out in the other side if I didn't guess right the first time.. Cold weather is setting in and I need to do this ASAP as I'm working outside.. Thanks for your help! I have a Ford work shop manual.. I don't have a brake out box or ABS scan tool... I have a volt metter.. George

PS I'm thinking about the Actron ScannerPus CP9580 Is this the right code reader?
Can I get a better one for the money? Will it tell me left or right ABS sensor is needed.. Or will I still need to guess? I'm looking at $169.. Does it come with the ABS and OBII cables for the three vehicles it states? It don't say anything about what comes with it.. I'm looking at it in Advaced auto Parts.. Please help!! George

Scanner might work. . .you really need to read 'Graph LIVE data ' . With no ABS light that should mean no code posted. Like others said the system only thinks the wheel is locking up, it hasn't 'lost' the signal completely. With my laptop software i can monitor wheel speed, i would expect you to see the speed of all 4 wheels with one showing '0mph' for a brief moment. i doubt a ohm meter will tell you anything.
When i had my problem i paid $50 for a brake shop to diagnose the problem, might be a little more since there is no code. With the Actron they say the scanner can read live data, if that means ABS sensors i'm not sure, i'd read the reviews carefully.

check front wheel bearing seals if the Hub vents are full of wheel bearing grease ABS can't read the correct speed.

elrod

ok I have replaced the front rotors pads calipers hoses rear wheel cylinders shoes drums I am getting a low speed loping or pulsing feeling I cant find anything loses all the bushings are good but I do have a left front wheel bearing that is bad and making a lot of noise I am wondering if it is possible that the vibration noise from the wheel bearing is effecting the abs sensor causing the abs to pulse and that is what I am feeling does any one have any ides

Good info here. My ABS light has been on since I bought the truck 2 1/2 years ago. I don't think my ABS works at all. Never did anything to try and fix it though.

Truck pulsates at low speeds

Guys, the pulsating at low speeds drove me bunkers too for months. I'm very particular about my vehicles. I first suspected the front brakes pads and rotors were due a change out, so they were replaced. My friend Vince (73 yrs. old) been a mechanic at his inspection garage for 50 years, he took the business over from his father. This guy has experienced it all. Anyway the truck still pulsated at low speeds after the front rotor and pads change-out (we knew the front calibers were good too). So, I asked Vince to put it back on the lift. We inspected the 4X4 drive shafts, the upper and lower bearings. the whole steering mechanism, the differentials and etc. Same problem occurring, the truck is pulsating at low speeds. I even ordered new ABS harness with new sensors for the front and rear. I ordered the ABS stuff after reading this forum, just in case u know (ETD 2 weeks). In the meanwhile, I purchased new rear brake shoes, drums, and associated new spring kit. I told Vince the pulsating was like applying the emergency brake lightly is how I'm experiencing it. Well, up on the lift the truck goes again. Vince pulls the left rear wheel off, then the brake drum. He inspected the brake shoes and comments, "Bill, these rear brakes and spring looked to be in great shape, almost like new, no sense in changing these out. Well, we could have ended right there, but we checked the right rear brake too. The wheel was remove, Vince struggled with the getting the drum off ... It was TIGHT AND RUSTY. He manage to get the drum off and knocked out the rust by dropping the drum onto the floor. The right rear brakes and springs were in good shape. Vince backed off that right rear brake assembly adjuster, reinstalled the drum and wheel and ADJUSTED BOTH REAR BRAKES EVENLY. I backed out of his garage stall and drove all over the neighborhood for 20 minutes waiting for that pulsating to reoccur ... IT HASN'T PULSATED SINCE ... It's been over a week now. I though my truck was simply wore out, but NOT!!! My 2002 Customized Ford Ranger XLT 4X4 has 157,000 miles on it, I well maintain it ... I'm 67, been retired for 3 years and this truck will probably out live me (HA!). Under the hood I have labeled the history of this truck on the front cross over piece, like "Lower ball joints 05/2012" and etc. I use the truck now for going to the firing range, or to play the PA. Lottery. It's not for sale! Well, I hope this 'finding' helps you as it has me. Good luck!!: