The brakes on my 2007 Ranger XLT have recently become grabby. When they did grab, I stopped in a straight line, and if I was going fast enough, the antilock mechanism activated, causes them to pulse. Typically, I would feel an abnormal sensitivity as I was stopping at the corner early in the drive. My ScanGauge didn't show any codes, so I took it into a trusted shop.

They determined that a wheel speed sensor was acting hinky... that as the driver was braking, three of the wheel sensors would show decreasing speed, while the driver side front would also slow down but not at the same rate as the other three. So, it was replaced.

The situation has definitely improved but I don't think it's completely resolved. I still feel an increased sensitivity to how I apply the brakes. And yesterday, I almost missed my turn, and the antilock activated at a point when it normally wouldn't have. At least I stopped straight.

Gas mileage has been unaffected, so they're not dragging. But I think something is still off. What say you?

 

How are the brake pads? Once they get worn there can be some grabbing brakes.
If you have been traveling rock or dirty roads dust could be affecting the brake operation. A spray cleaner should be able to clean the brakes thoroughly.
If you have been on rock roads, it’s possible to get small pieces of rock under the pads or stuck in the calipers.
Good luck Topsail👍

 

I live on a NC barrier island. The roads are all paved down here. I don't think there are any issues with the pads or my mechanics would have mentioned it. They are absolutely trustworthy and competent enough that our local police department gets all of their work done there too.

I am not hard on brakes. I'm inclined to come off the gas early and just roll up to a stop rather than aggressively braking like it was when I lived in the big city. Anyway, I appreciate your input.

 

Maybe the tone wheel is the problem, not the sensor.

Don't know if you have 4WD or 2 but I think the ribs on the back of the rotor are the tone wheel for the 2WD. The sensors sense the ribs passing by. Looks like 4WD has it in the hub.

https://www.rockauto.com/en/moreinfo...t=1896&jsn=711

https://www.rockauto.com/en/moreinfo...t=1636&jsn=780

 

Well, that's something new to me. Never heard of "tone wheel". And I have 2WD. FWIW, I stop straight. It's not pulling either way.

A few minutes later.... Hmmm. Most of the potential symptoms don't apply but one does: The increased sensitivity of the brakes on normal stops. Thanks for the heads up.

 

The proper word is ring. I blanked on it. There are different types. Some of the higher end scanners will show the wheel speed signal.

 

I have a ScanGauge permanently installed that sits just above my rearview mirror, but it doesn't show any codes. I thought that it would when I bought it, and while it has the capability of reading codes, apparently not *those* sorts of codes. I mostly have it to provide me with more detailed information than my idiot lights can provide, such as voltage and transmission fluid temperature.
That being said, I have a much better understanding of what may be happening. Excellent video! Thanks for posting it.

 

The emergency brake cable maybe sticking causing the rear shoes to be extended out. I had the issue on my 02. Luckily JC Whitley had new cables

 

UPDATE:

The brakes still want to grab more enthusiastically than they should, but only on occasion, which means I have learned to immediately come off the brake momentarily when I feel them starting to misbehave. But that's just a bandaid. The problem has not been cured.

I drove to my mechanic's place of business two days ago and 1) not a single episode occurred on the drive there, and 2) his parking lot was already full, and he had more than enough work to keep him busy for the foreseeable future. He opens at 0730. I arrived at 0738 and he's already full? I took that as an omen and just kept on going, stopping at a grocery store and then going back home. Not a single episode going home either. I figured if that was my experience driving it that day, it would have been his as well. I hate intermittent problems. Time to change tactics.

To that end, I ordered a Bluedriver Bluetooth Pro scanner along with an OBDII splitter to accommodate the Bluedriver scanner along with my preexisting ScanGauge II. The Bluedriver does actually scan ABS faults, along with airbag, etc... all the stuff my ScanBauge doesn't. This new scanner interfaces with my iPhone and I should be able to document misbehavior as it happens while I'm just driving around. It's supposed to be delivered today (Amazon is my friend). We'll see if this can finally pin this maddening misbehavior down!

 

A quick comment or two, hoping it's helpful...

Online service manual shows that your 2007 Ranger will have only a single WSS (Wheel Speed Sensor) in the rear, to sense the axle speed:

https://charm.li/Ford/2007/Ranger 2W...Sensor - Rear/

So, if you graph all the vehicle's speed sensors, you'll only have 3 graphs to monitor.

I didn't watch the entire video posted by @BareBonesXL but, as is typical of South Main Auto videos, it's a good one, as you already discovered. For those who didn't watch it, it nicely shows how a speed sensor that's behaving oddly should be reasonably easy to identify by comparing WSS graphs under various driving/braking conditions -- something I've done many times in the past, for a 2004 Ranger and for other vehicles, using an OBD2 scantool (as inexpensive as $15) and FORScan or similar software. Be sure to record the datastream as you drive, for later analysis. Sometimes the misbehaving WSS is only subtly misbehaving unlike in the video.

Also, presence of ABS Diagnostic Trouble Codes (DTCs) is typically annunciated to the driver by the ABS dashboard lamp. But they typically reset on a power cycle. So, even though I don't see you mentioning any ABS lamp activity, you should read any ABS codes with your BlueDriver before shutting the truck off if you do see a flashing or steadily lit "ABS" at any point during your drive.

Good luck!

 

Thus far, I haven't noticed any codes, idiot lights, or dashboard icons lighting up, though that might be because my eyes are on the road when the brakes grab.

 

Creaky makes a good point about the number of sensors. You described four in the first post but he says that you should only have three. What's up with that?

Mismatched tire size could cause a problem. The ABS is expecting all four to rotate at the same speed. They all need to be the same size.

 

I was going by something I'd read rather than by actually looking for myself. My bad, but I knew I didn't know a speed sensor or tone ring when I see one, so there wasn't much need for me to crawl around trying to see. Still, this is an annoyance I don't need, and I wouldn't involve myself at all except for the fact that it's intermittent and thus far I'm the only one to really get the full Monte when the ABS comes on unexpectedly. I might be braking but I sure didn't expect *that*.

 

I'm not sure what you mean in your post before this one. Can't tell what "that" refers to.

But, you either misunderstood what the shop was telling you or the shop itself was confused. Either way, it sounds like there was a speed mismatch betwen left and right front sensors. Let's see what the scanner shows.

 

I'm not sure which "that" you are referring to, so we're even!

Yes, there was a speed mismatch between the left and right front sensors. They did say that. They said that the other sensors (that I misinterpreted to be that 3 out of 4 sensors) showed a slowdown at an equivalent speed when braking while the left front read faster speeds for a few moments compared to the others' readings. It was deducted that the left front sensor was misbehaving, and so it was replaced.

Better? I apologize for being unclear.