ABS kicked in for no apparent reason (low speed brake)

[davem]

I've searched/read multiple posts on this .......

I have a 2001 Explorer XLT 4x4 V6 SOHC with 172,000 miles (all but 36K are mine). My daughter (who has the rig at college) reported the ABS kicking in when coming to a stop a few times, but no ABS light was ever lit up. I kinda refused to believe it until it happened to me while I was driving it this past weekend.

Its only happened 3-4 times EVER (ie in the past 2-3 weeks), but has always been while coming to a stop from a low speed, and mine was also during a lane change/slight turn.

Sounds like it could be an ABS sensor, wheel hub, or brakes themselves.

I'm guessing I should wait until this happens more often before taking it to the shop for repair ? (easier to diagnose)

In the mean time:

1) Can I assume the brakes are working OK ?
2) Will the ABS work correctly when truly needed on ice/snow ?


Thanks.

 

[rathrbcruisin]

I had that happen to a 98 windstar i had, every stop sign. I had 150k miles on it and decided to pull the fuse to the abs. The brakes will still work, you just won't have abs and the abs light will be on all the time. a small piece of electrical tape over it was good enough for me. If the red brake light comes on, that's the regular brake system that needs to be looked at. I would think that the abs would work in the ice/snow, they're working now on hard pavement.

 

[gatzdon]

Using Forscan, you can pull the extended codes (may or may not tell you which ABS sensor). (forscan is free to download and will give you the extended codes from all systems).

This is most likely one of the front sensors causing the problem. Most affordable option is to replace the entire hub assembly with the ABS sensor (connector is up under the front bumper).

Make sure you get an Autozone hub with lifetime warranty and use lots of antisieze compound so it's easier to replace should it fail again (aftermarket bearings are known to not be as reliable as the OEM bearings).

Think about replacing anything else while your at it, especially if you already have a lifetime warranty (tie rod ends, upper ball joints, brake pads, etc...)

 

[rb142]

Classic sign of an intermittent failure in one of the wheel speed sensors. You probably won't have any codes at all. The best way to find out which one is to watch the signals on a scope, but most people don't have one.

The brakes will work fine, but the ABS may come and go. It will eventually get worse.

 

[gatzdon]

Classic sign of an intermittent failure in one of the wheel speed sensors. You probably won't have any codes at all. The best way to find out which one is to watch the signals on a scope, but most people don't have one.

The brakes will work fine, but the ABS may come and go. It will eventually get worse.

My ABS light never came on, but with Forscan, I was able to get codes from the ABS module indicating an intermittent failure in my front driver's side wheel sensor (don't remember the exact code, but I think it was C1145).

The ABS system won't through a regular OBD code.

 

[ccm2001]

Had same issue. Just unplug one of your abs lines. Change your hub assembleys and your fine .

 

[davem]

Thanks everyone for the replies. I'm probably going to let it ride for awhile and deal with it once it occurs more frequently.

Just curious, roughly what is this gonna cost for:

1) wheel hub
2) speed sensor

Thanks.

 

[sehaare]

Thanks everyone for the replies. I'm probably going to let it ride for awhile and deal with it once it occurs more frequently.

Just curious, roughly what is this gonna cost for:

1) wheel hub
2) speed sensor

Thanks.

http://www.amazon.com/gp/product/B000BZAEGY?keywords=Timken%20SP450200&qid=1445346556&ref_=sr_1_1&sr=8-1

 

[ccm2001]

I picked up 2 Mevotech assembleys for 175$ off rockauto and bought a 32mm for the axle nut took about 3hrs for both sides depending on rust. Good tip leave the 3 hub bolts in half threaded and beat the nuts it will help loosen the hubs out of the nuckle

The wheel hubs comes with a abs sensor built in

 

[gatzdon]

If you let it go, keep in mind that while it's technically not dangerous, it will increase your braking distances. If a driver is used to coming up fast on a stop and then hitting the brake, they will go an extra 5 to 20 feet than they expected.

 

[sehaare]

If you let it go, keep in mind that while it's technically not dangerous, it will increase your braking distances. If a driver is used to coming up fast on a stop and then hitting the brake, they will go an extra 5 to 20 feet than they expected.

this got me thinking, the above would be true if the driver was use to the antilock kicking in every time they stopped. I didn't think that the anti lock kicked in unless it sensed one of the wheel not turning. so on normal stops the anti lock doesn't kick in, only on stops if you start to skid (wet, ice, high speed). So on normal stops you wouldn't see any difference. Am I wrong (wouldn't be the first time).

 

[gatzdon]

this got me thinking, the above would be true if the driver was use to the antilock kicking in every time they stopped. I didn't think that the anti lock kicked in unless it sensed one of the wheel not turning. so on normal stops the anti lock doesn't kick in, only on stops if you start to skid (wet, ice, high speed). So on normal stops you wouldn't see any difference. Am I wrong (wouldn't be the first time).

ABS is designed to sacrifice braking distance for vehicle control. As such, the braking distance is always increased when ABS kicks in, even in dry conditions on normal road surface.

The potential issue is that people who come up on a stop fast, don't factor in that extra few feet when the ABS kicks in for a faulty sensor reading on a dry, normal road surface.

People who make gentle stops may find the ABS to be annoying, but probably won't stop long because of it.

I speak from experience. My ABS was kicking in for every stop until I replace the hub bearings (which include the ABS sensors). Depending on the condition of the vehicle, if the Forscan tells you which sensor is faulty, you can try replacing just that side.

 

[colintrax]

Before you waste time and money on this. Pull the front sensors and clean them and the wheel. Road grime and dirt collect in the wheel cutouts and over the sensor. Every time I hit the trail my abs is overly sensitive until I clean it

 

[rwcfrank]

I second the cleaning of the ABS sensor, I had the same problem and while changing the pads I pulled the sensors. One was covered with grease and debris and the other was clean. After reassembly everything works perfectly. I had thought the problem was run out of the rotors but they were all dead straight and true.

 

[1997XLTRollover]

OP if your truck has 170k+ on the original hubs. I would just change them. Get a pair of Timkin's (factory Ford) from Rock auto and just change them. My 96 has 146k and I just did both hubs. 1 was bad the other was fine but with that mileage they're going to go soon. I'd rather change them on my own time, than the dead of winter when they will most likely fail (Murphys law). For 200 bucks you will have 2 new abs sensors and 2 new hub assembly's.

 

[gatzdon]

Got a chance to look yesterday. Forscan Lite let me see the real time PID values for each of the front sensors and the rear sensor.