1997 XLT V8 AUTO AWD:
WOW, I HAVE READ ALL THE POST ON THE ABS SYSTEM KICKING IN FALSELY, JUST PRIOR TO STOP. GREAT INFO IS POSTED.
MINE IS DOING THE SAME ERRATICALLY, ON ABOUT 1 OUT OF 100 STOPS.

I HAVE THOROUGHLY INSPECTED THE STANDARD ITEMS (PADS, CALIPERS, MASTER CYLINDER, CONTROL UNIT,ETC AND THERE ARE NO PROBLEMS THERE. ALL IN PERFECT WORKING ORDER AND NO LEAKS OR BINDS.

FOR SOME REASON, ON OCCASION, THE ABS SYSTEM FALSELY SENSES A WHEEL (OR WHEELS) HAS STOPPED JUST PRIOR TO COMING TO FULL STOP (LESS THAN 10 MPH). THE ABS LIGHT DOES NOT COME ON (THE BULB IS GOOD). WHEN THIS OCCURS, THE ABS KICKS IN AND THE PEDAL PULSATES, AS IT SHOULD IF A WHEEL WAS SKIDDING.

ALL POSTS SUGGEST THE A WHEEL SPEED SENSORS ( 3 TOTAL IN MY 1997, 1 ONE EA FRONT WHEEL BEARING AND 1 ON TOP OF REAR AXLE HOUSING). I WOULD AGREE THIS IS THE BEST PLACE TO START. AS I UNDERSTAND IT, THERE IS A SMALL INDUCTION COIL IN THE SPEED SENSOR THAT DEVELOPS A SMALL VOLTAGE WHEN THE WHEEL IS TURNING. APPARENTLY, ONE OF THEM IS ERRATIC, AND ON OCCASSION, THE SIGNAL DROPS OUT EARLY ON ONE OF THESE 3 SPEED SENSORS. IT COULD BE THE COIL OR A BREAKDOWN IN THE WIRING ANYWHERE IN ITS PATH FROM THE SENSOR. THERE ARE MANY CONENCTIONS IN THIS PATH, AND IF ONE IS BAD/ERRATIC, IT TOO COULD BE THE CULPRIT. I WILL CHECK THEM ALL.

ON MY 1997, THE SPEED SENSORS ON THE FRONT WHEELS ARE AN INTEGRAL PART OF THE WHEEL BEARING AND HUB ASSY, PER WHAT I HAVE READ. AS I UNDERSTAND IT, ON MODELS EARLIER THAN 1997, THE FRONT SPEED SENSOR CAN BE REMOVED AS SEPARATE UNIT. I SEE SOME POST THAT STATE THE SPEED SENSOR CAN BE REMOVED FROM THE HUB ON A 1997 SEPARATELY, AFTER YOU REMOVE THE WHEEL, CALIPER AND SHEILD.
DOES ANYONE KNOW IF THIS IS TRUE?

I AM DIGGING INTO THAT AREA THIS AM, AND I GUESS I WILL FIND OUT FOR MYSELF. AUTO ZONE SHOWS A FRONT WHEEL SPEED SENSOR REPLACMENT, ONLY AS A TIMKEN HUB/BRG/SENSOR ASSY FOR $169...NOT SEPERATE PIECES.

I NOTICED THE LEFT FRONT HAS RECENTLY BEEN REPLACED, AS THE LEAD LOOKS BRAND NEW (I JUST RECENTLY PURCHASED THIS XLT WITH A VERIFIED 65K MILES ON IT!). THE LEAD LOOKS DIFFERENT THAN THE OEM ON THE RIGHT SIDE. WHICH ONE, IF EITHER, IS BAD IS MY DILEMMA.

I THOUGHT OF A GOOD CHECK FOR US HOME MECHANICS TO CHECK FOR A GOOD STEADY SIGNAL VOLTAGE FROM THE FRONT WHEEL SENSORS, BUT THE AWD FEATURE WOULD NOT ALLOW ME TO DO IT. THIS MAY WORK FOR ALL YOU 2WD OWNERS. I JACKED UP THE FRONT END AND PLACED ON JACK STANDS. NEXT I DISCONNECTED THE LEADS TO THE SPEED SENSORS. I HOOKED UP MY MULTIMETER TO THE LEADS. I HAVE GOOD CONTINUITY THROUGH THE COILS ON BOTH SIDES. I NEXT WANTED TO SLOWLY ROTATE THE WHEELS BY HAND, AND CHECK FOR CONTINUITY AND A STEADY SMALL VOLTAGE SIGNAL, BUT THE AWD FEATURE WILL NOT ALLOW ME TO HAND TURN THE WHEELS WITH EASE! OH WELL, MAYBE YOU 2WD GUYS CAN USE THIS IDEA. YOU SHOULD HAVE GOOD STEADY CONTINUITY AT ALL HAD TURNED SPEEDS AND SEE A LOW VOLTAGE SIGNAL THAT INCREASES WITH SPEED AND STEADILY AND SLOWLY DROPS TO ZERO, JUST AS THE WHEEL STOPS TURNING. BOTH SIDES SHOULD MATCH EACH OTHER VERY CLOSELY. I GUESS I COULD PLACE THE CAR ON 4 JACK STANDS AND LET THE ENGINE SLOWLY TURN THE WHEELS AND CHECK FOR SAME???.

I CAN TELL BY FEEL, THAT THE ABS IS KICKING IN ON THE FRONT WHEELS ONLY. I WILL CHECK THE REAR SENSOR SYSTEM REGARDLESS, BUT I DO THINK THE PROBLEM IS IN THE FRONT ABS SENSOR SYSTEM.

ALL THAT SAID, I READ ABOUT ONE OTHER ITEM IN THE ABS SYSTEM.
THE "G" SWITCH. "ON 1997 AND LATER MODELS WITH 4WD, THERE IS A "G" SWITCH, WHICH DETECTS VEHICLE MOVEMENT AND PREVENTS ALL 4 WHEELS FROM SLIDING, IF ONE WHEEL LOCKS UP (WHICH WOULD OTHERWISE SIGNAL THE MODULE THAT THE VEHICLE IS STOPPED, DUE TO ABS SENSOR)."

DOES ANYONE KNOW WHERE THIS "G" SWITCH IS LOCATED AND IS IT ON 1997 AWD MODELS?

THANKS ALL...WILL LET YOU KNOW WHERE I END UP!

 

I have a '98 Limited AWD 160k miles, identical abs problem. It turned out to be passinger side front wheel bearing. I found out that was what it was when the wheel almost fell off on I75 at 75mph. New wheel bearing fixed the abs activation when coming to a stop on dry pavement! Hope this info is not too late for you.

 

Thanks Much For The Information! I Have No Bearing Noise Or Play In Either Front Wheel, So I Do Not Believe Either Bearing Is Failing. I Do Believe The Speed Sensor In The Bearing May Be Dropping Out A Low Speeds, Or I Have A Weak Electrical Connection.

Somehow, The Low Voltage Signal Is Dropping Out At Very Low Speeds, And Not On Every Stop. The Pedal Pulsates And There Is A Strange Noise Like When You Let Off The Brakes Just Enough For The Vehicle To Move And The Pads Groan. (exactly What The Abs System Would Do If It Detected One Wheel Has Stopped While The Other Is Turning).

I Have Been Putting Up With This Rare Event For Too Long And I Will Dig Back Into Soon. Those Brearings Are Not Cheap! I Just Want To Ensure It Is The Bearing (and Which One), And Not A Weak Connection.

I Will Re-check The Condition Of Both Front Wheel Bearings Again Now, Just To Ensure I Do Not Have One Failing!

Thanks!

 

My problem started in the fall, I think, perhaps earlier. ABS activation at near stop on dry pavement. Recently (mid December) I got the ABS amber warning light on my dash. It would not be on at startup,but come on when I used the breaks. A few days later I made a trip south from Kalkaska,MI to Detroit,MI. and was cruising fine (75mph) when something suddenly started making noise in right front end. I limped about 2 miles to the West Branch exit and called for the tow truck. Had to have wheel bearing replaced and ABS problems went away. I am original owner and do have a little mechanical knowledge and I know the feel and sound on my car and I never knew it was going bad!

 

i've had ABS problems. activation on dry pavement, etc. 98 EX limited, AWD, 150k. I had the rear ABS sensor replaced around 90k, when the light went on, and it wouldn't pass inspection, and some shop took care of it. about 5k ago, I had ABS issues again, and figured it was the sensor. So i went to O'Reily's and bought the $20 sensor. Got under to get to work... and this is what i found. I had some cat convertor work done around 85k. When they redid the exhaust pipes, one of them was pinching the wire! It was about 12 inches from the sensor, along the underside of the body, but the wires were frayed! So i cut the frays and spliced the wires together, and that fixed everything.... so check your wiring too! BTW, i had just moved and some mechanic, trying to get my biz was saying he'd fix the ABS sensor for $250. Ha. it's as $20 part, easy to get to, and it wasn't even the problem in the first place!

 

Thanks for your input. I have a lot of mechanical knowledge, and I take your suggestion that a bearing could be going bad and I may not know it seriously.
On my model the bearing has 2 functions. One is to act just like any other wheel bearing and provide free and smooth rotation. The other is the integral magnet that generates the speed sensor signal. That is built into the bearing, ie you can't just change the speed sensor in the wheel bearing. My drivers side bearing appears to have been replaced recently and before I purchased this 1997 Explorer (it has only 67K miles on it!).
It is not OEM, but the wire and connector look almost new. That makes me think there was a problem there, and it was replaced. It is NOT OEM, so I do wonder if it may have gone bad prematurely??? This truck is AWD. I wanted to raise front wheels only off the ground and measure the signal voltage coming out of each wheel bearing at slow speed, to see if one was erattic, or dropping out while the wheel was still turning slowly. Being AWD, the rear wheels would drive it off the jacks...way too dangersous to try this. I guess I could raise all 4 wheels off the ground and do it, but again too dangerous to get under a car with wheels turning! So...I think I will run 2 small gage wires to each connector at the wheel bearing speed sensor connector and back probe them into the circuit. Tape them on good and run the wire under the hood, out at rear of hood and into the passenger compartment. I will get the wife to drive around while I read the voltage output signal (very small signal!) coming from each wheel. They should both read the same and produce a voltage all the way to a complete stop. I they don't, I will be able to determine which one is the culprit. I will post my results!

 

I feel your pain. I have the same problem..... I replaced both front wheel bearings & sensors and I still have the same problem.. Grrrr!