I have a 98 F150 Lariat with 108k miles. For about 3 weeks now the brakes have been doing something very strange. Whenever I am turning to the left (anything left of straight ahead) and apply the brakes the ABS kicks in and it seems like the brakes aren't working at all. I can press VERY hard on the pedal and then it seems as though only the rear brakes are functioning. The ABS light has been on (and sometimes off) for sometime now but it never seemed to have any effect on the operation of the brakes. This can happen without the ABS light coming on, but usually the light comes after this happens. Turning right and applying the brakes has NO effect, only when turning to the left of center. Had a complete front brake job (new rotors, pads, and brake lines) done about 6k miles ago. This happens especially first thing after having been parked for awhile and then taking off, but after it's "warmed up" its not nearly as bad. Have never it happen when driving at anything above 50 mph.

Have been putting up with it, but now it's scary!!!

Anyone with any suggestions/comments? Anything will be greatly appreciated (don't want to finance the dealers kids college)

Thanks,
Jim

 

Since no one else is jumping in I will give my limited thoughts.I assume 4 wheel ABS.
There are sensors at each wheel. The rotors and drums have parts ( sort of a ring shaped. deal Do a search for photos.) that the sensor reads. Check to see that the sensors are located properly and unobstructed. I have read that in rare instances the ring deal seperates from the rotor also.
This is where I would start. Good luck and let us know what you find.

 

Replaced the rear speed sensor today, but didn't take care of that problem even though the sensor metered bad. Took the drivers wheel off and think I found the problem. The lead to the wheel sensor looks to be barely hanging on...probably got dinged when they did the rotors & pads. Unfortunately I'm physically handicapped and can only do a limited amount. Appreciate the info! Gonna have to take it in for service...but I'll post the results after it's all done.

 

Hope you nailed it. Did this all start after new rotors. There is a difference between abs rotors and non abs rotors. Thanks for letting us know. Try to learn somethiong new every day.

 

Well, finally found out what was going on. My truck has 4 wheel ABS, and it turned out that BOTH the rear speed sensor AND the front left speed sensor were bad - but in different ways.

The rear one was bad and metered bad after replacement. It had been bad for over 2 months (classic example of consistent ABS light on but NO real brake problems). After replacing it the pattern and the way that the ABS light came on changed, but it did come back on, but because of the front sensor.

About 3 weeks ago the problem that was causing the scary braking situation started. That one turned out to be the front speed sensor. The "pigtail" from the sensor had gotten damaged and was creating a problem whenever the steering wheel was turned left of straight ahead. What was happening is the wiring was cracked and was going "open" whenever the wheel was turned left, but was working when the wheels were straight ahead or turned to the right. What made it difficult to troubleshoot was the fact that after driving for a short time and getting the brakes and wheels warmed up it wouldn't do it near as often. It was driving me crazy!

So, in the end there where TWO problems. Replacing the rear sensor is pretty easy - I have some physical handicap and was able to do it myself. The front one was beyond my own abilities so the dealer did it. The front sensor was $43.32 which includes the sensor and the wiring all the way up the ABS control module. It's something that if you can change the rear sensor you probably would be able to change the front one too. Just remember that after changing either one to do the routine of disconnecting the negative lead from the battery and turning the headlights on for 20 minutes before reconnecting the battery.

I appreciate all the info that I found on this site. It's great when others share the info they have to help us all? Eh??

 

Thanks for the info. I'm knocking on the wood desk now,cause so far I've never seen the ABS light on. I'll keep your findings in my back pocket in case I ever do.

 

I have a similar problem and have yet to have anyone offer up more suggestions in another post https://www.f150online.com/forums/sh...hreadid=179539 ,I tried piggy backing on. Anyway, my problem is the same as described, but when I turn right. I took it to the dealer and was told by the tech the caliper hoses were twisted. I disclosed that the brakes had been like that for ~35k miles, but he insisted that it was the problem. I paid, but was very skeptical of the fix. He noted I needed new brakes. It took me a day to recreate the braking situation, but finally figured out the problem was still there. After living with the problem for a four months, I installed new rotors with new bearing races, new bearings and new pads. The problem was still there. Then, I found this thread. I ordered and installed the right side and rear sensors. I didn't disconnect the battery, but still the problem is there. The screw was too short for the new sensor (all plastic vs. a thin metal flange), so while I was getting the screw, I went ahead and ordered the left side sensor. It will be here in 2 days, but I'm not confident that it will fix the problem. Any suggestions??

 

I saw in your other post that you replaced the front rotors...carefully inspect the tone rings, make sure they aren't tweaked or bent or anything like that. I had an Exploder that came from a Midas store that would have false ABS activation at low speeds. Midas put new rotors and pads front and rear on it, and the new rotors thing didn't dawn on me until I pulled them both off and checked with a straight edge. My guess is when they were installing the grease seals on the front, they whacked the tone ring with the hammer and bent it slightly, widening the air gap between the tone ring and sensor.