Another Stupid ABS Issue

[Slug]

Alright Kids....I must be missing something obvious. For a few weeks now, when I back out of the driveway I get the buzzing in the brake pedal like I'm sliding on ice, but it's summer in NC. Then, the ABS light comes on and stays on. And, maybe it's my imagination, and I don't know if it could be related, but this trucks shifts HARD since it's been doing this light thing. I changed the axle sensor and it didn't make a difference.
99 Ranger, 4x4, 4.0, automatic trans.... new motor, new transmission, rebuilt transfer case, all 5,000 miles ago with no issues. No runs, no drips, no errors. New front brakes, rears are good. I don't off-road it (yet).
I took it to Auto Zone, and no error code showed up even tho the light was on in the dash. I don't know what else to check at this point

 

[Roert42]

If that light is on there are codes, it’s just that the code reader they have at auto one can’t read and codes on a ford.

 

[Uncle Gump]

99 should have 4 wheel abs. Front wheel speed sensors are part of the unit bearing. I've seen a few times where a front wheel speed sensor will fall off at low speeds... while the remaining sensors will still be moving. That will cause the abs to activate. The real way to diagnosis it would be to bring up live data and watch the speed sensors while driving. The poorer man's way is to see which way the vehicle pulls when the abs activates. If the RF sensor is falling off... vehicle will pull left and vice-versa.

 

[RonD]

ABS codes are "C"(chassis) codes, most readers only show "P"(powertrain) codes unless "asked" or they can't read them

OBD2 has these types of codes
P = powertrain codes, engine and transmission codes
B = body codes, cab electrical codes, i.e. airbag, seat belts, even wipers
C = chassis codes, usually brakes and traction control
U = network codes, the data network that connects modules together

 

[funguy26]

99 should have 4 wheel abs. Front wheel speed sensors are part of the unit bearing. I've seen a few times where a front wheel speed sensor will fall off at low speeds... while the remaining sensors will still be moving. That will cause the abs to activate. The real way to diagnosis it would be to bring up live data and watch the speed sensors while driving. The poorer man's way is to see which way the vehicle pulls when the abs activates. If the RF sensor is falling off... vehicle will pull left and vice-versa.

ABS systems will disable themselves it has have a fault code related to sensors, pump motor, or valve assembly. if it's a network related code the system should work on it's own.

 

[dvdswan]

Is there any oil spots on the tires? or on the ground where you back out of the driveway?

 

[Uncle Gump]

ABS systems will disable themselves it has have a fault code related to sensors, pump motor, or valve assembly. if it's a network related code the system should work on it's own.

That isn't entirely true. My truck had a faulty wheel speed sensor and the ABS system still functioned (the sensor would stop sending wheel speed data below about 5mph). It would be true if during system self check the ABS module saw a problem... set a fault code and turned on the warning indicator.

 

[funguy26]

are your tires the same size?

Alright Kids....I must be missing something obvious. For a few weeks now, when I back out of the driveway I get the buzzing in the brake pedal like I'm sliding on ice, but it's summer in NC. Then, the ABS light comes on and stays on. And, maybe it's my imagination, and I don't know if it could be related, but this trucks shifts HARD since it's been doing this light thing. I changed the axle sensor and it didn't make a difference.
99 Ranger, 4x4, 4.0, automatic trans.... new motor, new transmission, rebuilt transfer case, all 5,000 miles ago with no issues. No runs, no drips, no errors. New front brakes, rears are good. I don't off-road it (yet).
I took it to Auto Zone, and no error code showed up even tho the light was on in the dash. I don't know what else to check at this point

 

[19Walt93]

ABS systems will disable themselves it has have a fault code related to sensors, pump motor, or valve assembly. if it's a network related code the system should work on it's own.

No, they won't.

 

[19Walt93]

Step one: leave Autozone immediately and find someone qualified to test it. Their parts are bottom shelf and their "diagnosis" isn't good enough to be a joke.