I have had the same ongoing problem. Here is what caused my problem. Replaced Brake rotors, pads took the truck for a test drive and the ABS would engage at low speeds. I thought it was the Master cylinder after I received a few replies to make sure I bled the brake systems. I bled until it could bleed no more. Found out that that exciter ring was not true and had rubbed on the RF wheel sensor. I took the rotor off used a piece of wood and tapped the exciter ring straight. Ordered a new wheel sensor from O'Rileys for $41 and change and the problem is fixed. A crazy problem but thanks yto everyone for their inputs
solar

I have just developed this exact issue, ABS engages on left wheel, therefore truck pulls to the right when almost at a stop. I will replace the left ABS sensor and let you know how it goes. Anyone know if it is easy to get to on 2wd trucks??

__________________
http://i.imgur.com/IvtzY.jpg

I must provide the final update. I posted my last update believing the wheel sensor was the fix. Well it was not. I replaced the right front ABS wheel Sensor and took the truck for a test drive knowing I had foxed the problem. As I approached the stop sign the truck slowed and at about 5mph the ABS engaged again. I was very distraught, I had been neaten by a Mazda B3000 brake problem. I was very disappointed and made some calls on Saturday morning to see how could get the truck in and what they would charge to look at the truck. Dobbs Auto wanted $99.99 to look at it and that would not be deducted from the total if they found and fixed the problem. So I thought about how I got here and decided to see if one om original Rotors could be turned they were in rough shape but maybe one could be salvaged. O'Rileys did it for $13.00. I brought the Rotor home and decide I would try one last thing and put the original Rotor (just repaired) on the right front wheel. Well guess what the Truck brakes normal. I did some measurements on the "New Rotor from Advance Auto parts was defective. the Exciter ring was installed to deep causing the ABS to receive erratic voltages from the Right front wheel which caused the ABS to engage at low speeds. So here is my what I replaced during this trying event.

Orginal Brake job 2 rotors and Pads.

After problem developed I replace the Master Cylinder, The ABS Sensor and had the original Rotor Turned so it could be resued.

I can pull the wheels , caliper/and holder bearings and sealsin about 8 minutes. I had the wheels off at least 20 times. I bleed the entire brake systems twice, someone said I might have air in the ABS system. The Chilton's manual lacks a lot of vital information about a 2001 2wd Rangers/Mazdas.

So what Did I learn. Cars are a pain in the _ss but go back to the start, with what you did and when did the problem arise. Don't chase phantom problems. I introduced the brake problem with the NEW ROTOR. Just because a part is new it can be the problem. Look at everything objectively. Sometime the problem is right in plain sight.. I thank everyone who respond to my requests for help.

Have a Wonderful Christmas and New Year,
Solar in the St Louis Metro East: