Hi.
I just recently bought my first Ranger.
03 2x4 3.0 automatic.
Having some heavy rain and wet cold conditions on the West coast of BC.
I had the front brakes lock up very easy.
Too easy for my liking.
Brakes feel a bit spongy, but also figured the older all terrain tires that came with my truck might be old and hard and lousy in the rain.
So being winter, I put on some new winters.
Much better in the wet, but as once before the brakes in the front locked up easy, even on dry pavement.
Then one of my back wheels locked up, this all under slow driving.
The brake pedal is right up top when this happens without much pressure applied.
Other times they feel spongy.
No ABS light.
The ABS has kicked in under harder wet braking, but lock up can be intermittent.
Can this be an air in ABS issue?
Any input would be very much appreciated.
Thank you.

 

It's possible it's an ABS issue but not most likely cause.

When you have time jack up front wheel(s)
Spin them to get an idea of how much drag there is, there will be some, pads always rub rotors a bit.
Start engine
Apply brakes a few times, leave engine running
Spin wheels again and see if drag has changed, i.e. pressure is not being released fully

If brakes drag too much they heat up and get "grabby"

With engine running get down under dash drivers side and push brake pedal down by hand.
The brake pedal rod pushes open the Atmosphere Valve in the power booster(inside cab part), this valve lets in outside air pressure which gives you "power assist" braking.
If Atmosphere Valve is leaking then it is like you are "riding the brakes" all the time even though pedal is up all the way.
You will hear the air flow when you push down on the pedal, make sure you do not hear it when pedal is up.
You may see a vacuum hose down there as well, that's the backup cut off for Cruise Control when brakes are applied, it drains the vacuum used by the cruise actuator

Replace Master Cylinder and bleed system, not expensive

 

Thank you RonD.
I do remember when at one time I hit the brakes hard that the RPM went up.
thought about a vacuum leak.
I will check the booster. I do not have cruise control.