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Additional master /slave brake cylinders under the hood?
So my brake pedal slowly goes to the floor when braking, but the brakes firm up if I pump it 3-4x when coming to a red light. I was going to replace the master cylinder on my 94 2wd 12v. As I look under the hood, there are additional cylinder apparatus's tied in with the MC, maybe as a towing booster of some sort? Can't say I've ever seen these before; anyone know what they are specifically? Can't find anything on napa or advance auto etc. to replace them with. Not sure if they might be contributing to my brake problem or not. Any help would be greatly appreciated- thanks! 2 additional junction blocks under the master cylinder
The first block in the hydraulic path from the master cylinder is the combination valve (and brake warning light sensor - it can be considered as containing a sensor). After that, the block (with the multiwire connector) in the pathway to the rear brakes is (as Sixslug said) part of the ABS mechanism - it is the dump valve for RWABS.
Do you have a factory service manual (FSM)? Or a Chilton or Haynes manual (even they will show the brake-system components)? There's nothing like the FSM for learning how the systems work on these trucks.
