I think my ABS module is going out but am new to this type of system. When braking I get a pull to the right indicating the driver brake not grabbing. I also have a soft pedal. I’ve tried bleeding the brakes both manually with suction, and with the ABS relay hack. I cannot get fluid to the rare passenger or the front driver. On the ABS module those are the two on the right side of the abs block. I have “bench” bleed the master cylinder while on the car and have fluid getting to the abs block. Through messing around with all four lines when I remove the lines on the left side an actuate the module using the relay hack fluid moves, but not on the right side. Can half of the module go bad? What else can I be missing?

Bleeding in California

 

Cool handle. Can’t help you on the brake problem though. Dealing with one myself that I can’t figure out.

 

Bump, and thanks.

 

The ABS unit is 'pass through' for brake fluid from the MC...a safety feature...so if the ABS pump fails, you still have brakes...and so that you can't over pressurize or under pressurize the caliper pistons...but it depends usually on valve position in the ABS unit. The motor operates all the valves/pistons, but it is possible to have a leaking or stuck valve. If the valve is stuck in a 'non-pass through' or 'partial pass through' position, then you can have unequal caliper piston pressure and pull to opposite side, or dragging from unreleased over pressurization .... ......

or MC has a bad piston seal...

or rust in your brake lines....

or stuck caliper piston....

 

I have gone through the rest of the system and am sure its not in the master. I have also blown down the lines so I know they are fine too. I can see the problem at the ABS module. I just don’t have enough knowledge on the piece of equipment to troubleshoot it. Does anyone have a diagram of the block internals?

 

Wabco Meritor is the manufacturer of the ABS system, and is very secretive to show its inner workings as we are soooo good at tampering/modifying which can cost many lives. I had downloaded from the net what you are asking and have it archived on some other hard drive; cannot find it on the net now.
Try searching with the part number of the modulator + diagram. Abstain from guessing, experimenting, tampering. Use it for learning only.

 

used units are about 100$, new ? 1400$. I think you can purchase the valve block for like 600$.....I would look for a rust free used complete unit....and rewire the shuttle switches before replacing....

 

I just got back and installed one from a pick a pull. Half off weekend. Installed bled and on the road in about 20 min. Works great. Was able to pick up a few other thins while I was there. If anyone is in the Fresno area the iPulluPull has a 2000 with the transfer case still in it. If you pull it out this weekend you can get it for about $75. I don’t have CDL but also didnt have the time to pull it. As far as the ABS I took the whole unit including the shuttle valve. I used my existing shuttle as I have already done the “fix” to it.

 

I presume you mean the shuttle valve switches.