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@99brokeTahoe Moved you here.
Welcome from Queens NY.
Welcome from Queens NY.
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I've never had a problem bleeding brakes like this before, unless there was failure in the system, and I had hard time getting the portioning valve centered. Everything is new within the last year or two as far as the brakes go. I did try my Tech2 to do the automated bled procedure. It wouldn't because it had speed sensor codes. I cleared the codes, then it worked. I did some research on the codes, and found a TSB on the speed sensors, that sounded like the problem I was originally trying to fix. After reading this TSB, I think it was the ABS trying to activate, but not like it does at speed in loose gravel. About a month ago, I replaced both CV axles and wheel bearings. Both axles, bearings, and bearing hub bolts were difficult to remove. Rust and age I guess. I even replaced the hub bearing bolts with new, and coated everything with antiseize. The TSB talked about dirty wheel speed sensors, and rust on the mounting surface causing the low speed ABS problem. Last night I pulled the front wheels, rotors, and calipers to check the sensors. Both sensors, and the reluctor wheel teeth had antisieze on them. I think that this is what caused my original problem. I cleaned everything, put it back together, did the automated bled again. The pedal doesn't feel any different, and I plan on bleeding all 4 corners today again. What kind of plugs would you use in the master cylinder? Maybe I'm overcomplicating it, but I thought that they were an odd straight metric thread with an odd bubble flare, is the reason I ask. Thanks for all the replies.Best fix I found on OBS trucks is to use a NBS MC, makes the pedal feel like you're actually going to stop. I must just be lucky but I've never had any problem bleeding these brake systems and I do have a scan tool that can do the ABS activation but never see any difference if I do it that way or without.
Test on a booster is to pump the pedal multiple times with the truck off. Then while holding pressure on the pedal start the truck and you will feel if the booster is working as the pedal will drop.
The simple test on a MC is buy 2 plugs for the MC, thread them in and step on the pedal. This will let you know if you have air in the MC or just how high the pedal can be if the system is good. Of course every wheel's brakes should be inspected and all of the lines especially on a 25yo truck.
Old and new push rod, side by side. Looking back, I think I caused the original problem when I replaced both front hub bearings, and contaminated the sensors and tone rings with antisieze. I thought it was something binding in the linkage, MC, or booster, but it was just ABS coming on a slow speeds. I think the problem is in the ABS module now, but I'm going to try and bled it again. Thanks for the reply.Did you get the little rod that goes into the brake booster out of the old one and install into your new one? Is your brake light coming on? I suspect you still have some air trapped at your ABS manifold because you didnt use an auto bleed feature of a bidirectional scanner. Seen this scenario right her on this forum so many times.