Mr.T

That slight mushy feeling may be that ABS needs it's special bleed procedure. A buddy of mine had similar for a couple years, and had bled the brakes numerous times. He mentioned it while we were replacing an axle, and since I had my scan tool with the ABS bleed function we gave it a try -- No more mushy pedal. Side note, regular bleeding is required after the ABS bleed function to completely remove the air (the scan tool should notify).

4Geaux

I'll have to check that out. Thanks.

4Geaux

4Geaux

Stretching out at Barnwell

SoK66

Mr T, what scan tool do you have? I'd like to get one with the Mopar ABS bleed function.

Mr.T

It's an OTC 3210, paid a bit over $200. Just did a quick search and the price variation is crazy -- $212 to $360.

SoK66

Thanks, I'll check it out.

Rednroll

I'ld be interested to learn more details of how this is performed with the scan tool. It also has me curious to find out if my BlueDriver OBD2 scan tool has this type of capability or not since it supports ABS.

Mr.T

After selecting ABS Bleed in the menu, the scan tool gave instructions and did some magic with the ABS pump/solenoids. Regular bleeding is performed first if not already done, then the scan tool runs the pump and solenoid valves a few times, reiterates which wheel to bleed next, and waits for a key-press to continue.

SoK66

The ABS motor/pump unit (module) is between the master cylinder and the calipers. Each wheel has a circuit within the module that's normally closed tight by a spool. These spools open & close rapidly to balance braking and prevent wheel lockup and vehicle yaw when ABS / ESP(or C) is activated. The scan tool routine opens the spools one at a time and holds them open so any trapped air can be expelled. The routine has you bleed the brakes three times, first time with spools closed to get any air out of the basic system, then with spools open consecutively to expell and air in the ABS module, then a final bleed to remove any remaining air that might have been purged from the module and still trapped in the basic system.

In general if you just open the basic circuit to, for example, replace the flex lines, bleeding the ABS module isn't required. I even replaced the stock master & booster with the Mopar BBK units and didn't need to bleed the ABS. However, if you were replace the ABS module, or leave the system open for any length of time then beeding ABS is essential.