Unable to bleed Rear brakes

[liteofa1000suns]

A bit of a complex story, I hit a big water puddle that caused my ABS, DSC, Brake lights to come on. After further troubleshooting I deduced that the ABS module got water in it and shorted out. The bigger problem was it caused the ABS pump to "push" and not retract as soon as the car was turned on. I got stuck on top of heavenly in the middle of blizzard conditions. I ended up disconnecting my ABS module cable to drive down the hill. Ever since then, I havent had rear brakes...at all. I pulled apart the ABS module with help from your Xoutpost threads (thanks guys) and cleaned and dried it out. Ive reconnected it and all electronics are fine, but still no rear brakes. I bought a power bleeder and am still unable to bleed the rear brakes. Have I narrowed it down to replacing the ABS pump? ...which I hear is not cheap. Or do I need to crack the brake lines at the ABS module to let the plunger reset?

[JCL]

I think your first step is to try a full bleeding procedure. You can't do that by just cracking a line on the ABS module, as there are valves in there and they hold trapped air. The correct procedure is to bleed it manually (or with a power bleeder) while the BMW service computer is hooked up to it. The computer is used to run a service program and cycle all the valves, so that you can get the air out. A dealer can do this procedure, or a good independent mechanic with the right tools (GT1 or similar).

If the bleeding procedure does not work when done as described above, or if the BMW computer shows faults on the ABS control module, then replacing that module would likely be the next step (again, followed by the full bleeding procedure).

Edit: Here is a link to a post with some discussion on this:

http://www.xoutpost.com/655315-post7.html

[admranger]

Activate (safely) the abs on some snow/ice/water/gravel/whatever. See if the rear brakes get working again or if there is a change in pedal feel (i.e., the air bubble moved out of the abs unit and into the lines).

Activating the abs on the race car after a bleed was standard, just to keep things moving through the pump.

[Wayne's World]

If it comes down to replacement, check out BBA Reman for a re-manufactured unit and save some $$.

[liteofa1000suns]

Thanks guys. I did try to power bleed all lines, and when I crack the two rear...nothing comes out, nothing. I tried to activate the abs on a gravel road, but the pedal is too soft. Is there a way to jumper the abs pump using the relay? I read a thread about it a while back but cant seem to find it now.

[JCL]

Originally Posted by liteofa1000suns

Thanks guys. I did try to power bleed all lines, and when I crack the two rear...nothing comes out, nothing. I tried to activate the abs on a gravel road, but the pedal is too soft. Is there a way to jumper the abs pump using the relay? I read a thread about it a while back but cant seem to find it now.

There is more than one solenoid and valve in the ABS controller and they prevent proper bleeding. Using the BMW tool cycles all the ABS valves while you bleed it. I think that is what you need to do first.

[admranger]

Originally Posted by JCL

There is more than one solenoid and valve in the ABS controller and they prevent proper bleeding. Using the BMW tool cycles all the ABS valves while you bleed it. I think that is what you need to do first.

I agree. You have a bigger problem than a simple DIY pressure bleed can fix.