I recently aquired a MY1994 & up Maintenance Manual (124,129,140,202 cars). In it I see that to bleed or flush the brake system on cars with ASR and later versions of slip regulation requires the use of the impulse counter. My question is: is this absolutely necessary? I have a 1995 C280 (which I don't think is effected by this as it does not have ASR) and a 1999 E430 (which of course has ESP). I recently flushed the E430 using my normal procedure, but at the rear the fluid flowed very slow (I use an EZE-BLEED at 20 psi). Do any of the techs on the board have any suggestions on a "home-made" impulse counter? It would be nice to get an overview on what they are trying to accomplish using the impulse counter. I assume there are valves and perhaps an accumulator in the system that need to be flushed or bled. Any tutoring would be appreciated.

I have never had to use an impulse counter. I think what it is used for is to put the system into a diagnostic mode so there is no possibility of the system activating and sending pressure your way while bleeding.

There is a system accumulator. You can bleed it from a service port on the pump.

Thanks, Benzmac. I looked carefully at the E430, but I can't find a bleed port on the pump unit. At this point, I am going to assume that I am performing an effective flush by pressure bleeding the system at the calipers. I flushed about 500ml through each caliper. I didn't have any problem with the pump energizing and pressurizing the calipers while I bled the system. I did have the ignition off, but without any wiring diagram I don't know if that shuts down power to the pump. If you have any other hints please forward them.