Mercedes-Benz Forum banner

Likely SBC Issue

1K views 5 replies 4 participants last post by  mersum1es 
#1 ·
This morning my 04 E320 4matic ran just fine. This afternoon when I started the car, a red reduced brake warning and brake system malfunction warning illuminated the dash, coupled with an ESP warning. The lights then went away.

I let the car warm up (it was 30 degrees) a bit. I drove a hundred yards and braked to a complete stop twice with no problem. Pull on to the main road and all the warning lights came back. I glided into the adjoining parking lot with zero brakes.

Two months ago, I got a low brake fluid warning and filled up with the correct fluid. Today, after gliding to a stop, I noticed the brake fluid was below the min line. I filled it back up to just below the max line. I pumped the brakes a couple times to hopefully reintroduce fluid in the system. I then turned off the car for several minutes and restarted and let the car warm up some more. Warning lights reappeared.

I then notice the SBC pump would vibrate and make a groaning noise every five seconds (I timed it). It even would vibrate after the car was turned off. The auxiliary battery was replaced a year and a half ago, but I do get the "aux functions not available" for a minute or two now and then. I will be unable to get the codes, as I am not putting that thing on the road. What is my next step?
 
See less See more
#3 ·
System cannot maintain pressure, either it is hydraulic accumulator like said above, or then you have a leak in system since it keep loosing fluid. Check rear brake pipes, they are prone to rust where they go under plastic covers. Your pump will reach it's 'service limit' fast if keep it that way (I am not talking about resetable counter only)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top