Sigh. My 1994 E420’s ABS light is coming on more frequently. I’ve cleaned the front sensors and it helped for about a week, but now the light is coming virtually every time I run the car. I haven’t checked the 3rd sensor back by the differential….I really hope it just needs cleaning. I’ve checked the fuses in the computer box and everything. I have no idea as to what I should do next.

ANYWAY, on to the subject of this thread. My master cylinder could be on the fritz. As I step on the brake pedal there is a little “chirp” or “squeak.” Almost like a squeaky hinge on a door or something, nothing too loud or anything, but there nonetheless. The pedal never felt strong or hard like it does in my 1990 300E. The E420s pedal feels kinda mushy even though it had new pads.

Is there anyway to know for sure if my master cylinder isn’t working at full capacity? Could this even remotely be connected to my ABS light problem?

What does it take to change out the master cylinder? I do all the work on my cars but I’ve never had to deal with a master cylinder. Will any bleeding be involved…..and I’m not talking about my busted knuckles.

For what it's worth, my pedal creaks also when I step on the break. I have even been accused of passing gas, because of this noise.
semi-related: my abs light also started to come on intermittently....Turns out it was the breaklight-switch going bad.

hope this helps..

-Larry

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

yeah that sounds about right. My coworker one time was like "are you okay?" - it was funny.

Anyway tell me more about this brake light switch. where is this switch?

The brake light switch is right above the brake pedal (or real close to it). It activates when you press the brake.

I believe that it is used to signal the ABS that it's OK to activate, as well as turn off the cruise control.

I was getting an ABS light and replacing this switch fixed the problem. Takes about 5 minutes. Or 15 minutes if you're outside in the dark (like i did).

This is the cheapest and easiest 1st step towards fixing your problem. i think that the part is around $15.

Regards,
Troy
1995 E420

If the brake light switch is bad wouldn't it give a code?

You might try looking at your brake booster. When my master cylinder went bad the pedal was still firm, it just slowly sank to the floor. From what I know when it's mushy it's the booster.

__________________
1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

so get this. I just now realized that when the ABS light is on.....my cuise control is OFF. Sounds suspicious.

Guess I'll just go ahead and try the stop light switch - but the thing that makes me wonder is the fact that my brake lights work. I would assume if the stop light switch was dead or dying, the lights wouldn't work.

Yeah, you would think that if the switch is bad, that you probably don't have any breaklights. But... I can assure you, that my brakelights worked the whole time.

Good Luck!

-Larry

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

If your cruise control is Inop when you're getting the ABS switch - then it's the brake switch. I had the exact same failure. Fortunatley, this is a quick and easy fix.

Troy
1995 E420 77k

well, I just changed the stop light switch. We'll see what happens over the course of the next week or so. It better not friggin' come back on!!

thanks for all the help guys. Its been informative.