Hey all. Need your help please. Wifey reported that the ABS light came on my family's grocery-getter (a very clean and tight '97 C280). Went out and checked. Here are the symptoms. Maybe you can help me fast-track the problem:

* Key in. Foot on brake pedal.

* Key to position #2 (pre-start). All idiot lights come ON.

* Key to position #3. Engine starts instantly. All dash lights go OUT, including ABS.

* Foot OFF the brake pedal. ABS light comes ON. (Note: if I start the engine with foot OFF brake pedal, ABS light stays ON.)

* Checked battery connections (disconnected for 10 minutes), then brake fluid, brake lights, fuses, and inspected (but did not replace) front wheel sensors, brake pedal switch, rear differential speed sensor, multi-pin connectors in trunk. Unplug, inspect, plug back in. All look clean and tight.

* Drive the car. Everything works ... except and CRUISE CONTROL. That has to be a clue.

* Note: the same day Wifey also says the driver's seat belt chime/warning isn't working -- the one that warns you if you drive without being buckled in. Is there a connection? Hard to see the relevance.

Any ideas? Much obliged if you can share them. Thanks a million.

 

The first thing to do would be to have the codes read. An ABS light indicates a stored fault code much like the Check Engine Light does.

 

This is an easy one. One of your abs sensors at one of the wheels has died. This picks up speed impulses from the hub, which explains why your cruise control has gone. You will need a dealer diagnostic machine or similar to tell you which one. It is an easy fix... unbolt, unplug replace. Same symptoms on my S32o cdi, except my steering went to default (lost full, assistance) and engiine went into limp home. New sensor cost £75, sure to be cheaper your side of the pond!

 

Okay, thanks. From what I hear, besides the front wheel sensor, other common culprits are the rear differential speed sensor and the brake pedal switch.

Changing all three sensors is pretty straightforward, but the brake pedal switch looks to be a hassle to remove (I wrestled with the hood release lever). The brake lights work, so I assume the switch is okay?

 

Follow-up: You were right. I had the codes read by my local MBZ wrench. Apparently, the culprit is the brake light switch. Time I buy an OBDII reader!

 

Hi. Thought you may be interested in / able to lend advice on my ongoing problem: an intermittent ABS light in my '97 C280:

Action 1: Two weeks ago I had a MBZ mechanic replace the brake switch. Actually, twice. First one was faulty! It got stuck in the "on" position. Drove it like that for 30 miles or more.

Result: Although the ABS is off when I start the car, it will comes back on a few miles later. It's not a repeatable problem, but sometimes it comes on after a stop sign/right or left turn.

Action 2: Last week I had the error codes read by the same MBZ mechanic:
- ABS: "C-1200 stop switch"
- Engine: "P1584 stop switch"

What? It's a new swtich in there!? The mechanic checked the switch and said it's working fine. Note: Since the first stop switch had been stuck "on" for a while, I changed all the brake light bulbs because of the excessive heat (one was black inside). Just a precaution in case a bad bulb can have an effect on the ABS system (a stretch, I know).

Result: Drove it all week ... same problem exactly. Looks good for a while, then it comes on. Typically while going slow and turning sharply. IS THIS A CLUE?

Action 3: Today, I changed both front ABS wheel speed sensors.

Result: Oddly, the light was on when I started the car this time. It went out after about 100 yards of driving. Then, as usual, a few miles later, while navigating the neighborhood streets, it back came on.

The question: Should I have reset the system when I changed the sensors? Do I keep moving, changing the REAR sensor next?

Thanks for any advice.

 

ABS light problem is finally. Here's a review of my findings.

First Mercedes "specialist":

- First new brake switch installed was faulty. It failed thirty miles from home. I drove back not knowing my brake lights had been on the entire time (remember this part).

- Second new brake switch installed. Seemed to fix the problem -- for a while. Then the ABS light came on again. Same basic problem as before. Codes read "brake light switch." Weeks later I started getting a bulb warning light. Replacing the brake light bulbs turned it off, but the problem would surface in a few days.

The shop showed no real interest in helping further. They said: "Make an appointment next Thursday. We'll have to keep it for a few days -- maybe we can find the problem. Probably an ABS control unit."

New Mercedes specialist -- a real one:

- Called a new mechanic. "Hans" asked for me to come over immediately. Took the time and interest in the car. Spent an hour right then to read the codes, drive car, re-read the codes. It came up every time "Brake light switch." He put in a third new switch. I also mentioned the brakes lights had stuck on for thirty miles. We inspected the rear multi bulb housings very closely. They appear to have slightly warped/burned areas where the bulbs are held. Possibly this now causes a high resistance situation, hence a bulb out warning when there isn't one. We replaced both units and installed all new bulbs.

End of problem! I have driven the car for about 150 miles and all lights stay out.

The problem got complicated when the fist shop installed a questionably "new" first switch. I say this because they showed it to me before they put it in. The bag had already been opened. My sense told me it's not 100% new. It was just a hunch, but look at the result. Keep this in mind when your ABS light goes on and you think replacing a suspected part with new instantly solves the problem.

 

Wow, my 97 c280 just started doing that too a few days ago. The ABS light came on and now my cruise control isnt working.

 

Glad my offered anecdote of the prescribed antidote can be of help to you!

 

Thanks for posting this. I just started observing this issue with my 95 c220. Thanks!

 

Hi,
I am having intermittent ABS lights on my 1996 C280, and 2005 E350.
The Trouble Code for the 2005 is "C225C", which I managed to find it listed by someone as a "ABS Intermittent".

Anyone have a good source to recommend for looking up trouble code descriptions?
I have seen some listed here in the wiki for some cars, but mostly they are Powertrain "P" codes. I would like to know of a complete list, and description...

Thanks.

 

@ Fiftymoons (Also, maybe taimyshukah but your post is 10yrs old...)
And any one else who is having intermitent ABS light on their W202.

My 96' C280 started with intermitent ABS light that in 8 months since first appearing, went from a monthly light showing (which reset after parking the car for a few hours -cool down-) and got slowly worse till the last two months was coming on sometimes daily (but did a couple times go away for up to five days)..
Trouble code gave me Pump and pump relay... I was not aware of the relay... changed it, and problem solved (had a bit of corrosion on one leg; sealed unit, possibly internal green stuff too..)

Always try the relay before going for anything expensive (relay is cheap as speed sensors are, and easy to change).