Hey all. Need your help please. Wifey reported that the ABS light came on my family's grocery-getter (a very clean and tight W202 C280). Went out and checked. Here are the symptoms. Maybe you can help me fast-track the problem:

* Put key in. Foot on brake pedal.

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

* Twist key to position #3. Engine starts instantly. All dash lights go OUT.

* Foot OFF the brake pedal. ABS light comes ON instantly.
(Note: if I start the engine with foot OFF brake pedal, ABS light does not go OUT.)

* Drive the car. Everything works, including brake lights ... except CRUISE CONTROL.

* Checked battery connections, brake fluid, fuses, then 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. Test drive. No change.

* Note: the same day the ABS light came on, Wifey says the driver's seat belt chime/warning stopped working. Is there a connection? Hard to believe, but I will also investigate a faulty/sticky seat buckle and the wiring under the seat.

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

PS: From what I have learned, the common culprits are:

1 - rear diff speed sensor
2 - front wheel speed sensor
3 - brake pedal switch

The first two are straightforward, but if the brake lights work, is the brake pedal switch okay? Seems a major hassle getting the old one out. The hood release gave me a lot of trouble.

You may also have a low voltage condition
Have the battery/changing system checked.

Follow-up: I had the codes read by my local MBZ wrench. Apparently, the culprit is the brake light switch. Ugh, looks like a PITA to get to in the foot-well. And 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.

If the fault codes for the Stop Lamp Switch re-occur, then the problem lies with the switch, wiring, or the control module. The wiring should be checked for short circuits to power, ground, and other wires. This is a simple job that only takes a few minutes. Don't waste anymore money until you check the wiring. Good luck