I just got back from 2 weeks vacation and I had to move my 1985 300 TD around in the driveway. We didn't take the car, it had been sitting for 2 weeks. So when I moved it, the brake pad wear indicator stayed on. I had the brakes done a few months ago so I know the pads are good. I assume that one of the calipers is stuck? I am hoping it will become unstuck. I have to drive the kids to school in the morning.

Should I risk it?

If the light stays on should I not drive it?

Thanks

Peter

If the light just came on it will surely be ok to drive for a day or two until it can be checked out. If the pads are pretty new there may be a wiring problem. The light can't tell you if a caliper is stuck or not. Yes, a stuck caliper can, among other things, wear out a pad prematurely.

One thing that can light the light even though the pads are fairly new is if the rotors are worn and there is a significant lip at the edge. This lip reaches past the "good" part of the pad and touches the sensor before the pads actually wear out.

I have had a sensor wire to short out on the pad retainer spring. Even though they are insulated, I like to dress the wires so they don't touch anything metal as they make their way to the connector socket.

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

I would guess bad sensor wire or wiring by brake job guy, or they left it off altogether which would cause the light to be on immediately following the brake job and remain on until wired correctly.

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85 300CD Turbo "Das Polluter" 230K sold for $3,000

98 BMW 323is

You're not taking much of a risk driving the kids to school. Its probably the sensor, but if the rotors are warped, they'll have to be replaced anyway. The family truckster will be fine.

I didn't realize the sensors do not work on the back brakes. New back pads and rotors were a recent addition to SL. $350.00 later, lesson learned.

__________________
1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

My 83 only had front brake pad sensors, but my 87, 92, and 2002 have them front and rear. An interesting thing is that on the 2002 S class there is not a sensor in every pad. In fact, on the rear there is just one sensor on one wheel, PERIOD!

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

Damned MB cost cutting accountants.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Considering that the wire is needed to complete the circuit for the light, how is the light going to illuminate it the wire is not installed?

Lets make sure were talking about the right light. It is the wear sensor light, A round circle with 3 short dashes on each side. NOT the RED brake light.

http://www.peachparts.com/Wikka/W123BrakeWarningLights

If it is the wear warning light then go ahead a drive it. It could be a couple of things. the harness could be going bad and shorting out the wire. The sensor was not replaced and is hitting the rotor. Driving it will be OK for a while as long as you know the pads are OK.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

No kidding. Sometimes the pads will wear at different rates too....especially on a car with traction control like the new ones have....though you could argue that the pads will wear "close enough" to the same to not cause a problem, and that less sensors means less potential places for the circuit to have issues or fail. I'm still a fan of a sensor on every pad/wheel though.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

If the pad wear light is on, it could be a sensor come loose, or maybe a harness failure, being recently replaced. And, no it doesn't let you know of a stuck caliper. Inspect to find out for sure.

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83 SD

84 CD