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  #1  
Old 05-24-2006, 01:18 PM
skiier3_9's Avatar
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W124 - Brake Pad Wear Indicator Light - Problem

On my 94 E320 (w124) the brake pad wear indicator light has been on since I painted my calipers - I've checked the pads and they're good so I've been ignoring it for awhile. Today I investigated further:

- unplugged 4 front sensors -- light still on
- unbolt the 2 front sensor holders -- light off

SO - I looked at the sensor holder and it appears that it makes electrical contact with the caliper itself.

- clean passenger caliper at the contact location and clean contact
- attach sensor conector and 2 sensors -- light still off
- repeat on drivers side -- light comes back on

Can someone tell me how this circuit is suppose to work? Why is the light on (even though the two sensors are unplugged at the drivers side)?

Thanks!!

EDIT: See attached photo - #5, 10 and 15 are the parts I'm talking about.

My retaining screw is quite rusted - I think I'll change that and see if it makes a difference.

EDIT2: Changed the screw - no change in the symptom. I think i'll trace the connector back and see where it leads.

Attached Thumbnails
Brake Pad Wear Indicator Light - Problem-brake_sensor.jpg  
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Last edited by skiier3_9; 05-24-2006 at 03:36 PM.
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Old 05-24-2006, 03:48 PM
sixto's Avatar
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If there's any path from the sensors or wiring to ground, the warning light will come on. Maybe one of the wires has insufficient insulation.

Also I think the same warning light is used for brake fluid warning. Check the fluid level.

Sixto
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  #3  
Old 05-24-2006, 03:55 PM
skiier3_9's Avatar
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Fluid level is great - I think you're right about the insulation. I'm going to trace the connector back and see if I can replace it.

Heres the weird thing:

With the passenger side front only attached correctly (drivers side disconnected) the light is out. But - I took my multimeter there and the sensor connector (the pin) has continuity to ground, and it has continuity to the retaining screw - electrical contact to the caliper. So - why doesn't the light come on with the passenger side attached??
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Last edited by skiier3_9; 05-24-2006 at 04:06 PM.
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Old 05-24-2006, 04:39 PM
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Heres the weird thing:

With the passenger side front only attached correctly (drivers side disconnected) the light is out. But - I took my multimeter there and the sensor connector (the pin) has continuity to ground, and it has continuity to the retaining screw - electrical contact to the caliper. So - why doesn't the light come on with the passenger side attached??[/QUOTE]



Seems like this happened to my sons 300e....with both sensors attached the light was on....so i go out and get new sensors. i decide to pull the passenger side to look at it...the light goes out...

never installed the new sensors.... i'll change pads way before they wear out.... i don't mess with tires or brakes...
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1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



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  #5  
Old 05-24-2006, 04:57 PM
skiier3_9's Avatar
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Well - i fixed the issue. The connector/wire (from the pad sensor to under the hood near the brake fluid reservoir) was either assembled wrong by the P.O. or not connected all the way. I took it apart, fed it through to the wheel well - reconnected everything and the light was on. So I reversed the two pole connector - put it together - light goes out. Reassemble - light still out. Hurray!
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  #6  
Old 05-24-2006, 08:07 PM
GVB GVB is offline
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Why did you paint the calipers? You guys crack me up some times, dont take that the wrong way though.
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  #7  
Old 05-25-2006, 03:38 AM
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Quote:
Originally Posted by skiier3_9
Well - i fixed the issue. The connector/wire (from the pad sensor to under the hood near the brake fluid reservoir) was either assembled wrong by the P.O. or not connected all the way. I took it apart, fed it through to the wheel well - reconnected everything and the light was on. So I reversed the two pole connector - put it together - light goes out. Reassemble - light still out. Hurray!
do you have any pics of the painted calipers?

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