My wife's brake pad warning light came on the other day. Should it say which pads need changing? I looked and they both seem to have a bit of pad remaining.

08 ML350

 

It has always been a visual inspection on all four wheels.

 

Thank you.

 

Another question. Aren't the sensors only on one side of the vehicle...on the inside pad (the pad you can't see from just looking at the wheel)?

 

Yes, passenger side on USA vehicles, drivers side on mine!

It's a simple sensor that just shorts to ground. To test, get a low wattage test lamp connected to battery + and probe the sensor fly lead at the hub connector. Be careful separating them as they can be stuck! If the bulb lights then the sensor is shorted to ground.

I've seen this when "mechanics" have fitted the sensor to the brake pad incorrectly, or it may just be faulty.

Oh, you'll have to remove the wheel for access.

 

thanks!

 

Not sure if it helps but the sensor works on becoming open circuit when it gets worn - small conductor close to disk face that wears off when hits disk - normally enshrouded in plastic - at least that is how it works on my Australian car (not to earth-there are 2 wires).

You may have a loose plug/damaged cable etc

I changed pads recently and had the wear sensor on - as a temporary measure I just stripped back the wires close to the body conector plug - and soldered and insulated - the problem went away. Obviously the wear sensor is now inoperative but I will change it next time I have the wheel off (I have ordered some in the meantime)

 

Once the sensor is triggered, how much more pad is left? Meaning can I drive for another week before getting new pads due to my mechanic not having any open slots at the moment?
Also how do you know if it's the rear or front pads that need replacing?