marlinspike

So my 8 inches of ground clearance got me to work, but about a minute after driving through one flooded portion of road my brake pad sensor light came on. Now, the pads were replaced about 300 miles ago, so there's no way they're worn. Looking in the wheels the pad sensors are still hooked up. Is there anything this could possibly require other than a new set of pad sensors?

Oh, and the pad sensor light on this car is only for the pad sensors, i.e. it doesn't do double duty (like the parking brake light does for instance).

shawn22

No.

Water will not mess up your brake pads.



I only helped you because you referenced star wars. Count yourself lucky.

marlinspike

I know it won't mess up my pads. My question is is there anything else in the sensor circuit that can be messed up, or is it just the sensors that I replace at every pad change?

Enforcer

try unhooking the pad sensors, blow them out with a air source, or unplug them on a dry day and let them sit for a while and dry out. the connections getting wet may have caused an issue with the resistance values of the sensor. they operate of a resistance value when the pad cuts into the sensor it opens the circuit and turns the light on so the water might have messed with the resistance. i was a certified mercedes technician for 5 years at a dealership and we dealt with pad sensors all the time

shawn22

Probably just a sensor, although anything that got wet electrically could possibly have been damaged.

I<3Strippers!

What kind of shitty German car are you driving? Have you googled this problem? Are you ready for fabrik8 to come in and pwn you with his resourceful knowledge?

marlinspike

Thanks. I'll just order new sensors because they're extremely cheap and I have an order coming my way from the Classic Center soon anyways. I know I've asked before, but I forget, are you in the 757?

Get off me. The water was above the bottom of the brake calipers (i.e. the lower sensors were completely submerged).

Fabrik8

If they're a resistance-type sensor as posted above, nothing should have been damaged except the sensor.

Usually the circuit is a resistor to a power supply (creating a current source) and the resistance of the sensor, and the voltage is measured between those two resistances (it's just a regular voltage divider circuit). Then the change of sensor resistance changes the ratio between the two resistors. Anyway, the nice part is that the upper resistor (to the power supply) limits the current so if the sensor is shorted then nothing bad happens.

So assuming it's a two wire sensor, you should have damaged exactly nothing.

marlinspike

It has one wire, like this

Fabrik8

Yep, should be same thing. The second wire of a two-wire resistive sensor is usually ground, so they're just using the chassis ground instead of using a second wire. Two wire sensors are usually used when the sensor circuit is powered from a sensor power supply from something like an ECU or body controller. The sensor ground and chassis ground are kept separate for noise reasons and because of possible corrosion issues (where the sensor would electrically attach to the chassis), so one-wire sensors aren't usually used. None of that applies in your case.