Many master cylinder，especially systems that are a diagonal split，usually use a brake fluid level sensor or Switch in the master cylinder reservoir.
this sensor will light the red brake warning lamp on the dash if low brake fluid level is detected. A float-type sensor or a magnetic reed switch are commonly used and provide a complete electrical circuit when the brake fluid level is low
After refilling the master cylinder reservoir to the correct level, the red "brake" warning lamp should go out
①Components of the reservoir
1. Reservoir
2. Float
3.REED SWITCH
4. CAP
5. MAGNET
②Brake fluid level sensor type:
1. on the reservoir body 2.on the reservoir cap
Recently received sample test feedback from a professional customer
Q: Why is the resistance of the sensor float of our sample oil pot at low position at 0.2 0hms, while that of OE parts is at 2.9 0hms？
The following test data provided by him：
A:The sensor on the cylinder's reservoir is just a switch that senses the tongue opening and closing function via a magnetic oil float. Through customer response data analysis, it does not affect the use of function.
What is oil float ?
It is magnetic and acts as a cue if the brake fluid gets too low, the float reaches the bottom of its travel and closes a set of switch contacts allowing the ABS or brake warning light to come on.
Our inspection video:
Connect the detection interface with the oil pot sensor interface. When the oil pot float is at its lowest, the indicator light is on; otherwise, When the oil pot float is at its highest the indicator light is off