Supports the original Mercedes-Benz 3-pin oil pan sensor from example OM648 engines.
The sensor provides:
•Engine Oil Temperature.
•Engine Oil Level.
•Oil Quality (not currently decoded as it is generally not useful for performance or motorsport applications).
The sensor is powered from 5V and transmits all measurements as a PWM signal consisting of three consecutive pulses followed by a short pause. Each pulse represents one parameter:
Pulse 1 Oil Temperature 20-80% = -40 to +160°C
Pulse 2 Oil Level 20-80% = 0-80 mm
Pulse 3 Oil Quality Not used
Note: A duty cycle below approximately 20% or above 80% indicates an out-of-range or fault condition.
Sensor part number example: A0041535928
Wiring
Supply: +5V
Signal: PWM output
Ground: Sensor ground
Input configuration
Input configuration example on a MaxxECU RACE: Pull-up: Disabled. Input polarity: Rising edge / Active High.
Important: Do not enable the ECU's internal pull-up resistor. The Mercedes sensor contains its own output stage and is designed to operate without an external pull-up.
Implementation
•The decoder automatically synchronizes to the three-pulse PWM frame.
•The first two rising edges are used to measure the PWM cycle time.
•The high time of each pulse is converted into duty cycle.
•Pulse 1 is converted to Oil Temperature.
•Pulse 2 is converted to Oil Level.
•Pulse 3 (Oil Quality) is currently ignored.
•If no valid pulse is detected for more than 500 ms, synchronization is automatically reset and the next frame is used to re-synchronize.
