Functional description
The sensor wheel (= multi-pole sensor wheel) has 58 magnetic pole pairs as well as a reference point. The reference point of the multi-pole sensor gear is shown by a pole pair that is twice as long.
The reference point enables detection of the top dead center of the 1st cylinder. By monitoring the individual pairs of poles, the hall effect sensor delivers a certain number of signal jumps to the engine control.
The active crankshaft sensor detects the direction of rotation of the crankshaft as well as the air gap in relation to the sensor wheel.
| Item | Explanation |
|---|---|
| 1 | Crankshaft sensor |
| 2 | Multi-pole sensor gear |
| 3 | three-pin plug connection |
The engine control unit uses the scanned signals to calculate the duration as well as the length of a crankshaft revolution. The time the sensor wheel requires to rotate past the Hall effect sensor is referred to as the crankshaft revolution per time.
For starting the engine, the engine control unit checks the following preconditions:
- error-free signal from the crankshaft sensor and camshaft sensor
- both signals must be detected in a specific chronological sequence
This process is referred to as synchronization and is only performed when the engine is started. It is only the synchronization process that enables the engine control unit to activate fuel injection correctly.
If the crankshaft sensor signals fails (with the 1st crankshaft revolution) or an invalid synchronization is detected for the engine start, the diagnosis starts immediately. The camshaft sensor signals are read here. If 12 flanks on the camshaft are read and the fault is still there, a fault is stored.
As soon as no crankshaft sensor signals are received or there is no valid synchronization with the engine running, debouncing starts.