Test Point 13 - Engine Speed / Reference Mark Sensor

TEST POINT 13: - Engine speed/reference mark sensor

This test can only be performed with an oscilloscope. Connect up and adjust the workshop oscilloscope in accordance with the manufacturer's instructions.




Using test leads, connect the positive tester lead to control unit plug terminal 23, and the negative tester lead to control unit plug terminal 6.




Crank the engine with the starter motor. The screen must display sine waves of at least 3 V (engine speed impulses), and these must include a higher amplitude peak (reference mark).

If the voltage signal is too low (<3 V), dirt may have affected the distance between the sensor and the gear ring.

Engine speed sensor plug:

No display:
Disconnect the engine speed sensor plug connection at the plug strip in the engine compartment. Using test leads, connect the lead from the tester to the center and outer plug contact (terminals 1 and 2, pin side). Start the engine. The sine wave pattern must be displayed on the screen.

NOTE:
- If connection 3 is grounded, the image must not change.
- If it changes, check sensor for continuity, correct gap and freedom from dirt.