Test Point 4 - Reference Mark Sensor
TEST POINT 4Reference Mark Sensor
Note: Reference mark sensor can only be tested with help of an oscilloscope.
Tune in oscilloscope as described in Test Point 3.
1. Disconnect lower plug (3) in engine compartment at left side on plug plate.
2. Connect oscilloscope on center and lower flat male plugs of engine end plug section with test leads.
3. Crank engine with starter.
Screen should display single sine oscillation.
Oscillation must begin with a positive flank and more than 2 volts must be displayed on the screen at a starter speed of at least 200 rpm (amount of amplitude depends on speed).
If sensor signal is weaker than 2 volts or no signal is displayed check connections sensor and distance.
Measure internal resistance of term. 25 against term. 26 on DME multiple pin plug or speed sensor plug section.
Specification: 0.6 to 1.6 kohms
Replace reference mark sensor, if necessary.