Test Point 21 - Speed/Reference Sensor

Test Point 23 - Speed/Reference Sensor:

1. Disconnect DME control unit electrical connector under drivers seat.
2. Connect oscilloscope across harness terminals 47 and 48.
3. Crank engine and observe scope pattern.

Engine Speed Sensor Scope Pattern:

4. The scope pattern should be as shown and at least 3 volts peak to peak. If the pattern is correct but voltage low check sensor adjustment.Adjustments If pattern is incorrect or does not exist, continue.

Terminal Identification:

5. Recheck for pattern directly at sensor connector, terminals 1 and 2.
6. If pattern is now correct, repair wiring. If pattern still is not available or incorrect, replace sensor.