Engine Speed Sensor: Testing and Inspection

- Disconnect Engine Speed (RPM) sensor harness connector.
^ Gray sensor and harness
- Switch multimeter Fluke 83 to resistance range.

3-Pin Connector:

- Connect multimeter to terminals 1 and 2 using jumper leads from VW 1594.
^ Must be approx. 1000 ohms.

If NO:
- Replace RPM sensor.

If YES:
- Connect multimeter between terminals 1 and 3 and then terminals 2 and 3.
^ Both must be infinite ohms (no continuity).

If NO:
- Replace RPM sensor.

If YES:
- Check wiring between sensor harness connector and Engine Control Module (ECM) harness connector as follows:
- Connect VAG 1598 Test Box to ECM harness connector using VAG 1598/5 adaptor cable. Refer to VAG 1598 Pin Out Box Connecting Connecting and Testing VAG 1598 Pin Out Box
^ ECM is not connected.

3-Pin Connector:

- Check the following terminals for continuity and/or short cir cuit using wiring diagrams:
^ Between sensor harness connector terminal 1 and test box socket 48.
^ Between sensor harness connector terminal 2 and test box socket 49.
^ Between sensor harness connector terminal 3 and test box socket 19 (GND).

Engine Control Module Harness Connector:

- Repair open circuit or short circuited wires between sensor harness connector and the ECM connector (terminals 48/49 and 19), if necessary.

If OK:
- Visually check teeth on starter ring gear.
- Remove bracket with RPM sensor and Crankshaft Position (CKP) sensor and inspect.
- Rotate engine slowly and examine ring gear for runout and broken and/or damaged teeth, replace if necessary.

If OK:
- Replace the ECM.