Engine Speed Sensor: Testing and Inspection

CHECKING ENGINE SPEED SENSOR

PROCEDURE
- Check that sensor is installed correctly.
- Disconnect gray harness connector.

3-Pin Connector:

- Connect multimeter (Fluke 83 or equivalent) to terminals 1 and 2 of connector in connector station, using adapter cable VW 1594 connector test kit.
^ Specified value: approx. 1K ohms

If specified value is NOT obtained:
- Replace engine speed sensor.

If specified value is obtained:
- Connect multimeter (Fluke 83 or equivalent) to terminals 1 and 3 (Ground) and to terminals 2 and 3 (Ground).
^ Specified value: Infinite ohms in each case (no continuity).

If specified values are not obtained:
- Replace engine speed sensor.

If specified value is obtained:
- Check wiring between sensor connector and ECM.

Wiring Checks
- Connect VAG 1598/19 test box to ECM wiring harness.

3-Pin Connector:

- Check for continuity between sensor connector terminal 3 and GND.
^ Specified value: maximum 1.0 ohm
- Check GND wire for continuity between sensor connector terminal 1 and test box socket A 11.
^ Specified value: maximum 1.0 ohm
- Check signal wire for continuity between sensor connector terminal 2 and test box socket A 9.
^ Specified value: maximum 1.0 ohm

ECM Connectors:

If specified values are not obtained:
- Repiar short circuit or break in wiring between RPM sensor connector and ECM connector.

Sensor connector ECM connector terminal
1 A 11
3 A 9
Ground 4(GND)

If no malfunction has been found up to this point:
- Inspect teeth on starter gear.
^ The starter must be removed in order to check the gear
- Turn engine slowly and check flywheel for runout and also whether any teeth are broken or damaged; replace if necessary.

If no malfunction was found in all tests so far:
- Replace ECM.