Engine Speed Sensor: Testing and Inspection
Checking Engine Speed SensorNOTE:
For functional testing of engine speed sensor, "Read Measuring Value Block" function 08, display group 002.
- 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. 1 K(ohm)
If specified value is NOT obtained:
- Replace engine speed sensor.
If specified value is obtained:
- Connect multi meter 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 as follows:
- Connect VAG 1598 test box with VAG 1598/11 adapter harness to ECM wiring harness. (Adapter harness is not connected to ECM.) Connecting VAG 1598/31 Test Box
3-Pin Connector:
- Check shielding by checking for continuity between sensor connector terminal 3 and GND.
^ Specified value: maximum 1 (ohm)
- Check GND wire for continuity between sensor connector terminal 1 and test box socket 1.
^ Specified value: maximum 1 (ohm)
- Check signal wire for continuity between sensor connector terminal 2 and test box socket 2.
^ Specified value: maximum 1 ohm
ECM Harness Connectors:
If specified values are not obtained, eliminate short circuit or break in wiring between RPM sensor connector and ECM connector -C-.
Sensor connector ECM connector C terminal
1 5
3 2
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
- Crank 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.