Engine Speed (RPM) Sensor -G28-, Testing

Engine speed (RPM) sensor -G28-, checking

NOTE:
- The signal is generated by the engine speed (RPM) sensor -G28- processed in the Engine Control Module (ECM) and directed to various parts of the electronic system (e.g. control module for A/C or ABS / EDS) from terminal 37 of the ECM. Engine speed signal and wire connections are monitored by theses systems.
- Checking engine speed signal:
- Checking engine speed sensor -G28.

Special tools and equipment






- VAG1526A
- VAG1594A
- VAG1598/31


NOTE: The engine speed (RPM) sensor detects RPM and reference marks. The engine cannot be started without a signal from the engine speed (RPM) sensor -G28-. If the engine speed (RPM) sensor -G28- signal fails while the engine is running, the engine will stop immediately.

Test sequence
- Before performing test, check sensor for proper installation and proper fitting.
- Disconnect harness connector for the engine speed (RPM) sensor (identification: gray harness connector).






- Connect multimeter between terminal 2 and 3 for resistance measurement.

- Specification: 730 to 1000 ohms

NOTE: Resistance value of the engine speed (RPM) sensor is based on a temperature of 20 degree C. Resistance increases as temperature increases.

If specified value is not obtained:
- Replace engine speed (RPM) sensor.

If specified value is obtained:






- Connect multimeter to terminals 2 and 1 (shielding) and to terminals 3 and 1 (shielding) for resistance measurement.
- Specification: each infinity ohms (no continuity)

If specified value is not obtained:
- Replace engine speed (RPM) sensor.

If specified value is obtained:
- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Wiring and Component Testing Using VAG1598/31 Test Box






- Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

Harness connector VAG1598/31 test box
Terminal Socket
1 (shielding) 108
2 (Ground -GND-) 90
3 (signal) 82

- Repair open circuit or short circuit if necessary.

If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).