With Generic Scan Tool

Engine Speed (RPM) sensor, checking

Function

The engine speed (RPM) sensor -G28- detects engine speed and reference marks. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.

Recommended special tools and equipment
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test sequence






- Disconnect gray 3-pin harness connector to engine speed (RPM) sensor (arrow).

- Measure resistance of sensor between terminals 1 & 2 of connector -1-.

Specified value: 400 to 1000 Ohms

- Check sensor for shorts between terminals 1 & 3 and 2 & 3.

Specified value: Infinity Ohms

If specified values are not obtained:

- Replace Engine Speed (RPM) Sensor -G28-.

- Erase DTC memory of Engine Control Module (ECM).

- Generate readiness code.

If no DTC is found on sensor:

- Connect test box to control module wiring harness.






- Check wires between test box and 3-pin connector for open circuits according to wiring diagram.

Terminal 1 & socket 56
Terminal 2 & socket 63
Terminal 3 & socket 2

Wire resistance: max: 1.5 Ohms

- Also check wires for short circuits to each other, to vehicle Ground (GND) and to B+.

Specified value: Infinity Ohms

If no wiring faults are found:

- Remove sensor and check sensor wheel for secure fit, damage, and run-out.

Note: There is a larger-sized gap on the sensor wheel. This gap is the reference mark and does not mean that the sensor wheel is damaged.

If no faults are found in the sensor wheel:

- Replace Motronic Engine Control Module (ECM) -J220-.