Engine Speed (RPM) Sensor -G28-, Checking

Engine Speed (RPM) Sensor -G28, Checking


NOTE: The engine speed sender is a combined speed sender and reference mark sender Without a signal from the Engine Speed (RPM) sensor - G28 the engine cannot be started. If the signal from the Engine Speed (RPM) sensor -G28 fails while the engine is running, the engine will cut out immediately.


Checking Engine Speed (RPM) sensor
- Before carrying out test, make sure that sensor is correctly installed and firmly seated.
- Disconnect harness connector for Engine Speed (RPM) sensor (grey connector).







- Connect multimeter (Fluke 83 or equivalent) (resistance test range) to terminals 2 and 3 on connector for engine speed sensor using test lead from VAG1594 connector test kit
Specification: approx. 730 - 1000 ohm


NOTE:
- The resistance value for the engine speed sensor is based on a temperature of 20 °C
- The resistance increases as the temperature rises.


If the specification is not attained:
- Replace engine speed sensor.

If the specification is attained:
- Connect multimeter (Fluke 83 or equivalent) (resistance test range) between terminals 2 and 1 (Ground (GND)) and between terminals 3 and 1 (Ground (GND)).
Specification: R Ohms (infinite Ohms / open circuit) in each test

If the specification is not attained:
- Replace Engine Speed (RPM) sensor.

If the specification is attained:

- Check wiring between sensor connector and engine control module as follows:
- Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection







- Test continuity of screening (shielded wire) between contact 1 on engine speed sender connector and socket 108 on test box.
Specification: max. 1 Ohms.

- Test continuity of negative wire from contact 2 on sender connector to socket 90 on test box.
Specification: max. 1 Ohms

- Test continuity of signal wire from contact 3 on sender connector to socket 82 on test box.
Specification: max. 1 Ohms.

If the values are not as specified:
- Rectify short or open circuit in wiring between sender connector and control module connector.

Terminal on sensor Terminal on control module
connector connector
1 108
2 90
3 82

- If no open circuits or short circuits are identified, replace Engine Control Module (ECM).