Fuel Gauge Sender, Checking

Sender for fuel gauge, checking

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
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements





- The respective fuses of Diesel-Direct fuel injection system must be OK:
- Battery voltage must be at least 11.5 Volts.

Test sequence
- Switch ignition off.
- Disconnect harness connector for engine speed sensor.

Vehicles with 80-pin control module




- Measure resistance between terminals 2 + 3.
Specified value: 1.0 to 1.5 k ohms

Vehicles with 121-pin / 154-pin control module




- Measure resistance between terminals 1 + 2 at connector to sensor.
Vehicles with engine code ALH
Specified value: 1.1 to 1.6 k ohms

Vehicles with engine code BEW
Specified value: 450 to 550 ohms

Continuation for all vehicles

If specified value is not obtained:
- Replace Engine Speed (RPM) Sensor -G28-.
- Erase DTC memory of control module for Diesel-Direct fuel injection system, Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If specified value is obtained:
- Connect test box to control module wiring harness, connect test box for wiring test. Test Box, Connecting For Wiring Test

Vehicles with 80-pin control module




- Check wires between test box and 3-pin connector for open circuit according to wiring diagram.
Terminal 1 + socket 69
Terminal 2 + socket 67
Terminal 3 + socket 71
Wire resistance: max. 1.5 Ohm

Vehicles with 121-pin control module




- Check wires between test box and 3-pin connector for open circuit according to wiring diagram.
Terminal 1 + socket 102
Terminal 2 + socket 110
Terminal 3 + socket 86
Wire resistance: max. 1.5 Ohm

Vehicles with 154-pin control module
- Connect adapter cable (V.A.G. 1589/39-1) to test box (V.A.G. 1589/42).





- Check wires between test box and 3-pin connector for open circuit according to wiring diagram.
Terminal 1 + socket 58
Terminal 2 + socket 43
Terminal 3 + socket 43
Wire resistance: max. 1.5 Ohm

Continuation for all vehicles
- Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite Ohm

If no malfunctions are detected in wires:
- Remove sensor and check sensor wheel for secure fit, damage, and run-out.

If no malfunction can be detected:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes