Camshaft Position (CMP) Sensor -G40- Checking

Camshaft Position (CMP) Sensor G40 , Checking

NOTE: Use only gold-plated terminals when servicing terminals in harness connector of Camshaft Position (CMP) Sensor G40.

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements







- The Motronic Engine Control Module (ECM) J220 fuses OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.

Procedure







- Remove the engine cover with air filter.







- Disconnect the Camshaft Position (CMP) Sensor G40 electrical harness connector - 1 -.
- Switch the ignition on.







- Using a Multimeter , Check the Camshaft Position (CMP) Sensor G40 electrical harness connector terminals 1 to 3 for voltage.
Specified value: about 5.0 V
- Switch the ignition off.

If the specification was not obtained:

Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a Multimeter , Check the Camshaft Position (CMP) Sensor G40 electrical harness connector to the Motronic Engine Control Module (ECM) electrical harness connector for an open circuit.

Camshaft Position (CMP) Sensor
G40 electrical harness
connector terminals Motronic Engine Control Module (ECM) electrical harness test box sockets
1 98
2 86
3 108

Specified value: 1.5 Ohms Max.

If the specified value was not obtained:
- Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
- Check the wiring connection for damage, corrosion, lose or broken terminals.
- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and voltage supply was OK:
- Replace the Camshaft Position (CMP) Sensor G40.

If no malfunction is found in the wiring and voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) J220.
- Install the engine cover with filter.

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

- End of diagnosis.




With Manufacturer's Scan Tool

Camshaft Position (CMP) Sensor -G40-, Checking







Special tools and workshop equipment required
- V.A.G 1526 A Multimeter
- V.A.G 1527 B Voltage tester
- V.A.G 1594 A Connector test kit
- V.A.G 1598/31 Test box

The Camshaft Position (CMP) sensor -G40- indicates the ignition position for cylinder 1.

If the Camshaft Position (CMP) sensor -G40- fails to function, the knock recognition control is switched off and the ignition timing is retarded slightly because the signals can no longer be assigned to the cylinders. Furthermore, the charge pressure of the turbocharger is lowered.

Even without a signal from the Camshaft Position (CMP) sensor -G40-, the engine will continue to run and can also be restarted.
- When a malfunction is detected, the ECM produces one spark for each cylinder on every crankshaft revolution.
- The fact that the ECM is out of phase by one engine revolution does not have any noticeable effect on the injection system. If this happens, the fuel is injected "upstream" (before the closed intake valve) instead of while the intake valve is open. This has only a minor influence on the quality of the air/fuel mixture.

Checking activation
- Push back rubber grommet of connector for Camshaft Position (CMP) sensor -G40- back but leave connector attached.







- Connect LED voltage tester V.A.G 1527 B between receptacle 2 (Camshaft Position (CMP) sensor -G40- signal) and receptacle 1 (B+).

NOTE: Receptacles are numbered accordingly on the back of the connector.

- Operate starter for a few seconds.
- LED must flash.

NOTE: LED voltage testers with a low current consumption continue to glow faintly between activation from the ECM (rather than extinguishing completely) and become much brighter when activated.

If LED does not flash:

Checking power supply







- Disconnect Camshaft Position (CMP) sensor -G40- connector (arrow).







- Connect multimeter as follows to measure voltage:

Connector Measure to
terminal
1 Engine ground (GND)

- Switch ignition on.
- Specified value: approx. 5 V

Checking signal wire







- Connect multimeter as follows to measure voltage:

Connector Measure to
terminal
2 Engine Ground (GND)

- Switch ignition on.
- Specified value: approx. battery voltage (B+)

Checking Ground (GND) wire







- Check for open circuit, short to positive, or short to ground in following wiring connections:

Connector terminal Measure to
3 Engine Ground (GND)

- Repair any open/short circuit as necessary.

If the specified values are all achieved and the LED voltage tester does not flash (measured between terminals 1 and 2 with starter connector attached),

- Install a new Camshaft Position (CMP) sensor -G40-..

If specified values are not obtained:

Checking wiring between Camshaft Position (CMP) sensor -G40- and ECM
- Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect directly to ECM.







- Check for open circuit, short to positive, or short to ground in following wiring connections:

Connector Test box V.A.G 1598/31
terminal Socket
1 (B+) 98
2 (signal) 86
3 (ground) 108

- Repair any open/short circuit as necessary.

If a trial erasure of the DTC memory is followed by the replaced indication of a malfunction relating to the Camshaft Position (CMP) sensor -G40- although all previous tests were OK, the following malfunctions are possible:
- Rotor ring for Camshaft Position (CMP) sensor -G40- misaligned
- Unbolt Camshaft Position (CMP) sensor -G40- and ensure that rotor ring is correctly aligned on camshaft (if it is incorrectly installed, catch will be pressed flat when securing screw is tightened).
- If position of rotor ring is OK, check position of camshaft in relation to crankshaft.