Camshaft Position Sensor: Testing and Inspection
Camshaft Position Sensors, Checking
This procedure is used to check Camshaft Position (CMP) Sensors (G40, G300, G163, G301).
• Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the Camshaft Position (CMP) Sensor (G40).
Special tools, testers and auxiliary items required
• Multimeter.
• Diode test lamp.
• Wiring diagram.
Test requirements
• The Engine Control Module (ECM) (J623) fuses OK.
• Engine Control Module (ECM) Power Supply Relay (J363) OK.
• Battery voltage at least 12.5 V.
• 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.
Test procedure
- Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.
- Remove the front engine cover - arrows -.
- Remove the rear engine cover - arrows -.
Checking activation
- Using the Diode test lamp , check for voltage between terminal 2 (CMP sensor signal) and terminal 1 (B+) with the electrical harness connector connected to the Camshaft Position (CMP) Sensor.
- Operate the starter for a few Sec.
The LED must blink.
• Voltage testers do not go out completely during low current pick-up between activations by the ECM, but rather continue to glow a little and then get significantly brighter during activation.
- Switch ignition off.
If the LED blinks:
Replace the relevant Camshaft Position (CMP) Sensor
If the LED does not blink:
Checking voltage supply
- Disconnect the relevant Camshaft Position (CMP) Sensor electrical harness connector.
- Switch the ignition on.
- Using a Multimeter, check the Camshaft Position (CMP) Sensor electrical harness connector terminal 1 to engine ground for voltage.
Specified value: about 5 V.
- Switch the ignition off.
Checking signal wire
- Using a Multimeter, Check the Camshaft Position (CMP) Sensor electrical harness connector terminal 2 to engine ground for voltage.
- Switch the ignition on.
Specified value: Battery voltage.
- Switch the ignition off.
Checking Ground (GND)
- Using a Multimeter, Check the Camshaft Position (CMP) Sensor electrical harness connector terminal 3 to engine ground for voltage.
Specified value: about 10 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 (VAG1598/42).
If the manufacturers test box is not being used, perform the following step.
- Remove the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a Multimeter, Check the Camshaft Position (CMP) Sensor electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector for resistance.
• Camshaft Position (CMP) Sensor (G40) (bank 1).
• Camshaft Position (CMP) Sensor 2 (G163) (bank 2).
• Camshaft Position (CMP) Sensor 3 (G300) (bank 1).
• Camshaft Position (CMP) Sensor 4 (G301) (bank 2).
If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunction can be found:
- Replace the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing
Assembly is performed in the reverse order of removal.
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.