Camshaft Position Sensor, Checking
Special tools and workshop equipment required
- Multimeter
- wiring diagrams
Use only gold-plated terminals when servicing terminals in harness connector of Camshaft Position (CMP) Sensor -G40-.
Test requirements
- Fuses for Engine Control Module (ECM) -J623- OK refer to appropriate SYSTEM WIRING DIAGRAMS.
- 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.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .
Start diagnosis
-- Pull engine cover out of first mount at front arrow 1, then at right rear arrow 2 and finally at left rear arrow 3.
The use of nails, paper clips, or another unauthorized materials to back-probe electrical harness connectors is strictly prohibited and may cause damage to the electrical harness connectors, terminal ends or damage to a component. Use only the manufacturers test lead kit or an equivalent aftermarket test lead kit for back-probing all electrical harness connectors.
-- Using the low current voltage tester, check for voltage between terminal 1 and terminal 2 with the electrical harness connector connected to Camshaft Position (CMP) Sensor -G40-.
-- Operate the starter briefly.
The LED must blink.
Voltage testers do not go out completely during low current pickup 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 does not blink:
Checking voltage supply
-- Using a Multimeter, check the following wiring connection for voltage.
| Camshaft Position Sensor -G40- electrical harness connector terminal | Motronic Engine Control Module (ECM) -J623- electrical connector T121 terminal or test box socket |
|---|---|
| 1 | to GND |
-- Switch the ignition on.
Specified value: about 5 V.
-- Switch the ignition off.
Checking signal wire
If the manufacturers test box is being used. Perform the following step.
-- Install the Adapter Cable (121 Pin) VAG 1598/31.
-- Check sensor G40 integrity
-- Using multimeter, check the resistance at:
| Camshaft Position (CMP) Sensor -G40- connector terminals: | Value: |
|---|---|
| 1 to 3 | approx. 3 mΩ |
| 1 to 2 | approx. 1 mΩ |
| 2 to 3 | approx. 6 mΩ |
-- If readings not in range, replace G40
-- If readings within range, continue with diagnosis.
-- Using a Multimeter, check the following wiring connection for voltage.
| Camshaft Position (CMP) Sensor -G40- | Motronic Engine Control Module (ECM) -J623- electrical connector T121 terminal or test box socket |
|---|---|
| 2 | GND |
-- Reconnect G40 connector
-- Switch the ignition on.
Specified value: approx. 5 V.
-- Switch the ignition off.
Checking Ground (GND)
-- Using a Multimeter, check the following wiring connection for voltage.
| Camshaft Position Sensor -G40- electrical harness connector terminal | Motronic Engine Control Module (ECM) -J623- electrical connector T121 terminal or test box socket |
|---|---|
| 3 | Battery positive (+) |
Specified value: about 10 V.
If the specified values are obtained:
-- Replace Camshaft Position (CMP) Sensor -G40-. Refer to CAMSHAFT .
If the specified values are not obtained:
Checking resistance
-- Using a Multimeter, check the following wiring connections for an open circuit.
- Camshaft Position (CMP) Sensor -G40-
| Camshaft Position Sensor -G40- electrical harness connector terminal | Motronic Engine Control Module (ECM) -J623- electrical connector T121 terminal or test box socket |
|---|---|
| Pin 3 Battery Positive (+) | 108 |
| Pin 2 Signal | 86 |
| Pin 1 Ground (GND) | 98 |
Specified resistance 1.5 Ω max.
-- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
-- If necessary, repair the wiring connection.
-- Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
-- Perform a road test to verify repair.
If the DTC does not return:
Repair complete, Generate readiness code. Refer to READINESS CODE .
-- End diagnosis.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to MOTRONIC ENGINE CONTROL MODULE, REPLACING .
-- Assembly is performed in the reverse of the removal.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE, SETTING .
End of Diagnosis.