P161C

P161C-OIL VISCOSITY SENSOR PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The output from the viscosity sensor to the Powertrain Control Module (PCM) is a pulse width modulated (PWM) signal that is translated by the PCM into a viscosity value. When the oil temperature is between -25°C (-13°F) and -35°C (-31°F) the PCM will use the signal from the viscosity sensor to determine the oil viscosity level. If the PCM determines that the oil viscosity is too low (oil is too thick), the glow plug light on the dash will flash and a text message will appear on the EVIC instructing the operator to wait to start the engine.

- When Monitored:
Ignition on, engine running and oil temperature is between -25°C (-13°F) and -35°C (-31°F).

- Set Condition:
The Powertrain Control Module (PCM) detects an implausible Oil Viscosity Signal.





1. ACTIVE DTC
1. Start the engine.
2. With the scan tool read DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. OIL VISCOSITY SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the Oil Viscosity Sensor harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance between Oil Viscosity Signal circuit and ground at the Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the Oil Viscosity Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. OIL VISCOSITY SIGNAL CIRCUIT SHORTED TO THE SENSOR GROUND CIRCUIT
1. Measure the resistance between the Oil Viscosity Signal circuit and the Sensor ground circuit at the Sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the short between the Sensor ground and the Oil Viscosity Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. EXCESSIVE RESISTANCE IN THE OIL VISCOSITY SENSOR SIGNAL CIRCUIT
1. Measure the resistance of the Oil Viscosity Signal circuit from the PCM C2 harness connector to the Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the excessive resistance in the Oil Viscosity Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. OIL VISCOSITY SIGNAL CIRCUIT SHORTED TO THE VOLTAGE
1. Turn the ignition on.
2. Measure the voltage on the Oil Viscosity Signal circuit at the Sensor harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the Oil Pressure Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. OIL VISCOSITY SENSOR
1. Turn the ignition off.
2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oil Viscosity Sensor and the Powertrain Control Module (PCM).
3. Look for any chafed, pierced, pinched or partially broken wires.
4. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Powertrain Control Module harness connectors.
5. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace the Oil Viscosity Sensor. Oil Viscosity Sensor - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.