DTC Descriptor
DTC P0521: Engine Oil Pressure (EOP) Sensor Performance
DTC P0522: Engine Oil Pressure (EOP) Sensor Circuit Low Voltage.
DTC P0523: Engine Oil Pressure (EOP) Sensor Circuit High Voltage
Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Engine Oil Pressure 5-Volt Reference Circuit
| P0522
| P0522
| P0523
| P0521
|
Engine Oil Pressure Sensor Signal Circuit
| P0522
| P0522
| P0523
| P0521
|
Low Reference
| --
| P0523
| --
| P0521
|
Circuit/System Description
The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP sensor is a 3-wire sensor comprising of the signal circuit, the low reference circuit and the 5-volt reference circuit. The engine control module
(ECM) supplies 5 volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM monitors the signal circuit of the EOP sensor to determine the engine oil pressure sensor voltage is within
the normal operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor voltage is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM
senses a low signal voltage. The ECM sends the EOP information to the instrument panel cluster (IPC) via GMLAN serial data message.
Conditions for Running the DTC
DTC P0521 (5.3L Engine)
| • | The engine is running with engine speed between 700-3,500 RPM. |
| • | Oil temperature is less than 150°C (302°F). |
| • | Engine load stability is less than 250 kPa (36.2 psi). |
| • | Engine predicted pressure is between 50 kPa (7.3 psi) and 400 kPa (58 psi). |
| • | No crank sensor DTCs set. |
| • | No coolant sensor DTCs set. |
| • | No intake air temperature sensor DTCs set. |
| • | No oil pressure sensor circuit DTCs set. |
DTC P0521 (3.9L and 3.5L Engine)
| • | The engine is running with engine speed between 700-3,500 RPM. |
| • | Oil temperature is less than 140°C (284°F). |
Conditions for Setting the DTC
DTC P0521 (5.3L Engine)
The ECM detects that the difference between the predicted oil pressure and the actual oil pressure is either less than 47 kPa (6.8 psi) or greater than 50 kPa (7.3 psi).
DTC P0521 (3.9L and 3.5L Engine)
| • | The ECM does not detect a change in the engine oil pressure of at least 34.5 kPa (5.0 psi). |
| • | The above condition is present over a predetermined variance of engine speed. |
DTC P0522
| • | The ECM detects that the EOP sensor signal circuit is less than 0.2 volt. |
| • | The above condition is present for greater than 10 seconds. |
DTC P0523
| • | The ECM detects that the EOP sensor signal circuit is greater than 4.8 volts. |
| • | The above condition is present for greater than 10 seconds. |
Action Taken When the DTC Sets
| • | The ECM records the operating conditions at the time the diagnostics test fails. The ECM displays this information in the Failure Records on the scan tool. |
| • | The IPC illuminates the EOP indicator. |
Conditions for Clearing the DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
Reference Information
Schematic Reference
Instrument Cluster Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- Engine ON, observe the scan tool Engine Oil Pressure Sensor parameter. The reading should be between 0.2 and 4.8 volts or between 41 and 448 kPa (6 and 65 psi).
| ⇒ | If not within the specified range, refer to Circuit/System Testing. |
- Verify the scan tool Engine Oil Pressure Sensor parameter changes by more than 34.5 kPa (5 psi) while running the engine at various RPM's. The reading should vary by at least 34.5 kPa (5 psi).
| ⇒ | If the specified value does not vary, refer to: |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) sensor.
- Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
- Verify the scan tool Engine Oil Pressure Sensor parameter is less than 0.2 volts.
| ⇒ | If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM. |
- Install a 3-amp fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than 4.8 volts.
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
- If all circuits test normal, test or replace the EOP sensor.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
