Buick Regal: Engine Oil Level Sensor Diagnosis
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptor
DTC P250A
Engine Oil Level Switch Circuit
Diagnostic Fault Information
1. DIC message Engine Oil Level Low always ON
2. DIC message Engine Oil Level Low always OFF
Typical Scan Tool Data
Engine Oil Level Switch
Circuit/System Description
The engine oil level sensor/switch is normally-closed with proper engine oil
level. The switch opens
when the engine oil level drops below a calibrated level. The engine control
module (ECM) monitors the
engine oil level signal circuit when the ignition is ON, and the engine is OFF.
With the switch in the closed position, the ECM detects a low voltage on the
signal circuit. With the switch in the open
position, the ECM detects a high voltage on the signal circuit. When high
voltage is detected on the
signal circuit, the ECM will send a serial data message to the instrument panel
cluster (IPC). The IPC
will then display a message on the driver information center (DIC) or illuminate
a low engine oil level
lamp.
The following information determines the message sent from the ECM to the IPC:
- The Low Engine Oil Level message lamp is displayed only after the ECM
detects a high voltage
on the signal circuit for three consecutive ignition cycles, followed by an
ignition OFF event from
15 minutes to greater than 50 minutes, depending on engine oil temperatures.
- The Low Engine Oil Level message is turned OFF when the ECM detects a
low voltage on the
signal circuit after an ignition OFF event for greater than 90 seconds,
followed by an ignition ON
event for less than 1 second.
Conditions for Running the DTC
Ignition ON.
Conditions for Setting the DTC
The ECM detects a high voltage on the signal circuit for three consecutive
ignition cycles, followed by
an ignition OFF event from 15 minutes to greater than 50 minutes, depending on
engine oil
temperatures.
Action Taken When the DTC Sets
Engine Oil Level Low message activated.
Conditions for Clearing the DTC
The ECM detects a low voltage on the signal circuit after an ignition OFF
event for greater than 90
seconds, followed by an ignition ON event for less than 1 second.
Reference Information
Schematic Reference
- Instrument Cluster Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Description and Operation
- Instrument Cluster Description and Operation
- Indicator/Warning Message Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify proper engine oil level.
Add oil as necessary.
- Go to next step: If at proper level
2. Ignition ON, verify the scan tool Engine Oil Level parameter reads OK.
Refer to Circuit/System Testing.
3. All OK.
Circuit/System Testing
NOTE: Verify proper engine oil level before continuing with diagnosis.
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the B35 Engine Oil
Level Switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 Ω between the ground circuit terminal 1 and ground.
- Ignition OFF, disconnect the harness connector at the K20 Engine Control
Module.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 5 Ω
3. Ignition ON.
4. Verify the scan tool Engine Oil Level Switch parameter reads Low.
- If the Engine Oil Level Switch parameter reads OK
- Ignition OFF, disconnect the harness connector at the K20 Engine Control
Module.
- Test for infinite resistance between the signal circuit terminal 2 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K20 Engine Control Module.
- Go to next step: If the Engine Oil Level Switch parameter reads Low
NOTE: If a short to voltage is found on the signal circuit, the fuse in
the 3A
jumper wire will open.
5. Install a 3A fused jumper wire between the signal circuit terminal 2 and
the ground circuit
terminal 1.
6. Verify the scan tool Engine Oil Level Switch parameter reads OK.
- If the Engine Oil Level Switch parameter reads Low
- Ignition OFF, disconnect the harness connector at the K20 Engine Control
Module, ignition
ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open/high resistance on the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If the Engine Oil Level Switch parameter reads OK
7. Test or replace the B35 Engine Oil Level Switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Displays and Gauges Component Replacement Reference
- Control Module References for control module replacement, programming,
and setup
READ NEXT:
Diagnostic Instructions
Perform the Diagnostic System Check prior to using this diagnostic
procedure: Diagnostic
System Check - Vehicle
Review the description of Strategy Based Diagnosis:Strateg
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Ambient Air Temperature Calculation Reset (with Ambient Air
Temperature Sensor Wired to ECM)
Diagnostic Instructions
Perform the Diagnostic System Check prior to using this diagnostic
procedure: D
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