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Tahoe / Yukon Service Manual

DTC P250A

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 Engine Oil Level Switch Circuit Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage
Engine Oil Level Sensor Signal 2 P250A, 1 —
Engine Oil Level Sensor Ground — P250A, 1 —
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 Short to Ground Open Short to Voltage
Operating Conditions: Ignition ON Parameter Normal Range: OK
Engine Oil Level Sensor/Switch Signal OK Low OK
Engine Oil Level Sensor/Switch Ground — Low —

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 P16 Instrument Panel Cluster Control Module. The P16 Instrument Panel Cluster Control Module will then display a message or illuminate a low engine oil level lamp. The following information determines the message sent from the ECM to the P16 Instrument Panel Cluster Control Module: 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 Schematics Connector End View Reference Master Electrical Component List 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. ⇒ If not at proper level Add oil as necessary. ⇓ If at proper level
  2. Ignition ON, verify the scan tool Engine Oil Level parameter reads OK. ⇒ If not OK Refer to Circuit/System Testing. ⇓ If OK
  3. All OK. Circuit/System Testing
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B35 Engine Oil Level Indicator 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 (or A) and ground. ⇒ If 5 Ω or greater 2.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. 2.2. 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. ⇓ 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 4.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. 4.2. Test for infinite resistance between the signal circuit terminal 2 (or B) and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the K20 Engine Control Module. ⇓ If the Engine Oil Level Switch parameter reads Low
  1. Install a 3A fused jumper wire between the signal circuit terminal 2 (or B) and the ground circuit terminal 1 (or A).
  2. Verify the scan tool Engine Oil Level Switch parameter reads OK. ⇒ If the Engine Oil Level Switch parameter reads Low 6.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. 6.2. 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 6.3. 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. ⇓ If the Engine Oil Level Switch parameter reads OK
  3. Replace the B35 Engine Oil Level Indicator 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