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Tahoe / Yukon Service Manual

Fuel Gauge Malfunction

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 Descriptors DTC P0461 Fuel Level Sensor Performance DTC P0462 Fuel Level Sensor Circuit Low Voltage DTC P0463 Fuel Level Sensor Circuit High Voltage DTC P0464 Fuel Level Sensor Circuit Intermittent Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Fuel Level Sensor Signal P0462 P0463 P0463 P0461, 1
Low Reference — P0463 P0463 P0461, 1
1. Fuel Gauge Malfunction

Circuit/System Description The fuel level sensor changes resistance based on fuel level and is wired to the K111 Fuel Pump Power Control Module. The K111 Fuel Pump Power Control Module sends the fuel level sensor reading to the Engine Control Module (ECM) via serial data. The ECM monitors the fuel level sensor signal in order to determine the fuel level. When the fuel tank is full, the resistance of the fuel level sensor is low. When the fuel tank is empty, the resistance of the fuel level sensor is high. The ECM uses the signal voltage of the fuel level sensor to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data to the body control module (BCM). The BCM then sends the fuel level percentage via serial data to the P16 Instrument Panel Cluster Control Module to control the fuel gauge. Conditions for Running the DTC The engine is running The system voltage is between 11–16 V Conditions for Setting the DTC P0461 The ECM detects a change in fuel level of less than a specified amount (typically 3–10 L or 0.8– 2.6 gal) over a specified driving distance (typically 240–320 km or 150–200 miles). P0462 The signal voltage is less than 0.25 V. The above conditions must be met for 5 seconds. P0463 The signal voltage is greater than 4.7 V. The above conditions must be met for 5 seconds. P0464 The fuel level change is greater than 10%. The above conditions must be met for 30 seconds. DTC P0464 runs and fails 2 out of 3 test cycles. Action Taken When the DTC Sets P0461, P0462, and P0463 P0461, P0462, and P0463 are Type B DTCs The fuel gauge defaults to empty The low fuel indicator illuminates P0464 P0464 is a Type A DTC Conditions for Clearing the DTC P0461, P0462, and P0463 are Type B DTCs P0464 is a Type A DTC Reference Information Schematic Reference Instrument Cluster Schematics Connector End View Reference Master Electrical Component List Description and Operation Instrument Cluster Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Ignition ON.
  2. Verify the DTC P0461, P0462, P0463, or P0464 are not set ⇒ If DTC P0461, P0462, P0463, or P0464 are set Refer to Circuit/System Testing ⇓ If DTC P0461, P0462, P0463, or P0464 are not set
  3. If equipped, verify the mechanical fuel level gauge sweeps during Ignition Instrument Panel Cluster initialization. ⇒ If the fuel level gauge does not sweep Replace the P16 Instrument Panel Cluster Control Module. ⇓ If the fuel level gauge sweeps
  4. Ignition ON, Verify the low fuel level indicator turns ON and OFF during Instrument Panel Cluster initialization bulb check. ⇒ If the low fuel level indicator does not turn ON and OFF Replace the P16 Instrument Panel Cluster Control Module ⇓ If the low fuel level indicator turns ON and OFF
  5. Verify the scan tool Fuel Level Sensor parameter is between 5–95% and varies with fuel level. ⇒ If not between 5–95% or does not vary with fuel level Refer to Circuit/System Testing ⇓ If between 5–95% and varies with fuel level
  6. All OK. Circuit/System Testing
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A7 Fuel Tank Fuel Pump Module. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the low reference circuit terminal 6 and ground. ⇒ If 10 Ω or greater 2.1. Ignition OFF, disconnect the harness connector at the K111 Fuel Pump Power Control Module. 2.2. Test for less than 2 Ω in the low reference circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K111 Fuel Pump Power Control Module. ⇓ If less than 10 Ω
  3. Ignition ON.
  4. Verify the scan tool Fuel Level Sensor parameter is less than 5%. ⇒ If greater than 5% 4.1. Ignition OFF, disconnect the harness connector at the K111 Fuel Pump Power Control Module. 4.2. Test for infinite resistance between the signal circuit terminal 5 and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the K111 Fuel Pump Power Control Module. ⇓ If less than 5%
  5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 6.
  6. Verify the scan tool Fuel Level Sensor parameter is greater than 95%. ⇒ If less than 95% 6.1. Ignition OFF, disconnect the harness connector at the K111 Fuel Pump Power 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. Ignition OFF 6.4. Test for less than 2 Ω in the signal circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K111 Fuel Pump Power Control Module. ⇓ If 95% or greater
  7. Test or replace the B46 Fuel Level Sensor.
  8. Operate the vehicle within the Conditions for Running the DTC.
  9. Verify the condition does not return. ⇒ If the condition returns Replace the K20 Engine Control Module. ⇓ If the condition does not return
  10. All OK. Component Testing
  11. Ignition OFF, remove the Fuel Level Sender.
  12. Sweep the Fuel Level Sensor through its full range of motion while measuring resistance between the signal terminal 5 and the low reference terminal 6.
  13. Test for a minimum resistance value of 37-43 Ω and a maximum value of 245-255 Ω without any spikes or dropouts. ⇒ If minimum resistance is not 37-43 Ω, maximum resistance is not 245-255 Ω, or if there are any spikes or dropouts Replace the Primary Fuel Level Sensor. ⇓ If minimum resistance is 37-43 Ω, maximum resistance is 245-255 Ω, and if there are no spikes or dropouts
  14. All OK. 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