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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls And Fuel - 2.5L (LCV) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P1176 or P1177 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
    2. NOTE:

    Additional DTCs will set when disconnecting the components.

  2. Disconnect the electrical connector at one of the following components, depending on the DTC that is set:
    • {P1176} B150 Fuel Tank Pressure Sensor
    • {P1177} B47 Fuel Pressure Sensor
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify the scan tool parameter:
    • {P1176} Fuel Pump Driver Control Module 5V Reference 1 = 5.01 V
    • {P1177} Fuel Pump Driver Control Module 5V Reference 2 = 5.01 V
    • If not the specified state after disconnecting a component from the circuit 

      Test or replace the component: The component that was disconnected last.

    • Go to next step: If the specified state after disconnecting a component from the circuit 
  5. Test for 4.8 to 5.2 V between the test points:
    • {P1176} 5 V Reference circuit terminal 3 @ Component harness & Ground
    • {P1177} 5 V Reference circuit terminal 1 @ Component harness & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Driver Control Module
    3. Test for infinite resistance between the test points:
      • {P1176} 5 V Reference circuit terminal 10 @ Control module harness & Ground
      • {P1177} 5 V Reference circuit terminal 12 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K111 Fuel Pump Driver Control Module
    • If greater than 5.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Driver Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:
      • {P1176} 5 V Reference circuit terminal 10 @ Control module harness & Ground
      • {P1177} 5 V Reference circuit terminal 12 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K111 Fuel Pump Driver Control Module
    • Go to next step: If between 4.8 and 5.2 V 
  6. All OK.
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