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Home >> Chevrolet >> 2021 >> Tahoe SSV >> Repair and Diagnosis >> Body & Frame >> Windows >> Fixed And MOVEABLE Window System >> Diagnostic Information and Procedures >> DTC B1954 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: M74LR Rear Side Door Window Regulator Motor-Left
  3. Connect a test lamp between the test points: Signal circuit terminal 3 & B+
  4. Ignition - On / Vehicle - In Service Mode
  5. Operate the component: S79LR Rear Side Door Window Switch-Left - Pulled

    Verify the test lamp state:

    S79LR Rear Side Door Window Switch-Left - Not Used = Test lamp Off

    S79LR Rear Side Door Window Switch-Left - Pulled = Test lamp On

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left
    2. Test for infinite resistance between the signal 1185 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the signal 1185 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the S79LR Rear Side Door Window Switch-Left
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left ignition ON.
    2. Test for less than 1 V between the signal 1185 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the S79LR Rear Side Door Window Switch-Left
    • Go to next step: If the test lamp turns ON and OFF 
  6. Connect a test lamp between the test points: Signal circuit terminal 7 & B+
  7. Ignition - On / Vehicle - In Service Mode
  8. Operate the component: S79LR Rear Side Door Window Switch-Left - Pressed

    Verify the test lamp state:

    S79LR Rear Side Door Window Switch-Left - Not Used = Test lamp Off

    S79LR Rear Side Door Window Switch-Left - Pressed = Test lamp On

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left
    2. Test for infinite resistance between the signal 1187 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the signal 1187 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the S79LR Rear Side Door Window Switch-Left
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left, ignition ON.
    2. Test for less than 1 V between the signal 1187 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the S79LR Rear Side Door Window Switch-Left.
    • Go to next step: If the test lamp turns ON and OFF 
  9. Connect a test lamp between the test points: Signal circuit terminal 5 & B+
  10. Ignition - On / Vehicle - In Service Mode
  11. Operate the component: S79LR Rear Side Door Window Switch-Left - Pressed & Pulled

    Verify the test lamp state:

    S79LR Rear Side Door Window Switch-Left - Not Used = Test lamp Off

    S79LR Rear Side Door Window Switch-Left - Pressed = Test lamp On

    S79LR Rear Side Door Window Switch-Left - Pulled = Test lamp On

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left
    2. Test for infinite resistance between the signal 5048 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the signal 5048 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the S79LR Rear Side Door Window Switch-Left
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch-Left, ignition ON.
    2. Test for less than 1 V between the signal 5048 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the S79LR Rear Side Door Window Switch-Left.
    • Go to next step: If the test lamp turns ON and OFF 
  12. Test or replace the component: M74LR Rear Side Door Window Regulator Motor-Left
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