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Home >> Chevrolet >> 2010 >> Impala LTZ >> Repair and Diagnosis >> External Pages >> Different car >> Section 822 (Lighting Systems) >> Diagnostic Information and Procedures >> Interior Backlighting Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

Dimmer Switch Circuit Test

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 volts.
    • If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
  4. Ignition ON, test for B+ between the voltage reference circuit terminal 15 and ground.
    • If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool Dimming Control Signal parameter is greater than 2.6 volts.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the headlamp switch.

Interior Backlighting Circuit Test

  1. Ignition OFF, disconnect the harness connector at the component with the inoperative backlighting.
  2. Test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground.
    • Headlamp Switch terminal 8
    • Instrument Panel Cluster (IPC) terminal 6
    • Driver Window Switch terminal F
    • Driver Door Lock Switch terminal F
    • Outside Rearview Mirror Switch terminal B
    • Passenger Window Switch terminal C
    • Passenger Door Lock Switch terminal F
    • Radio terminal 8 X1
    • HVAC Control Module terminal 10 X1
    • Driver Information Display Switch terminal 5
    • Left Steering Wheel Controls terminal 8
    • Right Steering Wheel Controls terminal 1
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the appropriate supply voltage circuit terminal listed below and ground.
    • Headlamp Switch terminal 7
    • Instrument Panel Cluster (IPC) terminal 8
    • Driver Window Switch terminal B
    • Driver Door Lock Switch terminal G
    • Outside Rearview Mirror Switch terminal E
    • Passenger Window Switch terminal B
    • Passenger Door Lock Switch terminal G
    • Radio terminal 7 X1
    • HVAC Control Module terminal 1 X1
    • Driver Information Display Switch terminal 4
    • Left Steering Wheel Controls terminal 6
    • Right Steering Wheel Controls terminal 2
  4. Ignition ON, command the appropriate Incandescent Dimming or LED Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM
    • If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the component with the inoperative backlighting.
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