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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting >> Diagnostic Information and Procedures >> Daytime Running Lamps Malfunction >> Circuit/System Verification

Circuit/System Verification

  1. Ignition ON, observe the scan tool Ambient Light Sensor parameter voltage while carefully supplying sufficient light to simulate daylight conditions to the ambient light sensor, then covering to simulate darkness. The voltage reading should change from approximately 0.69 to 4.52 volts.
    • If the reading does not change between light and dark, refer to Circuit/System Testing  For Ambient Light Sensor Circuit Test.
  2. Connect a test lamp between the relay side of the DRL fuse and ground.
  3. Verify that the test lamp turns on and off while commanding the daytime running lamps ON and OFF with a scan tool.
    • If the test lamp does not turn on and off while changing between the commanded states, refer to Circuit/System Testing  For DRL Relay Control Circuit Test.
  4. If 1 or both of the daytime running lamps do not turn on and off, refer to Circuit/System Testing  For Daytime Running Lamps Circuit Test.
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