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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Lighting Systems) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, observe the scan tool Auto Hdlp. Disable Sw. parameter while cycling the headlamp switch between the Auto and Off positions. The parameter should cycle between Active and Inactive.
    • If the parameter does not cycle between the specified values, refer to Headlamp Switch Circuit Test.
  2. Observe the scan tool Headlamp Switch parameter while cycling the headlamp switch between the Auto and Head position. The parameter should cycle between Active and Inactive.
    • If the parameter does not cycle between the specified values, refer to Headlamp Switch Test.
  3. With the headlamps ON, observe the scan tool Flash to Pass Switch parameter while pulling and releasing the flash to pass switch. The parameter should cycle between Active and Inactive.
    • If the parameter does not cycle between the specified values, refer to Turn Signal/Multifunction Switch Test.
  4. With the headlamps ON, observe the scan tool High Beam Select Switch parameter while switching the headlamp dimmer switch between the low and high beam positions. The parameter should cycle between Active and Inactive.
    • If the parameter does not cycle between the specified values, refer to Turn Signal/Multifunction Switch Test.
  5. Ignition ON, with a test lamp connected to ground, probe each of the test points on either LO BEAM Fuse while commanding the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF at one or both of the fuse test points when changing between commanded states.
    • If the test lamp is always OFF, or remains always ON, refer to Low Beam PCB Relay Circuit Test.
    • If the test lamp turns ON and OFF, refer to Headlamps Circuit Test
  6. Ignition ON, with a test lamp connected to ground, probe each of the test points on either HI BEAM Fuse while commanding the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF at one or both of the fuse test points when changing between commanded states.
    • If the test lamp is always OFF, or remains always ON, refer to High Beam PCB Relay Circuit Test.
    • If the test lamp turns ON and OFF, refer to High Beam Circuit Test
  7. Ignition ON, headlamps ON, observe the high beam indicator on the IPC while cycling the high beam dimmer switch ON and OFF. The indicator should turn ON and OFF when changing between commanded states.
    • If the indicator is always OFF or remains always ON, replace the IPC.
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