LEMON Manuals: Even more car manuals for everyone
Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Lighting Systems) >> Diagnostic Information and Procedures >> Front Fog Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

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.

Fog Lamp Switch Circuit Test

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. 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 Front Fog Lamp Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 8. Verify the scan tool Front Fog Lamp Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the headlamp switch.

Fog Lamp PCB Relay Circuit Test

  1. Ignition OFF, disconnect the (C2) harness connector at the underhood fuse block.
  2. Connect a test lamp between the control circuit terminal 23 and B+.
  3. Ignition ON, command the Fog Lamps 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 ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the underhood fuse block.

Fog Lamps Circuit Test

  1. Ignition OFF, disconnect the harness connector at the inoperative fog lamp.
  2. Test for less than 5.0 ohms of resistance between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the supply voltage circuit terminal C and the ground circuit terminal A.
  4. Ignition ON, command the Fog Lamps 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 ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    • 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 underhood fuse block.
  5. If all circuits test normal, test or replace the inoperative fog lamp bulb.

Front Fog Lamp Indicator Test

  1. Ignition ON, with a scan tool perform the display test for the instrument panel cluster (IPC) and observe the front fog lamp indicator.
    • If the front fog lamp indicator illuminates during the test, replace the BCM.
    • If the front fog lamp indicator does not illuminate during the test or remains illuminated at all times, replace the IPC.
scientia non olet · About LEMON Manuals