Circuit/System Testing
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
WARNING:
The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:
- Never open the high intensity discharge system ballast or the arc tube assembly starter.
- Never probe between the high intensity discharge system ballast output connector and the arc tube assembly.
Headlamp Switch Malfunction
- Ignition OFF, disconnect the harness connector at the headlamp switch.
- 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.
- Ignition ON, verify the scan tool Parklamp Switch parameter is Inactive.
- If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
- Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Parklamp 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.
- If all circuits test normal, test or replace the headlamp switch.
Park, License, and/or Tail Lamps Malfunction - All Countries Except Japan, Korea, Taiwan
- Ignition OFF, disconnect the PRK LAMP relay from the rear fuse block.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 104 and ground.
- If the test lamp illuminates, test the control circuits for a short to voltage.
- Verify that a test lamp illuminates between the B+ circuit terminal 102 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Verify that a test lamp illuminates between the B+ circuit terminal 100 and ground.
- If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
- Connect a test lamp between the B+ circuit terminal 102 and the control circuit terminal 101.
- Command the parking 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.
- Disconnect the harness connector at the inoperative lamp.
- Ignition OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground:
- Front park and marker lamp terminal A
- Tail lamp terminal C
- License lamp terminal B
- Middle park lamp terminal B (V4U)
- Rear park lamp terminal B (V4U or B9Q)
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the inoperative lamp control circuit terminal listed below and ground:
- Front park and marker lamp terminal B
- Tail lamp terminal F
- License lamp terminal A
- Middle park lamp terminal A (V4U)
- Rear park lamp terminal A (V4U or B9Q)
- Connect a 3A fused jumper wire between the B+ circuit terminal 100 and the control circuit terminal 104. Verify the test lamp is illuminated.
- If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the bulb or lamp assembly.
- If all circuits test normal, test or replace the park lamp relay.
Park, and/or Tail Lamps Malfunction - Japan, Korea, Taiwan Only
- Ignition OFF, disconnect the appropriate PRK LAMP relay or the RT PRK LAMP relay from the rear fuse block.
- Ignition ON, verify that a test lamp does not illuminate between the appropriate control circuit terminal listed below and ground:
- PRK LAMP relay terminal 104
- RT PRK LAMP relay terminal 94
- If the test lamp illuminates, test the control circuits for a short to voltage.
- Verify that a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground:
- PRK LAMP relay terminal 102
- RT PRK LAMP relay terminal 90
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Verify that a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground:
- PRK LAMP relay terminal 100
- RT PRK LAMP relay terminal 93
- If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
- Connect a test lamp between the appropriate B+ circuit terminal and the control circuit terminal listed below:
- PRK LAMP relay terminal 102 and terminal 101
- RT PRK LAMP relay terminal 93 and terminal 92
- Command the parking 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.
- Disconnect the harness connector at the inoperative lamp.
- Ignition OFF, test for less than 5.0 ohms between the appropriate ground circuit listed below and ground:
- Front park and marker lamp terminal A
- Tail lamp terminal H
- License lamp terminal B
- Middle park lamp terminal B (V4U)
- Rear park lamp terminal B (V4U or B9Q)
- Position lamp terminal A (T72)
- Position lamp terminal H (T84)
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the inoperative lamp control circuit listed below and ground:
- Front park and marker lamp terminal B
- Tail lamp terminal F
- License lamp terminal A
- Middle park lamp terminal A (V4U)
- Rear park lamp terminal A (V4U or B9Q)
- Position lamp terminal G
- Connect a 3A fused jumper wire between the appropriate relay B+ circuit terminal and the control circuit terminal listed below. Verify the test lamp is illuminated.
- PRK LAMP relay terminal 100 and terminal 104
- RT PRK LAMP relay terminal 90 and terminal 94
- If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the bulb or the lamp assembly.
- If all circuits test normal, test or replace the park lamp relay.
License Lamp Malfunction - Japan, Korea, Taiwan Only
- Ignition OFF, disconnect the EXP LIC LAMP relay from the rear fuse block.
- Ignition OFF, test for less than 5 ohms between the ground circuit terminal 9 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 10 and ground.
- If the test lamp illuminates, test the control circuit for a short to voltage.
- Park lamps ON, verify that a test lamp illuminates between the control circuit terminal 6 and ground.
- If the test lamp does not illuminate, test the control circuit for an open/high resistance.
- Park lamps ON, verify that a test lamp illuminates between the control circuit terminal 8 and ground.
- If the test lamp does not illuminate, test the control circuit for an open/high resistance.
- Ignition OFF, disconnect the harness connector at the inoperative license lamp.
- Ignition OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the control circuit terminal A and ground.
- Connect a 3A fused jumper wire between the relay control circuit terminal 10 and B+. The test lamp should illuminate.
- If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the bulb or the lamp assembly.
- If all circuits test normal, test or replace the EXP LIC LAMP relay.