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Home >> Cadillac >> 2018 >> Escalade ESV Platinum, RWD >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting System - DTC C0277 To DTC C0297 And Diagnostic Information And Procedures >> Diagnostic Information And Procedures >> Backup Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, exterior lamps OFF, all doors closed, open and close drivers door, disconnect the appropriate harness connector listed below. It may take up to 2 min for all vehicle systems to power down.
    • E5A Backup Lamp - Left (X88/Z88)
    • E5B Backup Lamp - Right (X88/Z88)
    • E42L Tail Lamp Assembly - Left (Z75)
    • E42R Tail Lamp Assembly - Right (Z75)
  2. Test for less than 15 Ω between the appropriate ground circuit terminal listed below and ground.
    • E5A Backup Lamp - Left socket terminal (X88/Z88)
    • E5B Backup Lamp - Right socket terminal (X88/Z88)
    • E42L Tail Lamp Assembly - Left terminal 6 (Z75)
    • E42R Tail Lamp Assembly - Right socket terminal 6 (Z75)
    • If 15 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 15 Ω 
  3. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
    • E5A Backup Lamp - Left socket terminal (X88/Z88)
    • E5B Backup Lamp - Right socket terminal (X88/Z88)
    • E42L Tail Lamp Assembly - Left terminal 1 (Z75)
    • E42R Tail Lamp Assembly - Right socket terminal 1 (Z75)
  4. Verify the test lamp does not turn ON and OFF when commanding the Backup Lamps ON and OFF with a scan tool.
    • If the test lamp turns ON and OFF 
    • Test or replace the E5 Backup Lamp (X88/Z88) or E42 Tail Lamp Assembly (Z75).
    • Go to next step: If the test lamp does not turn ON and OFF 
  5. Ignition OFF, connect the E5 Backup Lamp (X88/Z88) or E42 Tail Lamp Assembly (Z75).
  6. Disconnect the X5 harness connector at the X50A Fuse Block - Underhood, ignition ON.
  7. Verify the backup lamps do not illuminate.
    • If the backup lamps illuminate 
    1. Ignition OFF, disconnect the appropriate E5 Backup Lamp (X88/Z88) or E42 Tail Lamp Assembly (Z75), ignition ON.
    2. Test for less than 1 V between the appropriate control circuit terminal listed below and ground.
      • E5A Backup Lamp - Left socket terminal (X88/Z88)
      • E5B Backup Lamp - Right socket terminal (X88/Z88)
      • E42L Tail Lamp Assembly - Left terminal 1 (Z75)
      • E42R Tail Lamp Assembly - Right socket terminal 1 (Z75)
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the E5 Backup Lamp (X88/Z88) or E42 Tail Lamp Assembly (Z75).
    • Go to next step: If the backup lamps do not illuminate 
  8. Ignition OFF, connect a 3 A fused jumper between the control circuit terminal C1 and B+, ignition ON.
  9. Verify the backup lamps illuminate.
    • If the backup lamps do not illuminate 
    1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the appropriate E5 Backup Lamp (X88/Z88) or E42 Tail Lamp Assembly (Z75).
    2. Test for infinite resistance between the control circuit terminal C1 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, all OK.
    • Go to next step: If the backup lamps illuminate 
  10. Ignition OFF, all vehicle systems OFF, disconnect the X2 Harness connector at the X50A Fuse Block - Underhood. It may take up to 2 min for all vehicle systems to power down.
  11. Test for less than 10 Ω between the ground circuit terminal F2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 Ω 
  12. Connect the X2 and X5 harness connectors at the X50A Fuse Block - Underhood.
  13. Disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  14. Verify a test lamp illuminates between the control circuit terminal 26 and B+.
    NOTE: The test lamp will illuminate at low intensity for the following test.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X4 harness connector at the X50A Fuse Block - Underhood, ignition ON.
    2. Test for less than 1 V between the control circuit terminal 26 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  15. Connect a 3 A fused jumper between the control circuit terminal 26 and B+, ignition ON.
  16. Verify the backup lamps illuminate.
    • If the backup lamps do not illuminate 
    1. Ignition OFF, disconnect the X4 harness connector at the X50A Fuse Block - Underhood.
    2. Test for infinite resistance between the control circuit terminal 26 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the backup lamps illuminate 
  17. Test or replace the K9 Body Control Module.
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