LEMON Manuals: Even more car manuals for everyone
Home >> Cadillac >> 2018 >> XT5 Platinum >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System - Diagnostic Information And Procedures (DTC B3950 - C0297) >> Diagnostic Information and Procedures >> Trailer Lamps Malfunction (Without U4G) >> Circuit/System Testing

Circuit/System Testing

Trailer Backup Lamps Malfunction (with U4G/V92)

  1. Ignition OFF, exterior lamps OFF.
  2. Test for less than 10 Ω between the ground circuit terminal B at the X88 Trailer Connector 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 
  3. Disconnect the X2 harness connector at the X53A Fuse Block - Rear Body.
  4. Test for less than 10 Ω between the ground circuit terminal 34 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 
  5. Connect the X2 harness connector at the X53A Fuse Block - Rear Body.
  6. Connect a test lamp between the control circuit terminal A at the X88 Trailer Connector and ground, ignition ON.
  7. Verify the test lamp turns ON and OFF when commanding the Backup Lamps ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X1 harness connector at the X53A Fuse Block - Rear Body.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, replace the X53A Fuse Block - Rear Body.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X1 harness connector at the X53A Fuse Block - Rear Body, ignition ON.
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X53A Fuse Block - Rear Body.
    • Go to next step: If the test lamp turns ON and OFF 
  8. Test or replace the X88 Trailer Connector.

Trailer Park Lamps Malfunction

  1. Ignition OFF, exterior lamps OFF.
  2. Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
    • X88 Trailer Connector terminal B (heavy duty)
    • X88 Trailer Connector terminal D (light duty)
    • 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 
  3. Disconnect the X1 harness connector at the X50A Fuse Block - Underhood, ignition ON.
  4. Verify a test lamp does not illuminate between the control circuit terminal 37 and ground.
    • If the test lamp illuminates 
    1. Ignition ON.
    2. Test for less than 1 V between the control circuit terminal 37 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the trailer connector.
    • Go to next step: If the test lamp does not illuminate 
  5. Ignition OFF, connect a 3 A fused jumper between the control circuit terminal 37 and B+, ignition ON.
  6. Verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
    • X88 Trailer Connector terminal F (heavy duty)
    • X88 Trailer Connector terminal A (light duty)
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the 3 A fused jumper wire.
    2. Test for infinite resistance between the control circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, replace the trailer connector.
    • Go to next step: If the test lamp illuminates 
  7. Ignition OFF, connect the X1 harness connector at the X50A Fuse Block - Underhood.
  8. Disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  9. Verify a test lamp illuminates between the control circuit terminal 22 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  10. Connect a 3 A fused jumper between the control circuit terminal 22 and ground, ignition ON.
  11. Verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
    • X88 Trailer Connector terminal F (heavy duty)
    • X88 Trailer Connector terminal A (light duty)
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood, ignition ON.
    2. Test for less than 1 V between the control circuit terminal 22 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  12. Test or replace the K9 Body Control Module.

Trailer Stop/Turn Signal Lamps Malfunction

  1. Ignition OFF, exterior lamps OFF.
  2. Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
    • X88 Trailer Connector terminal B (heavy duty)
    • X88 Trailer Connector terminal D (light duty)
    • 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 
  3. Disconnect the X1 harness connector at the X50A Fuse Block - Underhood, ignition ON.
  4. Verify a test lamp does not illuminate between the appropriate control circuit terminal listed below and ground.
    • Terminal 29 - left stop/turn signal
    • Terminal 35 - right stop/turn signal
    • If the test lamp illuminates 
    1. Ignition ON.
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the trailer connector.
    • Go to next step: If the test lamp does not illuminate 
  5. Ignition OFF, connect a 3 A fused jumper between the appropriate control circuit terminal listed below and B+, ignition ON.
    • Terminal 29 - left stop/turn signal
    • Terminal 35 - right stop/turn signal
  6. Verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
    • X88 Trailer Connector terminal G - left stop/turn signal (heavy duty)
    • X88 Trailer Connector terminal D - right stop/turn signal (heavy duty)
    • X88 Trailer Connector terminal B - left stop/turn signal (light duty)
    • X88 Trailer Connector terminal C - right stop/turn signal (light duty)
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the 3 A fused jumper wire.
    2. Test for infinite resistance between the control circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, replace the trailer connector.
    • Go to next step: If the test lamp illuminates 
  7. Ignition OFF, connect the X1 harness connector at the X50A Fuse Block - Underhood.
  8. Disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  9. Verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
    • Terminal 8 - left stop/turn signal
    • Terminal 17 - right stop/turn signal
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  10. Connect a 3 A fused jumper between the appropriate control circuit terminal listed below and ground, ignition ON.
    • Terminal 8 - left stop/turn signal
    • Terminal 17 - right stop/turn signal
  11. Verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
    • X88 Trailer Connector terminal G - left stop/turn signal (heavy duty)
    • X88 Trailer Connector terminal D - right stop/turn signal (heavy duty)
    • X88 Trailer Connector terminal B - left stop/turn signal (light duty)
    • X88 Trailer Connector terminal C - right stop/turn signal (light duty)
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood, ignition ON.
    2. Test for less than 1 V between the appropriate control circuit terminal listed below and ground.
      • Terminal 8 - left stop/turn signal
      • Terminal 17 - right stop/turn signal
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  12. Test or replace the K9 Body Control Module.
scientia non olet · About LEMON Manuals