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Home >> Cadillac >> 2018 >> Escalade ESV Platinum, RWD >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System - DTC B0655 To DTC B3951 >> Diagnostic Information And Procedures >> DTC B3948 Or B3949: Left/Right Front Turn Signal Circuit >> Circuit/System Testing

Circuit/System Testing

DTC B3948

  1. Ignition OFF, exterior lamps OFF, All doors closed, open and close drivers door, disconnect the appropriate component listed below. It may take up to 2 min for all vehicle systems to power down.
    • A9A Outside Rearview Mirror - Driver (DR4)
    • E4LF Turn Signal Lamp - Left Front (Z75/X88)
    • E13LA Headlamp Assembly - Left
    • A17D Outside Rearview Mirror Glass - Driver (DL3)
  2. Test for less than 15 Ω between the appropriate ground circuit terminal listed below and ground.
    • A9A Outside Rearview Mirror - Driver terminal 5 (DR4)
    • E4LF Turn Signal Lamp - Left Front terminal 2 (Z75/X88)
    • E13LA Headlamp Assembly - Left terminals 1 and 4
    • A17D Outside Rearview Mirror Glass - Driver terminal 2 (DL3)
    • 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.
    • A9A Outside Rearview Mirror - Driver terminal 13 (DR4)
    • E4LF Turn Signal Lamp - Left Front terminal 1 (Z75/X88)
    • E13LA Headlamp Assembly - Left terminals 5
    • A17D Outside Rearview Mirror Glass - Driver terminal 1 (DL3)
  4. Verify the test lamp turns ON and OFF when commanding the Left Front Turn Signal Lamp ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit 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, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, 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 K9 Body Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Test or replace the appropriate turn signal lamp - left.

DTC B3949

  1. Ignition OFF, exterior lamps OFF, All doors closed, open and close drivers door, disconnect the appropriate component listed below. It may take up to 2 min for all vehicle systems to power down.
    • A9B Outside Rearview Mirror - Passenger (DR4)
    • E4RF Turn Signal Lamp - Right Front (Z75/X88)
    • E13RA Headlamp Assembly - Right
    • A17P Outside Rearview Mirror Glass - Passenger (DL3)
  2. Test for less than 15 Ω between the appropriate ground circuit terminal listed below and ground.
    • A9B Outside Rearview Mirror - Passenger terminal 5 (DR4)
    • E4RF Turn Signal Lamp - Right Front terminal 2 (Z75/X88)
    • E13RA Headlamp Assembly - Right terminals 1 and 4
    • A17P Outside Rearview Mirror Glass - Passenger terminal 2 (DL3)
    • 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.
    • A9B Outside Rearview Mirror - Passenger terminal 13 (DR4)
    • E4RF Turn Signal Lamp - Right Front terminal 1 (Z75/X88)
    • E13RA Headlamp Assembly - Right terminals 5
    • A17P Outside Rearview Mirror Glass - Passenger terminal 1 (DL3)
  4. Verify the test lamp turns ON and OFF when commanding the Right Front Turn Signal Lamp ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X4 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit 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, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X4 harness connector at the K9 Body Control Module, 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 K9 Body Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Test or replace the appropriate turn signal lamp - right.
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