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Tahoe / Yukon Service Manual

DTC B1A58 or B1A59

Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC B1A58 49 Left Headlamp Internal Malfunction DTC B1A59 49 Right Headlamp Internal Malfunction Symptom Byte List Circuit/System Description Each headlamp assembly has internal logic that monitors the components within the headlamp assembly. When a fault within the headlamp assembly is detected, the K9 Body Control Module will set the appropriate DTC against the appropriate headlamp assembly. Diagnostic Aids No parts are serviceable within the headlamp assemblies so complete headlamp assembly replacement is necessary. Conditions for Running the DTC Battery voltage must be between 9–16 V. Conditions for Setting the DTC DTC B1A58 49 The K9 Body Control Module detects an internal malfunction within the left headlamp assembly. DTC B1A59 49 The K9 Body Control Module detects an internal malfunction within the right headlamp assembly. Conditions for Clearing the DTC The condition responsible for setting the DTC no longer exists. A history DTC will clear once 40 consecutive malfunction-free ignition cycles have occurred. Reference Information Schematic Reference Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference Master Electrical Component List Description and Operation Exterior Lighting Systems Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Ignition ON.
  2. Verify no related DTCs are set. ⇒ If a related DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Verify DTC B1A58 49 or B1A59 49 is not set. ⇒ If DTC B1A58 49 or B1A59 49 is set 3.1. Replace the appropriate E13 Headlamp Assembly. ⇓ If DTC B1A58 49 or B1A59 49 is not set
  4. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Lighting Component Replacement Reference Control Module References for Headlamp Leveling Control Module replacement, programming, and setup