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DTC B2577: Headlamp Control Circuit Low: Testing

  1. Perform lighting system diagnostic system check. See LIGHTING SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Turn ignition off. Connect scan tool to DLC. Turn ignition on, with engine off. While listening to headlamp relay, use scan tool to command headlamp relay ON and OFF. If audible clicks are heard at relay signifying that it is turning ON and OFF, go to DIAGNOSTIC AIDS  . If audible clicks are not heard at relay signifying that it is turning ON and OFF, go to next step.
  3. Turn ignition off. Disconnect headlamp relay. Turn ignition on, with engine off. Using a test light connected to ground, probe headlamp relay terminal A2 (Orange wire). See appropriate HEAD LIGHTS wiring diagram. If test light illuminates, go to next step. If test light does not illuminate, go to step  10 .
  4. Connect test light between headlamp relay terminals A2 (Orange wire) and C2 (White wire). Using scan tool, command headlamp relay ON and OFF. If test light illuminates each time relay is turned ON and OFF, go to step  8 . If test light does not illuminate each time relay is turned ON and OFF, go to next step.
  5. If test light stays illuminated each time relay is turned ON and OFF in above step, go to step  7 . If test light does not stay illuminated each time relay is turned ON and OFF in above step, go to next step.
  6. Test White wire between headlamp relay terminal C2 and BCM harness connector C3 terminal A11 for short to voltage or an open. See WIRING DIAGRAMS  . After repair, go to step  13 . If fault is not located and condition still exists, go to step  9 .
  7. Test White wire between headlamp relay terminal C2 and BCM harness connector C3 terminal A11 for short to ground. See WIRING DIAGRAMS  . After repair, go to step  13 . If fault is not located and condition still exists, go to step  9 .
  8. Inspect for poor connections at headlamp relay. After repair, go to step  13 . If fault is not located and condition still exists, go to step  11 .
  9. Inspect for poor connections at BCM harness connector C3. After repair, go to step  13 . If fault is not located and condition still exists, go to step  12 .
  10. Repair Orange wire between headlamp relay terminal A2 and fuse block. See appropriate HEADLIGHTS wiring diagram. After repair, go to step  13 .
  11. Replace headlamp relay. After replacement, go to step  13 .
  12. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. After replacement, perform set up procedure. See NEW BCM SETUP  under PROGRAMMING. After replacement, go to next step.
  13. Using scan tool, clear BCM DTCs. Operate vehicle within conditions to set DTC. If DTC B2577 resets, return to step  2 . If DTC B2577 does not reset, system is okay.
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