B2529

Step 1: Perform visual inspection of left rear turn signal bulb and socket for obvious damage, corrosion, or burned filament. Remove bulb and inspect socket terminals for heat damage, corrosion, or bent contacts.

Step 2: Using a multimeter, check for battery voltage at the lamp socket connector with turn signal activated. Test both the power feed wire and verify ground circuit continuity to chassis (should be less than 0.5 ohms resistance).

Step 3: If voltage is present at socket, install known-good bulb to confirm socket and power supply are functional. If no voltage present, backprobe along the wiring harness toward BCM checking for voltage at intermediate connectors to isolate break location.

Step 4: Inspect wiring harness for physical damage, pinched wires, or chafing points, particularly in areas where harness passes through body panels or near suspension components. Check connectors for proper seating and terminal tension.

Step 5: If all wiring and connections test good, use scan tool to command left rear turn signal ON and monitor BCM data stream for fault detection or overcurrent conditions. Compare amperage draw to specifications (typically 1.5-2.5 amps for incandescent bulb).

Step 6: After repair, clear codes, cycle turn signals through complete operation, and verify DTC does not return. Perform bulb-out detection test by activating turn signals and confirming BCM recognizes proper operation.