B2251

Step 1: Perform visual inspection of parking lamp relay, relay socket, and associated wiring for obvious damage, corrosion, burnt terminals, or loose connections. Check relay socket for signs of overheating or melted plastic.

Step 2: Remove parking lamp relay and test relay operation using a multimeter. Check coil resistance (typically 70-120 ohms) across relay coil terminals. Apply 12V to coil terminals and verify audible click and continuity through relay contacts.

Step 3: With relay removed, use multimeter to measure voltage at relay control terminal from BCM while commanding parking lamps on via scan tool bidirectional controls. Should see battery voltage or ground signal depending on relay type (typically ground-switched).

Step 4: Check for short to ground or power on relay driver circuit by disconnecting BCM connector and measuring resistance between relay control pin and ground, then relay control pin and battery positive. Should read open circuit (>10k ohms) in both cases.

Step 5: Install known-good relay and command parking lamps on. If system operates correctly, replace original relay. If fault persists, check for excessive current draw in parking lamp circuits by measuring amperage at relay output.

Step 6: If all external circuits test normal but fault remains, suspect failed BCM relay driver. Verify all BCM ground connections are clean and tight before condemning BCM. Clear codes and verify repair by cycling parking lamps multiple times.