STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
STEP 2. DTC recheck after resetting CAN bus lines
STEP 3. Brake pedal check
STEP 4. Check whether the other system DTC is stored.
STEP 5. Check for stoplight switch installation
STEP 6. Stoplight switch continuity check
STEP 8. Brake booster check
STEP 9. Check whether the DTC is stored again.
STEP 10. Check whether the DTC is stored again.