High-Mounted Brake Lamp
The auxiliary brake lamp function can be checked via output diagnostic test mode of Vehicle Electrical System Control Module -J519-.
Diagnostic Trouble Code (DTC) Recognition and Display:
Vehicle Electrical System Control Module -J519- is equipped with On Board Diagnostics (OBD) which assists in troubleshooting.
The "Guided Fault Finding" function is to be used for troubleshooting of one of the systems described as in "Vehicle Diagnosis, Testing and Information System", refer to VEHICLE DIAGNOSIS, TESTING AND INFORMATION SYSTEMS .
LED failure in high-mount brake lamps (not USA and Canada):
Individual LEDs in auxiliary brake lights are combined in groups of up to four and are supplied with power as a row.
The auxiliary brake light is designed so that the regulations from the Economic Commission for Europe are still met if a row of LEDs fails. However, the legal requirements will not be met if an additional LED row fails.
When one LED row fails, the remaining LEDs are given a higher load. However, that can cause those LEDs to fail sooner.
If more than four individual LEDs in the auxiliary brake light have failed, the auxiliary brake light must be replaced.