Fault code 1503: Diagnosis/troubleshooting
NOTE:
Visual inspection: In the next troubleshooting section, please check first that the affected pins on the rear convenience system control unit plug connection are neither damaged nor corroded. The wiring and plugs of the affected components must also be checked for external damage and correct contacts. Repair damaged or corroded pins if possible, otherwise replace affected pins. Repair or replace damaged wires.
NOTE:
Sporadic faults: In the event of faults that occur sporadically, the wiring positions that are linked to moving parts on and in the vehicle must be checked for each system. Various statuses that can cause faults must be simulated with the help of the wiring diagram.
NOTE:
Battery voltage: A battery voltage of between 11.4 and 14.5 V is required for the following troubleshooting procedure. This must be checked and provided, if necessary. On the vehicle electrical system, the voltage to the fuse (input side) must be guaranteed.
NOTE:
The conducting direction must be observed for LEDs.
NOTE:
In the rear lid area of the wiring harness there is a 6-pin connector that must be included in the checks.
WORK INSTRUCTION CHART
| Work instruction | Display OK | If not OK | ||
|---|---|---|---|---|
| 1 | Check wiring for short circuit to B+ |
|
< 0.3 V Go to step 2 |
Check and if necessary repair pin 5 of the 6-pin connector. Repair wiring. → End |
| 2 | Check wiring for short circuit to ground |
|
∞ Ω Go to step 3 |
Check and if necessary repair pin 5 of the 6-pin connector. Repair wiring. → End |
| 3 | Check wiring for open circuit |
|
< 5 Ω Go to step 4 |
Check and if necessary repair pin 5 of the 6-pin connector. Repair wiring. → End |
| 4 | Replace additional brake light | → End | Remove additional brake light again. Go to step 5 |
|
| 5 | Replace rear convenience system control module | → End | ||