What does it mean?
B1603 is a Body (airbags, seat belts, body electronics) fault code. It indicates: CAN Communication Bus (Assist Door Module) .
Symptoms
- The theft or security indicator never lights, or stays lit continuously
- No bulb check flash on switching the ignition on
- The driver cannot tell whether the alarm is armed or disarmed
- Other cluster indicators work normally, which narrows the fault to this one circuit
- On the bus variant, passenger door window, lock and mirror functions stop working and the door module does not respond to the scan tool
Likely causes
- Burnt out or unseated theft indicator bulb or LED in the instrument cluster
- Cracked solder joint on the cluster board at the indicator driver
- Open or chafed wire between the module and the indicator
- Corroded or partly seated cluster connector
- Module output driver failure
- Poor cluster ground affecting the indicator circuit only
- On applications where this code refers to the data bus, an open, short or missing termination on the link to the passenger door module, or lost power and ground at that module
How to fix it
- Command the indicator with the scan tool output test and watch the cluster, which immediately shows whether the module or the display side is at fault
- Check the bulb or LED and its socket in the cluster
- Measure the indicator circuit at the module for an open, first with the cluster connected and then disconnected
- Inspect the cluster connector for pushed-back and corroded terminals
- Verify the cluster power and ground before condemning the cluster itself
- Repair the wiring before replacing the cluster or the module
- On the bus variant, check power and ground at the passenger door module first, then measure bus resistance and inspect the loom in the door hinge boot for a break