Navigation System Symptom Troubleshooting - Interface dial buttons do not work
  1. Check for continuity between navigation unit connector A (20P) terminal No. 17 and interface dial 5P connector terminal No. 1.
Is there continuity?
YES -
Check for an open in the wire between the navigation unit connector A (20P) terminal No. 19 and the interface dial 5P connector terminal No. 2. If the wire is OK, go to Step 10 . If the wire is open, repair the wire.■
NO -
There is an open in the circuit between the interface dial and the navigation unit. Check for poor connections or loose terminals at the interface dial and navigation unit. If a poor connection or loose terminals is found, replace the affected shielded harness.■
  1. Substitute a known-good interface dial, and recheck.
Is the system OK?
YES -
Replace the original interface dial. ■
NO -
Replace the navigation unit. ■