1. Check for continuity between following terminals of the hands free telephone control unit connector (22P) and the navigation unit connector C (14P).

   22P: | 14P:
   --- | ---
   No. 21 | No. 6
   No. 22 | No. 13

Is there continuity?

YES | - | Substitute a known-good hands free telephone control unit, then recheck. If the symptom goes away, replace the original hands free telephone control unit. If the symptom does not away, replace the faulty navigation unit.■
NO | - | Repair open the wires between the hands free telephone control unit and the navigation unit.■