Inspection Procedure

1. Disconnect the O2 telephone switch connector.
2. Check that the continuity exists between the terminals of the switch when each switch is pressed.

   Standard: 

   SPECIFIED CONDITION
   
   

   Terminal No.	Switch Condition	Specified Condition
   4-14	Service Play back Record	Continuity
   4-13	Emergency Volume UP Volume DOWN	Continuity

   Fig 1: Inspecting Telephone Switch Assy (Mayday Switch)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. NG: REPLACE TELEPHONE SWITCH ASSY 
2. OK: GO TO NEXT STEP 

1. NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 
2. OK: REPLACE TELEPHONE ECU ASSY (MAYDAY ECU) 

HINT: 

If this DTC is not cleared even when the mayday ECU is replaced, replace the mayday assy (transceiver, portable phone-L battery (back-up battery), bus buffer ECU and mayday ECU).