Inspection Procedure

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

   Switch position	Tester connection	Specified condition
   Service Play back Record	6-8	Continuity
   Emergency Volume UP Volume DOWN	3-6	Continuity

   OK: 

   There is a continuity when switch is pressed, and no continuity when not pressed. 

   Fig 1: Inspecting Telephone Switch Assembly (Mayday Assembly)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

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

HINT:

If DTC is not cleared even through the Mayday ECU is replaced, replace the Mayday Assembly (Transceiver, Back-up battery, Bus buffer ECU and Mayday ECU).