DTC 4-7: EMERGENCY, VOL+ or VOL- Button has Connection Error: Procedure

Fig 1: Identifying U46 ECU and W8 Map Light Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the U46 ECU connector.
2. Disconnect the W8 map light connector.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance

   Tester Connection	Specified Condition
   U46-5 (SIGI) - W8-3 (SIGI)	Below 1 Ω
   U46-12 (SIG-) - W8-7 (GND)	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR THEN CLEAR HISTORIC DTC 

OK: Go to next step 

Fig 2: Identifying Mayday Switch Assembly

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the map light.
2. Remove the mayday switch from the map light.
3. Measure the resistance of the switch when each switch is pressed.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   3 (SIGI) - 8 (SIG-)	EMERGENCY button is pressed	305 to 313 Ω
   3 (SIGI) - 8 (SIG-)	VOL+ button is pressed	812 to 831 Ω
   3 (SIGI) - 8 (SIG-)	VOL- button is pressed	1811 to 1848 Ω

NG → REPLACE MAYDAY SWITCH ASSEMBLY THEN CLEAR HISTORIC DTC 

OK: Go to next step 

Fig 3: Identifying Mayday Switch

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Install the mayday switch to the map light.
2. Measure the resistance of the switch when each switch is pressed.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   3 (SIGI) - 7 (SIG-)	EMERGENCY button is pressed	305 to 313 Ω
   3 (SIGI) - 7 (SIG-)	VOL+ button is pressed	812 to 831 Ω
   3 (SIGI) - 7 (SIG-)	VOL- button is pressed	1811 to 1848 Ω

NG → REPLACE MAP LIGHT ASSEMBLY THEN CLEAR HISTORIC DTC 

OK → REPLACE MAYDAY ECU TOGETHER WITH MAYDAY BATTERY AND THEN PERFORM REGISTRATION