July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Inspection Procedure

CHECK HARNESS AND CONNECTOR (TELEPHONE ECU ASSEMBLY - MAYDAY BATTERY)

Disconnect the P3 ECU connector.
Disconnect the P4 battery connector.
Measure the resistance according to the value(s) in the table below.

Standard Resistance

RESISTANCE SPECIFICATION

Tester Connection	Condition	Specified Condition
P3-2 (BBI+) - P4-1 (BBO+)	Always	Below 1 Ω
P3-9 (BBI-) - P4-2 (BBO-)	Always	Below 1 Ω
P3-2 (BBI+) or P4-1 (BBO+) - Body ground	Always	10 kΩ or higher
P3-9 (BBI-) or P4-2 (BBO-) - Body ground	Always	10 kΩ or higher

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR THEN CLEAR HISTORIC DTC

Fig 1: Identifying P3 And P4 Connector End View Terminal

G05764782

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to next step

REPLACE MAYDAY BATTERY (BACKUP BATTERY)
1. Replace the mayday battery (See MAYDAY BATTERY ).
2. Perform registration (See REGISTRATION ).
3. Check for DTC again (See DTC CHECK / CLEAR ).
  OK: No DTCs output.
  
  NG: REPLACE TELEPHONE ECU ASSEMBLY THEN PERFORM REGISTRATION
  
  OK: END (MAYDAY BATTERY IS FAULTY; CLEAR HISTORIC DTC) (See DTC CHECK / CLEAR )