DTC B1242: Wireless Door Lock Tuner Circuit Malfunction: Procedure

1. Disconnect the E61 main body ECU connector and the M12 door control receiver connector.
   Fig 1: Identifying E61 Main Body ECU And M12 Door Control Receiver Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   E61-16 (RDA) - M12-2 (RDA)	Always	Below 1 Ω
   E61-16 (RDA) - Body ground	Always	10 kΩ or higher
   E61-17 (PRG) - M12-3 (PRG)	Always	Below 1 Ω
   E61-17 (PRG) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Measure the voltage and resistance according to the value(s) in the table below.
   Fig 2: Identifying Door Control Receiver Connector Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard

   Tester Connection	Condition	Specified Condition
   M12-1 (GND) - Body ground	Always	Below 1 Ω
   M12-5 (+B) - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Temporarily replace the door lock control receiver with a new or known good one. Refer to REMOVAL .

NEXT: Go to next step 

1. Perform the Registration procedure. Refer to REGISTRATION .

NEXT: Go to next step 

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
2. Check if the same DTC is detected.

   Result

   Result	Proceed to
   DTC is not output	A
   DTC is output	B

B → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK) 

A → END (DOOR CONTROL RECEIVER IS DEFECTIVE)