Dtc B1242 Wireless Door Lock Tuner Circuit Malfunction

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - DOOR CONTROL RECEIVER)

INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

DESCRIPTION

1. The electrical key antenna is used to receive electric waves relating to the entry functions of the entry and start system. The certification ECU (smart key ECU assembly) decodes the requested entry and start system operation by identifying a key code based on electric waves received via the electrical key antenna and the door control receiver.
   
2. The door control receiver receives a signal from the wireless door control transmitter and sends signals to the main body ECU through the certification ECU (smart key ECU assembly).
   
3. The certification ECU (smart key ECU assembly) then sends a command, according to the requested operation, to each ECU. (e.g. If door lock operation is requested, the ECU sends a door lock command to the main body ECU.)
   

WIRING DIAGRAM

INSPECTION PROCEDURE

1. Disconnect the E74 certification ECU (smart key ECU assembly) connector and O27 door control receiver connector.
   

2. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E74-39 (RSSI) - O27-5 (RSSI)	Always	Below 1 Ω
   E74-38 (RDA) - O27-3 (DATA)	Always	Below 1 Ω
   E74-39 (RSSI) - E74-38 (RDA)	Always	10 kΩ or higher
   E74-39 (RSSI) - Body ground	Always	10 kΩ or higher
   E74-38 (RDA) - Body ground	Always	10 kΩ or higher

1. Reconnect the E74 ECU connector.
   

2. Measure the voltage and check for pulse according to the value(s) in the table below.
   

   Standard:

   Tester Connection	Condition	Specified Condition
   E74-29 (RC0) - E74-17 (E)	Engine switch off, all doors closed and transmitter switch not pressed	Pulse generation
   	Engine switch off, all doors closed and transmitter switch pressed	4.6 to 5.4 V