Dtc B1242 Wireless Door Lock Tuner Circuit Malfunction

Body Electrical. Lexus Is250, Is220D. Gse20 Ale20
Door Lock. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

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

INSPECT CERTIFICATION ECU

REPLACE DOOR CONTROL RECEIVER

DTC B1242 Wireless Door Lock Tuner Circuit Malfunction


DESCRIPTION

  1. The electrical key antenna is used to receive electric waves relating to the entry functions of the smart access system with push-button start. The certification ECU decodes the requested smart access system with push-button start 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 RH through the certification ECU.
  3. The certification ECU 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 RH.)

DTC No.
DTC Detection Condition
Trouble Area
B1242
The certification ECU detects that there is a short in the circuit between terminals RSSI, or between terminals DATA and RDA.
  1. Door Control Receiver
  2. Wire harness
  3. Certification ECU

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.Door Lock.Power Door Lock Control System. Dtc B1242 Wireless Door Lock Tuner Circuit Malfunction


INSPECTION PROCEDURE

1.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - DOOR CONTROL RECEIVER)
Lexus Is250, Is220D. Gse20 Ale20.Door Lock.Power Door Lock Control System. Dtc B1242 Wireless Door Lock Tuner Circuit Malfunction

  1. Disconnect the P33 certification ECU connector and P31 door control receiver connector.

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

Standard resistance:
Symbol
(Tester Connection)
Condition
Specified Condition
RSSI (P33-39) - RSSI (P31-5)
Always
Below 1 Ω
RDA (P33-38) - DATA (P31-3)
Always
Below 1 Ω
RSSI (P33-39) - RDA (P33-38)
Always
10 kΩ or higher
RSSI (P33-39) - Body ground
Always
10 kΩ or higher
RDA (P33-38) - Body ground
Always
10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.INSPECT CERTIFICATION ECU
Lexus Is250, Is220D. Gse20 Ale20.Door Lock.Power Door Lock Control System. Dtc B1242 Wireless Door Lock Tuner Circuit Malfunction

  1. Reconnect the P33 ECU connector.

  1. Measure the voltage according to the value(s) in the table below.

Standard voltage:
Symbol
(Tester Connection)
Condition
Specified Condition
RSSI (P33-39) - E (P33-17)
Engine switch OFF, all doors closed, the electrical key is not the actuation area
Below 1 V
Engine switch OFF, all doors closed, the electrical key is the actuation area
4.6 to 5.4 V
RDA (P33-38) - E (P33-17)
Engine switch OFF, all doors closed and transmitter switch not pressed
Below 1 V
Engine switch OFF, all doors closed and transmitter switch pressed
4.6 to 5.4 V


NG
REPLACE CERTIFICATION ECU
OK


3.REPLACE DOOR CONTROL RECEIVER

  1. Replace the door control receiver with normal one

  1. Perform the registration procedure.

    OK:
    The system returns to normal operation.


NG
REPLACE CERTIFICATION ECU
OK

END