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)

CHECK HARNESS AND CONNECTOR (DOOR CONTROL RECEIVER - ELECTRICAL KEY ANTENNA)

CHECK AND REPLACE DOOR CONTROL RECEIVER (RECONFIRM DTC)

CHECK AND REPLACE ELECTRICAL KEY ANTENNA (RECONFIRM DTC)

INSPECT CERTIFICATION ECU

DTC B1242 Wireless Door Lock Tuner Circuit Malfunction


DESCRIPTION

  1. The electrical key antenna and the door control receiver are used as antennas for the entry and wireless door lock functions of the entry and start system.
  2. The certification ECU 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. The 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
    		If the certification ECU detects that terminal RDA or RSSI is short-circuited, this DTC is stored.
    1. Electrical Key Antenna
    2. Door Control Receiver
    3. Wire harness
    4. 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 ECU connector.

  1. Disconnect the P31 receiver connector.

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

    Standard resistance:
    Tester Connection (Symbols)
    		Condition
    		Specified Condition
    P33-37 (ASEL) - P31-4 (ASEL)
    		Always
    		Below 1 Ω
    P33-39 (RSSI) - P31-5 (RSSI)
    		Always
    		Below 1 Ω
    P33-38 (RDA) - P31-3 (DATA)
    		Always
    		Below 1 Ω
    P33-29 (RCO) - P31-2 (+5)
    		Always
    		Below 1 Ω
    P33-37 (ASEL) - Body ground
    		Always
    		10 kΩ or higher
    P33-39 (RSSI) - Body ground
    		Always
    		10 kΩ or higher
    P33-38 (RDA) - Body ground
    		Always
    		10 kΩ or higher
    P33-29 (RCO) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.CHECK HARNESS AND CONNECTOR (DOOR CONTROL RECEIVER - ELECTRICAL KEY ANTENNA)


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

  1. Disconnect the P20 antenna connector.

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

    HINT:
    Perform the measurement with the P31 receiver connector disconnected.
    Standard resistance:
    Tester Connection
    (Symbols)
    		Condition
    		Specified Condition
    P31-7 (ANT) - P20-1 (ANT)
    		Always
    		Below 1 Ω
    P31-7 (ANT) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.CHECK AND REPLACE DOOR CONTROL RECEIVER (RECONFIRM DTC)

  1. Replace the receiver.

  1. Clear the DTC and repeat the procedure to re-check for DTCs (Click here).

    OK:
    DTC is not output.


OK
END (RECEIVER IS DEFECTIVE)
NG


4.CHECK AND REPLACE ELECTRICAL KEY ANTENNA (RECONFIRM DTC)

  1. Replace the antenna.

  1. Clear the DTC and repeat the procedure to re-check for DTCs (Click here).

    OK:
    DTC is not output.


OK
END (ANTENNA IS DEFECTIVE)
NG


5.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. Reconnect the P20 antenna connector.

  1. Reconnect the P31 receiver connector.

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

    Standard voltage:
    Tester Connection
    (Symbols)
    		Condition
    		Specified Condition
    P33-37 (ASEL) - Body ground
    		Engine switch OFF, luggage compartment door OPEN
    		Below 1 V
    Engine switch OFF, luggage compartment door CLOSE
    		4.6 to 5.4 V
    P33-39 (RSSI) - Body ground
    		Engine switch OFF, all doors closed, the electrical key is not in the action area
    		10 to 14 V
    Engine switch OFF, all doors closed, the electrical key in the action area
    		Below 1 V
    P33-38 (RDA) -Body ground
    		Engine switch OFF, all doors closed and electrical key switch OFF
    		10 to 14 V
    Engine switch OFF, all doors closed and electrical key switch ON
    		Pulse generation
    P33-29 (RCO) - Body ground
    		Engine switch OFF, all doors closed and electrical key switch OFF
    		Below 1 V
    Engine switch OFF, all doors closed and electrical key switch ON
    		4.6 to 5.4 V


NG
REPLACE CERTIFICATION ECU
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE