DTC    B1242    Wireless Door Lock Tuner Circuit Malfunction

for Preparation Click here


DESCRIPTION

The door control receiver receives lock / unlock signals from the transmitter and sends these signals to the main body ECU via the certification ECU using the serial line.
The main body ECU then activates the door lock motor on each door in accordance with these signals.

DTC No.
DTC Detection Condition
Trouble Area
B1242
One of following conditions is met:
  1. Short in RDA or RSSI ground between certification ECU and door control receiver
  2. Short in RDA or RSSI ground when RCO (5 V) output from ECU off
  1. Wire harness
  2. Door control receiver
  3. ECU aggregation box (certification ECU)
  4. Instrument panel junction block (main body ECU)

WIRING DIAGRAM


B131602E01


INSPECTION PROCEDURE

1.CHECK WIRE HARNESS (CERTIFICATION ECU - DOOR CONTROL RECEIVER)
B123844E02

  1. Disconnect the E63 ECU connector.

  1. Disconnect the L13 receiver connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    E63-38 (RDA) - L13-5 (DATA)
    		Below 1 Ω
    E63-39 (RSSI) - L13 (RSSI)
    E63-29 (RCO) - L13-4 (+5)
    E63-38 (RDA) or L13-5 (DATA) - Body ground
    		10 kΩ or higher
    E63-39 (RSSI) or L13 (RSSI) - Body ground
    E63-29 (RCO) or L13-4 (+5) - Body ground


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


2.CHECK WIRE HARNESS (MAIN BODY ECU - CERTIFICATION ECU)
B137711E01

  1. Disconnect the E19 and E63 ECU connectors.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    E19-11 (CANP) - E63-27 (CANH)
    		Below 1 Ω
    E19-12 (CANN) - E63-28 (CANL)
    E19-11 (CANP) or E63-27 (CANH) - Body ground
    		10 kΩ or higher
    E19-12 (CANN) or E63-28 (CANL) - Body ground


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK DOOR CONTROL RECEIVER (+B TERMINAL)
B111368E07

  1. Measure the voltage of the connector.

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    L13-4 (+5) - Body ground
    		Ignition switch off, all doors closed and transmitter switch not pressed → pressed
    		5 to below 1 V → 5 V


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


4.CHECK WIRE HARNESS (DOOR CONTROL RECEIVER - BODY GROUND)
B131604E01

  1. Disconnect the L13 receiver connector.

  1. Measure the resistance of the wire harness side connector.

    Standard resistance:
    Tester Connection
    		Specified Condition
    L13-1 (GND) - Body ground
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


5.REPLACE DOOR CONTROL RECEIVER

  1. Temporarily replace the door control receiver with a new or normally functioning one (Click here, Click here).

  1. Perform the REGISTRATION procedures.


NEXT


6.CHECK FOR DTC

  1. Clear the DTC (Click here).

  1. Check if the same DTC is detected.

    OK:
    DTC B1242 is not output.


OK
END (DOOR CONTROL RECEIVER IS DEFECTIVE)
NG


7.CHECK ECU AGGREGATION BOX (OPERATION)

  1. Temporarily replace the ECU aggregation box with a new or normally functioning one.

  1. Check if the same DTC is detected.

    OK:
    DTC B1242 is not output.


OK
END (CERTIFICATION ECU IS DEFECTIVE)
NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK (MAIN BODY ECU)