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Last Modified: 11-27-2007 1.6 C
Service Category: Vehicle Interior Section: Door Lock
Model Year: 2008 Model: LX570 Doc ID: RM000002BX900AX
Title: DOOR LOCK: WIRELESS DOOR LOCK CONTROL SYSTEM: DESCRIPTION (2008 LX570)

DTC

B1242

Wireless Door Lock Tuner Circuit Malfunction

DESCRIPTION

The door control receiver is used to receive electrical waves relating to the entry functions of the smart access system with push-button start (for Entry Function). The certification ECU (smart key ECU assembly) decodes the requested smart access system with push-button start (for Entry Function) operation by identifying a key code based on the electric waves received via the door control receiver. The door control receiver receives a signal from the door control transmitter and sends signals to the main body ECU (cowl side junction block LH) through the certification ECU (smart key ECU assembly). The certification ECU (smart key ECU assembly) then sends a command, according to the requested operation, to each ECU (ex. if door lock operation is requested, the certification ECU (smart key ECU assembly) sends a door lock command to the main body ECU).

This DTC is stored when one of the following occurs: 1) a short in RDA or RSSI to ground between the certification ECU (smart key ECU assembly) and the door control receiver, or 2) a short in RDA or RSSI to ground when RCO (5 V) output from the ECU is off.

NOTICE:

  • When replacing or inspecting the door control receiver and wire harness, do not change the position or length of the wire harness. If the wire harness is too close to the door control receiver, entry and wireless function performance may be affected.
  • Before performing the inspection, check that there are no problems related to the CAN communication system and LIN communication system.
  • When using the Techstream with the engine switch off to troubleshoot: Connect the Techstream to the vehicle, and turn the front door courtesy light switch LH on and off at 1.5 second intervals until communication between the Techstream and vehicle begins.

DTC Code

DTC Detection Condition

Trouble Area

B1242

One of the following conditions is met:

  • Short in RDA or RSSI to ground between the certification ECU (smart key ECU assembly) and the door control receiver.
  • Short in RDA or RSSI to ground when RCO (5 V) output from the ECU is off.
  • Harness or connector
  • Door control receiver
  • Certification ECU (smart key ECU assembly)

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.

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

(a) Disconnect the E29 ECU connector.

(b) Disconnect the L21 receiver connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

E29-39 (RSSI) - L21-2 (RSSI)

Always

Below 1 Ω

E29-38 (RDA) - L21-5 (DATA)

E29-29 (RCO) - L21-4 (+5)

E29-17 (E) - Body ground

L21-1 (GND) - Body ground

E29-39 (RSSI) or L21-2 (RSSI) - Body ground

Always

10 kΩ or higher

E29-38 (RDA) or L21-5 (DATA) - Body ground

E29-29 (RCO) or L21-4 (+5) - Body ground
OK

2.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Disconnect the L21 receiver connector.

(b) Reconnect the E29 ECU connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

L21-4 (+5) - Body ground

Always

4.5 to 5.4 V
OK

3.

REPLACE DOOR CONTROL RECEIVER

(a) Temporarily replace the door control receiver with a new one DOOR LOCK: DOOR CONTROL RECEIVER: REMOVAL (2008 LX570) .

NEXT

4.

CHECK FOR DTC

(a) Clear the DTC DOOR LOCK: WIRELESS DOOR LOCK CONTROL SYSTEM: DTC CHECK / CLEAR (2008 LX570) .

(b) Recheck for DTC DOOR LOCK: WIRELESS DOOR LOCK CONTROL SYSTEM: DTC CHECK / CLEAR (2008 LX570) .

OK:

DTC B1242 is not output.

OK