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
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.
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.
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. | Door Control Receiver
Wire harness
Certification ECU
|
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - DOOR CONTROL RECEIVER) |
Disconnect the P33 certification ECU connector and P31 door control receiver connector.
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 |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 2.INSPECT CERTIFICATION ECU |
Reconnect the P33 ECU connector.
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 |
| | REPLACE CERTIFICATION ECU |
|
|
| 3.REPLACE DOOR CONTROL RECEIVER |
Replace the door control receiver with normal one
Perform the registration procedure.
- OK:
- The system returns to normal operation.
| | REPLACE CERTIFICATION ECU |
|
|
LEXUS IS250, IS220d / GSE20 ALE20
