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
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.
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. | Electrical Key Antenna
Door Control Receiver
Wire harness
Certification ECU
|
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - DOOR CONTROL RECEIVER) |
Disconnect the P33 ECU connector.
Disconnect the P31 receiver connector.
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 |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 2.CHECK HARNESS AND CONNECTOR (DOOR CONTROL RECEIVER - ELECTRICAL KEY ANTENNA) |
Disconnect the P20 antenna connector.
Measure the resistance according to the value(s) in the table below.
- 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 |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 3.CHECK AND REPLACE DOOR CONTROL RECEIVER (RECONFIRM DTC) |
Clear the DTC and repeat the procedure to re-check for DTCs .
| | END (RECEIVER IS DEFECTIVE) |
|
|
| 4.CHECK AND REPLACE ELECTRICAL KEY ANTENNA (RECONFIRM DTC) |
Clear the DTC and repeat the procedure to re-check for DTCs .
| | END (ANTENNA IS DEFECTIVE) |
|
|
| 5.INSPECT CERTIFICATION ECU |
Reconnect the P33 ECU connector.
Reconnect the P20 antenna connector.
Reconnect the P31 receiver connector.
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 |
| | REPLACE CERTIFICATION ECU |
|
|
| OK | |
| |
| PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE |
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LEXUS IS250, IS220d / GSE20 ALE20
