Lexus IS250 IS220d GSE20 ALE20 - DOOR LOCK
CHECK HARNESS AND CONNECTOR (CENTER AIRBAG SENSOR - MAIN BODY ECU RH)
INSPECT COWL SIDE JUNCTION BLOCK RH (MAIN BODY ECU RH)
DTC B1243 GSW Terminal Circuit Malfunction
DESCRIPTION
If the collision door lock release function does not operate normally, or an open or short in the GWS input circuit of the main body ECU RH (cowl side J/B RH) is detected, DTC B1243 will be output.
- HINT:
- If DTC B1243 is output, the speed-sensitive automatic door lock function, shift-linked automatic door unlock function, and collision door lock release function will be prohibited.
DTC No. | DTC Detection Condition | Trouble Area |
B1243 | A malfunction occurs in the GWS input circuit of the main body ECU RH (cowl side J/B RH). | Main body ECU RH (Cowl side J/B RH) Center airbag sensor Wire harness |
WIRING DIAGRAM
INSPECTION PROCEDURE
1.CHECK HARNESS AND CONNECTOR (CENTER AIRBAG SENSOR - MAIN BODY ECU RH) |

Connect the negative (-) terminal cable to the battery, and wait for at least 90 seconds.
Disconnect the center airbag sensor J47 and J/B RA connectors.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection
(Symbols)Condition Specified Condition J47-18 (GSW) - RA-7 (GSW) Always Below 1 Ω RA-7 (GSW) - Body ground Always 10 kΩ or higher
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OK | |
2.INSPECT COWL SIDE JUNCTION BLOCK RH (MAIN BODY ECU RH) |

Reconnect the J/B RA connector.
Turn the engine switch on (IG).
Measure the voltage according to the value(s) in the table below.
- Standard voltage:
Tester Connection
(Symbols)Condition Specified Condition RA-7 (GSW) - Body ground Engine switch on (IG) 4.5 to 5.5 V
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OK | ||
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