Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DTC OUTPUT
1. Clear the DTC (See DTC CHECK / CLEAR ).
2. Check for DTC.
  OK: B1243 output does not reoccur.
NG: Go to step 2

OK: USE SIMULATION METHOD TO CHECK (See HOW TO PROCEED WITH TROUBLESHOOTING )

CHECK HARNESS AND CONNECTOR (CENTER AIRBAG SENSOR - MAIN BODY ECU RH)

Disconnect the cable from the negative (-) battery terminal
CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Disconnect the center airbag sensor assembly connector
Disconnect the main body ECU RH (cowl side junction block RH) connector

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Condition	Specified Condition
J47-18 (GSW) - RA-7 (GSW)	Always	Below 1 Ω
RA-7 (GSW) - Body ground	Always	10 kΩ or higher

Fig 1: Identifying RA And J47 Connectors Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) (GSW VOLTAGE)

Disconnect the cable from the negative (-) battery terminal
CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Reconnect the main body ECU RH (cowl side junction block RH) connector
Connect the cable to the negative (-) battery terminal

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

Standard Voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Condition	Specified Condition
J47-18 (GSW) - Body ground	Engine switch on (IG)	4 5 to 5.5 V

NOTE: Turning the engine switch on (IG) with the center air bag sensor assembly connector disconnected causes other DTC s to be stored. Clear the DTC s after performing this inspection.

Fig 2: Identifying J47 Connector Terminals

NG: REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH)

OK: Go to next step

REPLACE CENTER AIRBAG SENSOR ASSEMBLY
1. Disconnect the cable from the negative (-) battery terminal
  CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
2. Replace the center airbag sensor assembly (See REMOVAL )
CHECK DTC OUTPUT
1. Recheck for DTC (See DTC CHECK / CLEAR )
  OK: B1243 output does not reoccur.
NG: REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH)

OK: END (CENTER AIR BAG SENSOR ASSEMBLY IS DEFECTIVE)