Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2012 Lexus LS 460 AWDFACTORY OEM SERVICE PROCEDURE

DTC B1243: GSW Terminal Circuit Malfunction: Procedure

CHECK DTC OUTPUT

Delete the DTC. Refer to DTC CHECK/CLEAR .

Recheck for DTC.

RESULT

Result	Proceed to
B1243 output reoccurs	A
B1243 output does not reoccur	B

B → See step 6

A: Go to next step

CHECK HARNESS AND CONNECTOR (CENTER AIRBAG SENSOR - MAIN BODY ECU)
1. Disconnect the negative (-) terminal cable from the battery.
  WARNING: Wait at least 90 seconds after disconnecting the negative (-) terminal cable from the battery to prevent airbag and seat belt pretensioner activation.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.

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