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.

2008 Lexus LS 460FACTORY OEM SERVICE PROCEDURE

Inspection Procedure

CHECK TCM (POWER SOURCE, BODY GROUND)

Disconnect the A12 and E5 TCM connectors.
Turn the engine switch on (IG).

Measure the voltage of the wire harness side connectors.

Standard Voltage

VOLTAGE SPECIFICATION

Tester Connection	Switch Condition	Specified Condition
A12-6 (+B) - E5-7 (E1)	Engine switch on (IG)	11 to 14 V

Turn the engine switch off.

Measure the resistance of the wire harness side connector.

Standard Resistance

RESISTANCE REFERENCE

Tester Connection	Condition	Specified Condition
ES-7 (E1) - Body ground	Always	Below 1 Ω

Fig 1: Identifying A12 And E5 TCM Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: CHECK HARNESS AND CONNECTOR (TCM EFI MAIN NO. 2 RELAY, BODY GROUND)

OK: GO TO ECM POWER SOURCE CIRCUIT (ENGINE CONTROL SYSTEM / SFI SYSTEM) (See ECM POWER SOURCE CIRCUIT )

Factory Service Tools

Use the Manual With the Right Hardware

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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.