Driver Side ECU Power Source Circuit: Procedure

WARNING: This page is about a different car, the 2011 Lexus IS 350 and 2011 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FRONT POWER SEAT SWITCH LH (POSITION CONTROL ECU POWER SOURCE CIRCUIT)

Disconnect the front power seat switch LH (position control ECU) connectors.

Fig 1: Identifying Front Power Seat Switch LH Connector Terminals
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Measure the voltage according to the value(s) in the table below.

Standard voltage

Tester Connection	Condition	Specified Condition
U6-5 (+B) - Body ground	Always	10 to 14 V
U7-4 (IG) - Body ground	Engine switch on (IG)	10 to 14 V
U7-8 (SYSB) - Body ground	Always	10 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK: Go to next step

INSPECT FRONT POWER SEAT SWITCH LH (POSITION CONTROL ECU GROUND CIRCUIT)

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

Fig 2: Identifying Front Power Seat Switch LH Connector Terminals

Standard resistance

Tester Connection	Condition	Specified Condition
U6-1 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT)

OK → PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE