ECU Power Source Circuit [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU AND RECEIVER - AUXILIARY BATTERY AND BODY GROUND)

Disconnect the P29 or P25 tire pressure warning ECU and receiver connector.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Standard Voltage

FOR FMVSS138 TYPE

Tester Connection	Condition	Specified Condition
P29-1 (IG) - Body ground	Power switch on (IG)	10 to 16 V
P29-1 (IG) - Body ground	Power switch off	Below 1 V

FOR ECE-R64 TYPE

Tester Connection	Condition	Specified Condition
P25-1 (IG) - Body ground	Power switch on (IG)	10 to 16 V
P25-1 (IG) - Body ground	Power switch off	Below 1 V

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

Standard Resistance

FOR FMVSS138 TYPE

Tester Connection	Condition	Specified Condition
P29-12 (GND) - Body ground	Always	Below 1 Ω

FOR ECE-R64 TYPE

Tester Connection	Condition	Specified Condition
P25-12 (GND) - Body ground	Always	Below 1 Ω

TEXT IN ILLUSTRATION

*A	for FMVSS138 Type
*B	for ECE-R64 Type
*a	Front view of wire harness connector (to Tire Pressure Warning ECU and Receiver)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK → See step 2

REPLACE TIRE PRESSURE WARNING ECU AND RECEIVER. Refer to REMOVAL [08/2013 - ]