Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FUSE (MPX-B3)
1. Remove the MPX-B3 fuse from the passenger side junction block.
2. Measure the resistance of the fuse.
  Standard resistance: Below 1 Ω
NG: REPLACE FUSE

OK: Go to next step.

CHECK WIRE HARNESS (DRIVER SIDE JUNCTION BLOCK ECU - BATTERY AND BODY GROUND))

Disconnect the 2G junction block connector.
Disconnect the D4 ECU connector.

Fig 1: Identifying 2G Junction Block Connector And D4 ECU Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the voltage and resistance of the wire harness side connectors.

Standard voltage

VOLTAGE SPECIFICATION

Tester Connection	Specified Condition
D4-5 (MPX-B) - Body ground	10 to 14 V

Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
D4-1 (GND2) - Body ground	Below 1 Ω
2G-8 (GND) - Body ground	Below 1 Ω

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step.

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the D2, D4, T8 and A31 ECU connectors.

Fig 2: Identifying D2, D4, T8 And A31 ECU Connectors
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance of the wire harness side connectors.

Standard resistance

RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
D2-15 (MPX1) - A31 -6 (MPX2)	Below 1 Ω
D4-7 (MPX2) - T8-7 (MPX1)	Below 1 Ω

Result

RESULT CHART

Result	Proceed to
Both are OK	A
One is OK	B
Both are NG	C

B: REPLACE DRIVER SIDE JUNCTION BLOCK AND REPAIR OR REPLACE HARNESS AND CONNECTOR

C: REPAIR OR REPLACE HARNESS AND CONNECTOR

A: REPLACE DRIVER SIDE JUNCTION BLOCK