Inspection Procedure

WARNING: This page is about a different car, the 2006 Lexus IS 350 and 2006 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FUSE (MPX-B)
1. Remove the MPX-B from the engine room J/B No. 1.
2. Measure the resistance of the fuse.
  Standard resistance:
  
  Below 1 Ω
NG: REPLACE FUSE

OK: Go to next step.

CHECK WIRE HARNESS (MAIN BODY ECU LH - BATTERY AND BODY GROUND)

Disconnect the LD ECU connector.

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

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION TABLE

Tester Connection	Condition	Specified Condition
MPX-B (LD-18) - Body ground	Always	10 to 14 V

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION TABLE

Tester Connection	Specified Condition
GND (LD-3) - Body ground	Below 1 ohms

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 1: Identifying Main Body ECU LH Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to next step.

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the Q3, A30, M7 and 2F ECU connectors.

Measure the resistance between the specified terminals on the wire harness side connectors.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION TABLE

Tester Connection	Specified Condition
MPX1 (Q3-15) - MPX1 (M7-7)	Below 1 ohms
MPX2 (A30-17) - 2F-6	Below 1 ohms

Result

RESULT DESCRIPTION TABLE

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

B: REPAIR OR REPLACE HARNESS OR CONNECTOR AND REPLACE MAIN BODY ECU LH

C: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 2: Identifying Main Body ECU LH Connector Terminals

A: REPLACE MAIN BODY ECU LH