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.

CHECK FUSE (A/C)
1. Remove the A/C fuse from the cowl side J/B LH.
2. Measure the resistance of the fuse.
  Standard resistance: Below 1 Ω
NG: REPLACE FUSE

OK: Go to next step.

CHECK WIRE HARNESS (AIR CONDITIONING AMPLIFIER - BATTERY AND BODY GROUND)

Disconnect the J58 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
B (J58-1) - Body ground	Always	10 to 14 V

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION TABLE

Tester Connection	Specified Condition
GND (J58-20) - Body ground	Below 1 ohms

Fig 1: Identifying A/C ECU Communication Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step.

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the J58, A27, J34 and J76 ECU connectors.

Measure the resistance of the wire harness side connector.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION TABLE

Tester Connection

Specified Condition

MPX- (J58-31) - MPX1 (A27-5)⁽¹⁾

Below 1 ohms

MPX- (J58-31) - MPX+ (J34-6)⁽²⁾

Below 1 ohm

MPX+ (J58-30) - MPI2 (J76-13)

Below 1 ohms

⁽¹⁾	w/Adaptive front-lighting system

⁽²⁾	w/o Adaptive front-lighting system

Result

RESULT DESCRIPTION TABLE

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

Fig 2: Identifying Air Conditioning Amplifier Connector Terminals

B: REPLACE AIR CONDITIONING AMPLIFIER AND REPAIR OR REPLACE HARNESS OR CONNECTOR

C: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY