Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

When "+B or GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTC B1262, repair the "+B or GND short malfunction of communication bus" DTCs first.

INSPECT FUSE (ECU-B)
1. Remove the ECU-B fuse from the fusible link block.
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)

Fig 1: Identifying A8 ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the A8 ECU connector.

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

Standard voltage

VOLTAGE SPECIFICATION TABLE

Tester Connection	Condition	Specified Condition
+B (A8-2) - Body ground	Always	10 to 14 V

Standard resistance

RESISTANCE SPECIFICATION TABLE

Tester Connection	Specified Condition
GND (A8-6) - Body ground	Below 1 Ω

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

CHECK RESISTANCE OF COMMUNICATION LINE

Fig 2: Identifying A8, A20 & G3 ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the A8, A20 and G3 ECU connectors.

Measure the resistance of the wire harness side connector.

Standard resistance

RESISTANCE SPECIFICATION TABLE

Tester Connection	Specified Condition
MPX+ (A8-3) - MPX2 (A20-22)	Below 1 Ω
MPX- (A8-4) - MPI1 (G3-4)	Below 1 Ω

Result

RESULT TABLE

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

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