DTC B1262 A/C ECU Communication Stop

DESCRIPTION

This DTC is detected when communication between the air conditioning amplifier (A/C ECU) and gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1262	Air conditioning amplifier (A/C ECU) communication stops	Air conditioning amplifier (A/C ECU) Wire harness

Dtc B1262 A/C Ecu Communication Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

When "+B of 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.

1.CHECK FUSE (A/C)

Remove the A/C fuse from the main body ECU LH (cowl side J/B LH).

Measure the resistance of the fuse.

REPLACE FUSE

OK

2.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 Condition Specified Condition
B (J58-1) - Body ground Always 10 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.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 Specified Condition
^*1MPX- (J58-31) - MPX1 (A27-5) Below 1 Ω
^*2MPX- (J58-31) - MPX+ (J34-6) Below 1 Ω
MPX+ (J58-30) - MPI2 (J76-13) Below 1 Ω

*1: w/ Adaptive front-lighting system

*2: w/o Adaptive front-lighting system

REPLACE AIR CONDITIONING AMPLIFIER AND REPAIR OR REPLACE HARNESS OR CONNECTOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

Tester Connection	Condition	Specified Condition
B (J58-1) - Body ground	Always	10 to 14 V

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