DTC B1262: A/C ECU Communication Stop: Procedure

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

CHECK HARNESS AND CONNECTOR (A/C ECU - BATTERY AND BODY GROUND)

Disconnect the D37 ECU connector.

Measure the voltage according to the value(s) in the table below.

Voltage

Tester Connection	Condition	Specified Condition
D37-21 (IG+) - Body ground	Ignition switch off → on (IG)	0 V → 10 to 14 V
D37-1 (B) - Body ground	Always	10 to 14 V

Measure the resistance according to the value(s) in the table below.

Resistance

Tester Connection	Condition	Specified Condition
D37-20 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the D37, E23, and D44^*1 or D13^*2 ECU connectors.

Measure the resistance according to the value(s) in the table below.

Resistance

Tester Connection	Condition	Specified Condition
D37-30 (MPX+) - D44-24 (MPX2) ^*1	Always	Below 1 Ω
D37-30 (MPX+) - D13-7 (MPX2) ^*2		Below 1 Ω
D37-31 (MPX-) - E23-3 (MPD1)		Below 1 Ω

HINT:

^*1 : w/ Smart key system

^*2 : w/o Smart key system

Result

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

B → REPLACE A/C ECU AND REPAIR OR REPLACE HARNESS OR CONNECTOR

C → REPAIR OR REPLACE HARNESS OR CONNECTOR

A → REPLACE A/C ECU