Toyota 4Runner: BUS IC Communication Malfunction (B1497/97)

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Automatic Air Conditioning System) / BUS IC Communication Malfunction (B1497/97)

DESCRIPTION

The air conditioning harness assembly connects the No. 1 air conditioning amplifier assembly and each servo motor. The No. 1 air conditioning amplifier assembly supplies power and sends operation instructions to each servo motor through the air conditioning harness assembly. Each servo motor sends the damper position information to the No. 1 air conditioning amplifier assembly.

DTC Code	DTC Detection Condition	Trouble Area
B1497/97	An open circuit or malfunction in the communication line.	Air conditioning harness assembly No. 1 air conditioning amplifier assembly

WIRING DIAGRAM

PROCEDURE

1.	CHECK NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Remove the No. 1 air conditioning amplifier assembly with its connectors still connected (See page ).

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
z15-2 (BUS G) - Body ground	Always	Below 1 Ω

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
z15-2 (BUS G) - z15-4 (B BUS)	Always	11 to 14 V
z15-2 (BUS G) - z15-3 (BUS)	Ignition switch ON	Pulse generation

Text in Illustration

*a	Component with harness connected (No. 1 Air Conditioning Amplifier Assembly)

Result

Result	Proceed to
OK (When troubleshooting according to problem symptoms table)	A
OK (When troubleshooting according to the DTC)	B
NG	C

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE AIR CONDITIONING HARNESS ASSEMBLY

REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

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DESCRIPTION The damper servo sub-assembly (driver side air mix damper servo) sends pulse signals to inform the No. 1 air conditioning amplifier assembly of the damper position. The No. 1 air cond ...

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