
FULL-AUTOMATIC AIR CONDITIONER –
Troubleshooting
55-42
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
Inspection procedure 1
Communication with the MUT-
II
is not possible.
Probable cause
If communication with all other systems is not possible, there is a high
possibility that there is a malfunction of the diagnosis line. If communication
with only the A/C is not possible, the cause is probably a malfunction of the
diagnosis line or of the A/C-ECU power supply system (earth).
D
Malfunction of connector or harness
D
Malfunction of A/C-ECU
Is communication between MUT-
II
and
other system possible?
NO
Check the MUT-
II
diagnosis line, and
repair if necessary.
YES
Measure at the diagnosis connector
B-22.
D
Voltage between terminal (11)
and body earth
OK: Indication fluctuates be-
tween 0 V and 12 V.
OK
Measure at the A/C-ECU connector
B-04.
D
Disconnect the connector, and
measure at the harness side
connector.
D
Voltage between terminal (18)
and body earth
OK: System voltage – 2 V
NG
Check the following connector:
B-04
OK
Check the trouble symptom.
NG
Repair
NG
Measure at the A/C-ECU connector
B-04.
D
Connect the connector.
D
Voltage between terminal (17)
and body earth
OK: Indication fluctuates be-
tween 0 V and 12 V.
NG
OK
Check the following connector:
B-04
NG
Check the harness between the diagno-
sis connector and the A/C-ECU, and
repair if necessary.
NG
Repair
OK
Check the harness between the diagno-
sis connector and the A/C-ECU.
NG
Repair
OK
Check the trouble symptom.
OK
Check the following connectors:
B-04, B-22
NG
Repair
OK
Check the trouble symptom.
NG
Measure at the A/C-ECU connector
B-05.
D
Disconnect the connector, and
measure at the harness side
connector.
D
Voltage between terminal (28)
and body earth
OK: System voltage
NG
Check the following connectors:
B-49, B-75
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the junc-
tion block and the A/C-ECU, and repair
if necessary.
OK
Measure at the A/C-ECU connector
B-05.
D
Disconnect the connector, and
measure at the harness side
connector.
D
Continuity between terminals
(29), (35) and body earth
OK: Continuity
NG
Check the following connectors:
B-05, B-48, B-19, B-67, B-80
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the
A/C-ECU and the body earth, and repair
if necessary.
OK
Replace the A/C-ECU.
NG
Replace the A/C-ECU.