MPI <4G9> -
Troubleshooting
13A-145
INSPECTION PROCEDURE 23
Idling speed is improper when A/C is operating
Probable cause
If the engine-ECU <M/T> or engine-A/T-ECU <A/T> detects that the air
conditioner is on, it activates the idle speed control (ISC) servo to control idle-up
operation.
The A/C-ECU judges if the load caused by air conditioner operation is high or
low, and converts it to voltage signal (high or low voltage) and inputs the signal
to the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
Based on this voltage signal, the engine-ECU <M/T> or engine-A/T-ECU <A/T>
controls the idle-up speed (for high or low load).
D
Malfunction of the A/C control system
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU <M/T> or
engine-A/T-ECU <A/T>
NG
Repair
NG
Replace the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
NG
Check the A/C system. (Refer to GROUP 55 - On-vehicle Service.)
OK
Check the trouble symptom.
Measure at the engine-ECU connector B-37 <M/T> or the engine-
A/T-ECU connector B-95 <A/T>
D
Connect the connector.
D
Voltage between 8 <Vehicles with immobilizer system for
M/T>, 22 <Vehicles without immobilizer system for M/T>,
21 <Vehicles with immobilizer system for A/T>, 20
<Vehicles without immobilizer system for A/T> and earth
(Engine: at idle, outside air temperature: 25
_
C or more)
OK:
0 - 3 V [When A/C is MAX. COOL condition (when
the load by A/C is high)]
System voltage [When A/C is MAX. HOT condition
(when the load by A/C is low)]
OK
Check the following connector:
B-37 <M/T>, B-95 <A/T>
