Mitsubishi FUEL Manual page 168

13A-168
INSPECTION PROCEDURE 23
Low alternator output voltage (approx. 12.3 V)
The alternator may be defective, or malfunctions, which are listed in the right column,
may be suspected.
Measureatthealternatorconnectorside
B-38.
D Connect the connector.
(Test harness: MB991519)
D Voltage between 1 (black clip) and
earth
Engine: At idle
Radiator fan: Does not run
Headlamp: OFF ® ON
Brake lamp: OFF ® ON
Rear defogger switch:
OFF ® ON
OK: Voltages rises
by 0.2 - 3.5 V.
OK
Check the alternator. (Refer to GROUP
16 - Charging System.)
INSPECTION PROCEDURE 24
Idling speed is improper when A/C is operating
If the engine-ECU 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.
Based on this voltage signal, the engine-ECU controls the idle-up speed (for
high or low load).
Measure at the engine-ECU connector C-167.
D Connect the connector.
D Voltage between 65 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)]
Check the A/C system. (Refer to GROUP 55 - On-vehicle Service.)
MPI <6A1> -
NG
Measure at the alternator connector
B-38.
D Disconnect the connector, and
measure at the harness side.
D Disconnect the engine-ECU con-
nector.
D Continuity between 1 and earth
OK: No continuity
Check the following connector:
B-38
Check trouble symptom.
Check the harness wire between the
alternator and the engine-ECU connec-
tor.
Replace the engine-ECU.
NG
Troubleshooting
Probable cause
D Malfunction of charging system
D Short circuit in harness between alternator G terminal
and engine-ECU
D Malfunction of engine-ECU
NG
OK
NG
OK
NG
NG
OK
Probable cause
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
OK
Check the following connector: C-167
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Check the following connectors:
B-31, C-168
OK
NG
Repair
Check trouble symptom.
NG
Repair
Check the harness wire between the
alternator and the engine-ECU connec-
tor, and repair if necessary.
Repair
NG
Repair