Mitsubishi FUEL Manual page 174

13A-174
INSPECTION PROCEDURE 30
A/C switch and A/C relay system
When an A/C ON signal is input to the engine-ECU, the engine-ECU carries out
control of the idle speed control (ISC) servo, and also operates the A/C compressor
magnetic clutch.
Check the A/C compressor relay.
(Refer to GROUP 55 - On-vehicle Service.)
Measure at the engine-ECU connectors C-166, C-168.
D Disconnect the connector, and measure at the harness side.
D Voltage between 20 and earth, and 83 and earth
(Ignition switch: ON)
OK: 0 - 3 V (A/C switch: OFF)
System voltage (A/C switch: ON)
D Short circuit between 20 and earth
(Ignition switch: ON, A/C switch: ON)
OK: A/C compressor clutch turns on.
INSPECTION PROCEDURE 31
Ignition circuit system
The engine-ECU interrupts the ignition coil primary current by turning the ignition
power transistor inside the engine-ECU ON and OFF.
MPI <6A1> -
OK
Troubleshooting
Probable cause
D Malfunction of A/C control system
D Malfunction of A/C switch
D Improper
short-circuited harness wire
D Malfunction of the engine-ECU
NG
Replace
NG
Check the A/C system. (Refer to GROUP 55 - Troubleshooting.)
OK
Check the following
connectors:
C-166, C-168
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Probable cause
D Malfunction of ignition coil
D Malfunction of power transistor unit
D Improper
short-circuited harness wire
D Malfunction of the engine-ECU
connector contact, open circuit
NG
Replace
connector contact, open circuit
or
or