Mitsubishi Lancer Evolution VI - Page 155

MPI – Troubleshooting
13-44
INSPECTION PROCEDURE 32
Ignition circuit system
Probable cause
The engine-ECU interrupts the ignition coil primary current by turning the power transistor
inside the engine-ECU ON and OFF.
D Malfunction of ignition switch.
D Improper connector contact, open or short-circuited
harness wire
D Malfunction of the engine-ECU
Measure at the ignition coil connectors A-110, A-111.
D Disconnect the connector and measure at the harness side.
1. Voltage between 1 and earth (Ignition switch: ON)
OK: System voltage
2. Continuity between 2 and earth
OK: Continuity
1. NG
Check the following
connectors: B-65, B-76
NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between ignition coil and
ignition switch connector.
NG
Repair
OK
Check the ignition switch.
2. NG
Check the harness wire between ignition coil connector and earth,
and repair if necessary.
OK
Check the following
connectors:
A-110, A-111
NG
Repair
OK
Check trouble symptom.
NG
Check ignition coil and power transistor unit system. (Refer to
P.13-16, INSPECTION PROCEDURE FOR DIAGNOSIS CODE
44.)
INSPECTION PROCEDURE 33
Idle speed control (ISC) servo (Stepper motor) system
Probable cause
The engine-ECU controls the intake air volume during idling by opening and closing
the servo valve located in the bypass air passage.
D Malfunction of ISC servo
D Improper connector contact, open or short-circuited
harness wire
D Malfunction of the engine-ECU
Check the ISC servo.
NG
Replace
OK
Measure at the ISC servo connector A-18.
D Disconnect the connector and measure at the harness side.
D Voltage between 2 and earth, and 5 and earth (Ignition switch:
ON)
OK: System voltage
NG
Check the harness wire between control relay and ISC servo con-
nector, and repair if necessary.
OK
Measure at the engine-ECU connector B-59.
D Disconnect the connector, measure at the harness side.
D Voltage between each of 4, 5, 17, 18 and earth (Ignition switch:
ON)
OK: System voltage
NG
Check the following
connector: A-18
NG
Repair
OK
Check trouble symptom.
NG
Check harness wire between engine-ECU and ISC servo connector,
and repair if necessary.
OK
Check the following
connector: B-59
NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.