Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 525

13B-44
INSPECTION PROCEDURE 29
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 B-28, B-29.
Disconnect the connectors, and measure at the harness side.
Voltage between 8 and earth, and 45 and earth
(Ignition switch: ON, A/C switch: ON)
OK: System voltage
Short circuit between 8 and earth
(Ignition switch: ON, A/C switch: ON)
OK: A/C compressor clutch turns on.
INSPECTION PROCEDURE 30
Electrical load swich
During idling, the ON/OFF condition of switches is equipment which have a large
electical load is input to the engine-ECU.
The engine-ECU controls the idle speed control servo on this input.
Measure at the engine-ECU connector B-29.
Disconnect the connectors, and measure at the harness side.
Voltage between 41 and earth
(Lighting switch: ON)
OK: System voltage
Check the following connector: B-29
Check the trouble symptoms.
Replace the engine-ECU.
MPI –
OK
OK
OK
NG
Troubleshooting
Probable cause
Malfunction of A/C control system
Malfunction of A/C switch
Improper
short-circuited harness wire
Malfunction of the engine-ECU
NG
Replace
NG
Check the A/C system. (Refer to GROUP 55 – On-vehicle Service.)
OK
Check the following
connectors: B-28, B-29
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Probable cause
Improper
short-circuited harness wire in the headlamp relay
circuit
Improper
short-circuited harness wire in the defogger relay
circuit.
Malfunction of the engine-ECU
NG
Check the headlamp relay circuit.
(Refer to ELECTRICAL WIRING.)
Check the defogger relay circuit.
(Refer to ELECTRICAL WIRING.)
NG
Repair
connector contact, open circuit
NG
Replace
connector contact, open circut
connector contact, open circuit
or
or
or