MPI <4G9> -
Troubleshooting
13A-150
INSPECTION PROCEDURE 28
Ignition switch-ST system
Probable cause
The ignition switch-ST outputs a HIGH signal to the engine-ECU <M/T> or
engine-A/T-ECU <A/T> while the engine is cranking.
The engine-ECU <M/T> or engine-A/T-ECU <A/T> uses this signal to carry out
functions such as fuel injection control during starting.
D
Malfunction of the ignition switch
D
Malfunction of the inhibitor switch <A/T>
D
Open circuit or short-circuited harness wire of the
ignition switch circuit
D
Malfunction of the engine-ECU <M/T>
D
Malfunction of the engine-A/T-ECU <A/T>
<M/T>
NG
Replace the engine-ECU.
OK
Check the trouble symptoms.
OK
Check the following connector:
B-35
NG
Repair
NG
Repair
OK
Check the ignition switch.
(Refer to GROUP 54.)
NG
Check the harness wire between the
engine-ECU and the ignition switch.
OK
Check the trouble symptoms.
NG
Check the following connectors:
B-34, B-35
NG
Repair
Measure at the engine-ECU connector
B-34.
D
Disconnect the connector, and
measure at the harness side.
D
Voltage between 71 and earth
(Ignition switch: START)
OK:
8 V or more
<A/T>
Measure at the inhibitor switch connector A-27.
D
Disconnect the connector, and measure at the harness
side.
D
Voltage between 10 and earth (Ignition switch: START)
OK:
System voltage
NG
Replace the engine-A/T-ECU.
OK
Check the trouble symptoms.
NG
Repair
OK
Check the following connector:
A-27
NG
Check the harness wire between inhibitor switch and engine-A/T-
ECU, and repair if necessary.
NG
Repair
OK
Check the trouble symptoms.
NG
Check the following connectors:
A-27, B-94
OK
Measure at the engine-A/T-ECU connector B-94.
D
Disconnect the connector, and measure at the harness
side.
D
Voltage between 58 and earth
(Selector lever position: P or N)
(Ignition switch: START)
OK:
System voltage
NG
Repair
OK
Check the ignition switch (Refer to GROUP 54 – Ignition Switch.)
NG
Check the harness wire between inhibitor switch and ignition switch.
NG
Repair
OK
Check the trouble symptoms.
NG
Check the following connector:
B-33
OK
Check the inhibitor switch
D
Continuity between 9 and 10
(Refer to GROUP 23 – On-vehicle service.)
NG
Replace