1A-170 Engine General Information and Diagnosis:
4 Wire harness check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “C37-43” terminal of ECM
connector and engine ground.
Is resistance infinity?
Go to Step 5. “RED” wire is shorted to
other circuit.
5 Wire harness check
1) Measure voltage between “C37-43” terminal of ECM
connector and engine ground with ignition switch turned
ON.
Is voltage 0 V?
Substitute a known-
good ECM and recheck.
“RED” wire is shorted to
other circuit.
6 Wire harness check
1) Measure voltage between “GRN” wire terminal of electric
throttle body connector and engine ground, between
“WHT” wire terminal of electric throttle body connector
and engine ground with ignition switch turned ON.
Is each voltage 4 – 6 V?
Go to Step 9. Go to Step 7.
7 Wire harness check
1) Turn OFF ignition switch.
2) Disconnect connectors from ECM.
3) Check for proper connection of ECM connector at “C37-
54” and “C37-40” terminals.
4) If OK, measure voltage between “C37-54” terminal of
ECM connector and engine ground, between “C37-40”
terminal of ECM connector and engine ground.
Is each voltage 0 V?
Go to Step 8. “GRN” wire or “WHT”
wire is shorted to other
circuit.
8 Wire harness check
1) Measure resistance between “GRN” wire terminal of
electric throttle body connector and engine ground,
between “WHT” wire terminal of electric throttle body
connector and engine ground with ignition switch turned
OFF.
Is each resistance infinity?
Substitute a known-
good ECM and recheck.
“GRN” wire or “WHT”
wire is shorted to other
circuit.
9 Electric throttle body check
1) Check TP sensor referring to “Throttle Position Sensor
Performance Check” under “Electric Throttle Body
Assembly On-Vehicle Inspection in Section 1C”.
Is each output voltage within specified value?
Substitute a known-
good ECM and recheck.
Replace electric throttle
body.
Step Action Yes No
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