ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)
DTC DETECTING CONDITION:
Depending on the content of malfunction, adapt either of the followings.
• Immediately at fault recognition
• Detected when two consecutive driving cycles with fault occur.
TROUBLE SYMPTOM:
• Improper idling
• Poor driving performance
CAUTION:
After repairing or replacing the defective part, perform the Clear Memory Mode 
and Inspection Mode .
WIRING DIAGRAM:
1.CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and chassis ground.
Connector & terminal
(B136) No. 3 (+) — Chassis ground (−):
(B136) No. 4 (+) — Chassis ground (−):
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Is the voltage 10 — 13 V?
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Repair the open or ground short circuit of power supply circuit.
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2.CHECK INPUT VOLTAGE OF ECM.
2) Measure the voltage between ECM and chassis ground.
Connector & terminal
(B136) No. 3 (+) — Chassis ground (−):
(B136) No. 4 (+) — Chassis ground (−):
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Is the voltage 13 — 15 V?
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Repair the open or ground short circuit of power supply circuit.
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3.CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and electronic throttle control.
3) Measure the resistance of harness between ECM and electronic throttle control connector.
Connector & terminal
(B134) No. 28 — (E57) No. 6:
(B134) No. 29 — (E57) No. 3:
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Is the resistance less than 1 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following item:
• Open circuit in harness between ECM and electronic throttle control connector
• Poor contact of coupling connector
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4.CHECK ECM GROUND HARNESS.
Measure the voltage between ECM and chassis ground.
Connector & terminal
(B135) No. 3 (+) — Chassis ground (−):
(B135) No. 4 (+) — Chassis ground (−):
(B135) No. 5 (+) — Chassis ground (−):
(B136) No. 6 (+) — Chassis ground (−):
(B137) No. 1 (+) — Chassis ground (−):
(B137) No. 6 (+) — Chassis ground (−):
(B137) No. 7 (+) — Chassis ground (−):
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Is the voltage less than 1 V?
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Repair the poor contact of the ECM connector.
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Repair the following item.
• Further tightening of the engine ground terminal
• Poor contact in ECM connector
• Poor contact of coupling connector
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