ENGINE (DIAGNOSTICS)(H4DOTC) > Diagnostics for Engine Starting Failure > CHECK POWER SUPPLY AND GROUND LINE OF ENGINE CONTROL MODULE (ECM)

ENGINE (DIAGNOSTICS)(H4DOTC) > Diagnostics for Engine Starting Failure

CHECK POWER SUPPLY AND GROUND LINE OF ENGINE CONTROL MODULE (ECM)

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

• LHD model

• RHD model

STEP	CHECK	YES	NO
1.CHECK MAIN RELAY. 1) Turn the ignition switch to OFF. 2) Remove the main relay. 3) Connect the battery to main relay terminals No. 1 and No. 2. 4) Measure the resistance between main relay terminals. Terminals No. 3 — No. 5: No. 4 — No. 6:	Is the resistance less than 10 Ω?		Replace the main relay.
2.CHECK GROUND CIRCUIT FOR ECM. 1) Disconnect the connectors from the ECM. 2) Measure the resistance of harness between ECM and chassis ground. Connector & terminal (B134) No. 5 — Chassis ground: (B137) No. 1 — Chassis ground: (B137) No. 2 — Chassis ground: (B137) No. 3 — Chassis ground: (B137) No. 7 — Chassis ground: MT model (B136) No. 15 — Chassis ground:	Is the resistance less than 5 Ω?		Repair the open circuit of harness between ECM connector and engine grounding terminal.
3.CHECK INPUT VOLTAGE OF ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B135) No. 5 (+) — Chassis ground (−): (B135) No. 19 (+) — Chassis ground (−):	Is the voltage 10 V or more?		Repair the open or ground short circuit of power supply circuit.
4.CHECK INPUT VOLTAGE OF MAIN RELAY. Measure the voltage between main relay connector and chassis ground. Connector & terminal (B47) No. 1 (+) — Chassis ground (−): (B47) No. 5 (+) — Chassis ground (−): (B47) No. 6 (+) — Chassis ground (−):	Is the voltage 10 V or more?		Repair the open or ground short circuit of harness of power supply circuit.
5.CHECK INPUT VOLTAGE OF ECM. 1) Connect the main relay connector. 2) Turn the ignition switch to ON. 3) Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 7 (+) — Chassis ground (−): (B135) No. 2 (+) — Chassis ground (−): (B136) No. 23 (+) — Chassis ground (−):	Is the voltage 10 V or more?	Check ignition control system.	Repair the open or ground short circuit of harness between ECM connector and main relay connector.