Check Power Supply And Ground Line Of Engine Control Module (ECM)

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >

WIRING DIAGRAM:

Fig 1: Power Supply And Ground Line Of Engine Control Module (ECM) - Wiring Diagram

DIAGNOSIS PROCEDURE

Step	Check	Yes	No
1 CHECK MAIN RELAY. Turn the ignition switch to OFF. Remove the main relay. Using a lead wire, connect the terminal No. 1 of main relay to positive terminal of battery, and terminal No. 2 to ground terminal of battery. Measure the resistance between main relay terminals. Terminals No. 3 - No. 6: No. 4 - No. 5:	Is the measured value less than 10 Ω?	Go to step 2.	Replace the main relay.
2 CHECK GROUND CIRCUIT OF ECM. Disconnect the connector from ECM. Measure the resistance of harness between ECM and chassis ground. Connector & terminal (B134) No. 5 - Chassis ground: (B136) No. 15 - Chassis ground: (B137) No. 1 - Chassis ground: (B137) No. 2 - Chassis ground: (B137) No. 3 - Chassis ground: (B137) No. 7 - Chassis ground:	Is the measured value less than 5 Ω?	Go to step 3.	Repair the open circuit in harness between ECM connector and engine grounding terminal or poor contact in connector.
3 CHECK INPUT VOLTAGE OF ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B135) No. 5 (+) - Chassis ground (-): (B135) No. 27 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Go to step 4.	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 measured value more than 10 V?	Go to step 5.	Repair the open or ground short circuit in harness of power supply circuit.
5 CHECK INPUT VOLTAGE OF ECM. Connect the main relay connector. Turn the ignition switch to ON. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B135) No. 2 (+) - Chassis ground (-): (B134) No. 7(+) - Chassis ground (-): (B136) No. 24 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Check the ignition control system. < Ref. to IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure. >	Repair the open or ground short circuit in harness between ECM connector and main relay connector.