Power Supply (MFI Relay) and Ignition Switch
Operation
While the ignition switch is ON, battery power supply is supplied to the engine control module, injectors, volume air flow sensor, etc. When the ignition switch is switched ON, current flows from the ignition switch, via the multiport fuel injection relay coil to ground.
As a result, the multiport fuel injection relay switch is switched ON, and power is supplied, by way of the multiport fuel injection relay switch, from the battery to the engine control module.
Inspection
Harness Inspection
Multiport Fuel Injection Relay Inspection
(1) Remove the multiport fuel injection relay.
(2) Use jumper wires and connect multiport fuel injection relay terminal 10 to the battery (+) terminal and terminal 8 to the battery (-) terminal.
Caution: Be very careful when connecting the jumper wires because the relay will be damaged if a mistake is made with the contact terminals.
(3) With battery (-) terminal jumper wire connected and disconnected, measure the Voltage at multiport fuel injection relay terminals 4 and 5.
(4) Use jumper wires to connect multiport fuel injection relay terminal 9 to the battery (+) terminal and terminal 6 to the battery (-)terminal.
(5) Disconnecting the jumper wire on the terminal (-) side of the battery, check whether or not continuity exists across terminals 2 and 3 of the multi port fuel injection relay.
(6) Use jumper wires and connect multiport fuel injection relay terminal 3 to the battery (+) terminal and terminal 7 to the battery (-) terminal.
(7) With the battery (-) terminal jumper wire connected and disconnected, measure the Voltage at multiport fuel injection relay terminal 2.
(8) Replace the multi port fuel injection relay if faulty.
Engine Control Module Power Ground
Operation
Grounding of the engine control module.
Troubleshooting Hints
If there is incorrect or incomplete contact of the engine control module's ground line, the engine control module will not function correctly.
Harness Inspection