Main relay operates when Ignition ON signal is inputted to terminal 58 of ECM C113-1 connector and it supplies power to ECM, fuel pump relay, CMP, EGR actuator, throttle flap actuator, supplementary heater relay and brake switch, etc. Especially, the power supplied to ECM is used as main power of injectors, rail pressure regulator and ECM operation.
Even at engine turned OFF, when Ignition OFF signal is inputted to terminal 58 of ECM C113-1 connector, engine turns OFF as cutting fuel injection from injector. all the systems are shut dowm after 5 min.
Main relay is very important for engine operation, so careful inspection is strongly required.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Voltage monitoring | ● Main relay circuit ● Main relay component | ||
Enable Conditions | ● Ignition "ON" | |||
Threshold Value | ● When main relay respond to Ignition - ON/OFF signal too fast | |||
Diagnostic Time | ● Immediately | |||
Fail Safe | Fuel Cut | NO | ||
EGR Off | NO | |||
Fuel Limit | NO | |||
MIL | YES |