The ECM provides ground to one side of the coil of the main relay and the other side is connected to the battery. The ECM monitors battery voltage and the voltage after the main relay.
The ECM measures the voltage from ignition key and from main relay respectively and compares two voltages. This comparison will watch if the Main Relay has switched and remains on after ignition Key-On and if it has switched off after the ignition Key-Off. The ECM sets DTC P0560 if the voltage after Main Relay is lower than a predetermined threshold after ignition key-on or higher than a predetermined threshold after ignition key-off.
Item
Detecting Condition
Possible Cause
DTC
Strategy
Case1
Comparison of battery voltage and voltage after main relay(Voltage low)
Open or short circuit
Poor connection or damaged harness
Case2
Comparison of battery voltage and voltage after main relay(Voltage high)
Case3
Monitor voltage supply after main relay(open circuit check)
Enable
Conditions
Ignition "ON"
Battery voltage > 10V
Delay time after main relay ON > 0.05sec.
Ignition "OFF"
Voltage after main relay > 8.5V
Voltage after ignition switch > 5V
Threshold
Value
Voltage after Main Relay < 6 V
Voltage after Main Relay >6 V
Voltage after main relay - Voltage after ignition switch > 3.8~8.5V
Diagnostic
Time
0.2 sec.
0.1 sec.
MIL On Condition
-