The PCM provides ground to one side of the coil of the main relay and the other side is connected to the battery. The PCM monitors battery voltage and the voltage after the main relay.
The PCM 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 PCM 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
? Comparison of battery voltage and voltage after main relay
? Open or short circuit
? Contact resistance in connectors
Case 1)
Enable Conditions
? Battery voltage >10V
? Ignition ON
Threshold Value
? Voltage after main relay when ON < 6V
Diagnosis Time
? 180 mSec.
Case 2)
? Ignition OFF
? Voltage after main relay when ON > 6V