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.
Checking the contolling state of main relay every 10 sec. under detecting condition, if open or short in the circuit is detected for more than 5 sec., PCM sets P0685.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Detects a short to ground, to battery or open circuit on Main Relay output Fault information provided by an output driver chip. | ● Poor Connection ● Open or short in control circuit. ● Main Relay ● PCM |
Enable Conditions | ● Engine Running ● 11V ≤ Ignition Voltage ≤ 16V ● Enable Time delay ≥ 0.5sec. | |
Threshold value | ● Open or Short | |
Diagnosis Time | ● Contineous (More than 5sec. Failure for every 10 sec. test) | |
MIL On Condition | ● DTC only (NO MIL ON) |
Coil Resistance | 70Ω ~ 120Ω |
