One terminal of main relay is connected to battery and the other terminal which is ground point is conneted to PCM. PCM monitors the voltages flowing into main relay and going through it.
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 |