A/C relay which is controled by ECM supplies and cut electrical power to A/C compressor. ECM activates or deactivates A/C relay based on inputted signal such as A/C switch siganl and A/C pressure switch signal. As controlling A/C relay, ECM 1)turns OFF A/C compressor at rapid acceleration to retain suffiecient capacity for acceleration, 2)actively performs idle-up function to cope with the change of engine load which happens at A/C compressor operation.
P0646 is set when ‘0A’ is detected in A/C relay control circuit for more than 1 sec.. This code is due to open or short to ground in A/C relay control circuit or internal open in relay component.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Voltage monitoring | ● A/C relay circuit ● A/C relay component | ||
Enable Conditions | ● IG KEY "ON" | |||
Threshold Value | ● Short to GND ● Wiring open | |||
Diagnostic Time | ● 1.0 sec. | |||
Fail Safe | Fuel Cut | NO | ||
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | OFF | |||
