The ECM controls cooling fan speed (low,medium, high) based on engine coolant temperature, vehicle speed, and A/C switch position. Fans will default to high-speed operation upon ECT or VSS failure.
ECM sets DTC P1624 if the ECM detects that the fan relay control line is open, short to ground or battery.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Driver stage check | ● Contact resistance in connectors ● Open or short circuit ● Malfunctioning fan relay |
Enable Conditions | ● Battery voltage > 10V | |
Threshold Value | ● Open or short to ground ● Short to battery | |
Diagnostic Time | ● 10 seconds |