P1601

Diagram Chart:

CIRCUIT DESCRIPTION

Extremely high temperatures can affect the ECM, thus reducing reliability. The ECM is enclosed within the relay center in the engine compartment. A small fan that is located in the left front fender directs fresh air through the relay center in order to reduce the temperature of the ECM. This fan is not ECM controlled and is designed in order to operate in conjunction with the engine coolant fans. An inoperative fan, or an obstructed air flow may allow the ECM to overheat. If the ECM detects that the ECM is getting too hot, this DTC will set.


CONDITIONS FOR RUNNING THE DTC

Tested continuously


CONDITIONS FOR SETTING THE DTC

The ECM temperature is greater than 105°C (221°F)

OR

The internal temperature sensor value is out of range [below -50°C (-58°F) or above 140°C (284°F)]

ACTION TAKEN WHEN THE DTC SETS

The ECM will not illuminate the Malfunction Indicator Lamp (MIL).


CONDITIONS FOR CLEARING THE MIL/DTC

^ The DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other non-emission related diagnostic.

^ The ECM battery voltage is interrupted.

^ The scan tool clears the MIL/DTC.


TEST DESCRIPTION

The number(s) below refer to the step numbers on the diagnostic table.

2. Since there is no ECM based functional check for this fan, proceed to Electrical Diagnosis, Coolant Fans after completing the preliminary checks in this table. If the fan is operational, and no other trouble was found, the ECM may be at fault, however, this is an unlikely failure.