F41

Code F41, Cooling Fans Problem






Important: The following procedure is designed to account for intermittent codes. If no malfunction is uncovered using this procedure, it will indicate that the system is OK at this time. Refer to Note on Intermittents at the end of this test if further investigation is necessary.

Code F41 is set by the BCM if it receives the improper cooling fans feedback voltage. The cooling fans control module is designed to change the feedback voltage on circuit 791 as follows:

- 6-10V if the fans have been turned off.
- 0V if the fans have been turned on.
- 6-10V if the fans have been turned on and an excessive current draw exists (stalled or shorted fan motors)
- 0V if both fan connectors are open.

The BCM will set Code F41 if either of the following conditions exist:

A. The BCM has commanded the fans off but the feedback voltage remains low. The BCM will keep Code F41 hard for the rest of the ignition cycle and continue providing a normal control signal to the cooling fans control module. The BCM will again test this condition if the malfunction has become intermittent.
B. The BCM has commanded the fans on but the feedback voltage remains high. The BCM will command the fans off to protect the system from a possible stalled or shorted motor condition. If the control temperatures (coolant and A/C high side) should drop below the turn off points and later require the fans on, the BCM will repeat the test to determine if the malfunction has become intermittent.

Both of the above will reslut in the "Coolant Temp/Fan" telltale being illuminated whenever the control temperatures require cooling fans operation.

1. The cooling fans override feature (F.8.5) can be used to evaluate the system operation. If either fan is off when "high fans" are commanded or if either fan is on when "fans off" is commanded, the appropriate diagnostic path can be followed to isolate the malfunction.
2. The cooling fans status indicator can be used to evaluate the feedback signal being received by the BCM. If the "auto fan" indicator does not agree with the actual fans operation, circuit 791 must be investigated for a possible malfunction. If the status indicator does agree with the command fans operation within the appropriate time period, then the cause of Code F41 is not currently present.

Notes on Intermittents: If an intermittent Code F41 is being set, manipulate the related wiring while observing the cooling fans status indicator (auto fan) and commanding "High Fans" or "Fans Off" in the F.8.5 diagnostic mode. If the failure is induced, the fans status will not agree with the command operation. This will help in isolating the location of the malfunction.