B441 Part 1 of 2

Chart:

Schematic:

DESCRIPTION
Code B441 is set by the Body Control Module (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:
- 12 Volts if the fans have been turned off.
- O Volts if the fans have been turned on.
- 12 Volts if the fans have been turned on and an excessive current draw exists (stalled or shorted fan motors).
- O Volts if both fan connectors are open.

The BCM will set Code B441 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 B441 current 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 during the next ignition cycle to determine 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 conditions will result in the "Coolant Temp/Fan" display on the Climate Control Driver Information Center (CCDIC) being illuminated whenever the control temperatures require cooling fans operation.

1. The cooling fans override feature (BS04) can be used to evaluate the system,, operation. If higher 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 feedback input B141 can be used to evaluate the feedback signal being received by the BCM. If the input does not agree with the actual fans operation, circuit 791 must be investigated for a possible malfunction. If the input does agree with the commanded fans operation within the appropriate time period, then the cause of Code B441 is not currently present.


NOTE ON INTERMITTENTS


If an intermittent Code B441 is being set, manipulate the related wiring while observing the cooling fans feedback B141 and commanding "High Fans" or "Fans Off" in the override diagnostic mode. If the failure is induced, the fans status will not agree with the commanded operation. This will help in isolating the location of the malfunction.