Ford Transit 2002 Owner's Manual page 56

Check any non-factory installed accessories for being the source of the
1
noise. For example: touch condition body-to-frame, antennas, deflectors
and fog lights.
Are the accessories the cause of the noise?
Yes
ADJUST, REPAIR, or INSTALL new accessories or fasteners as required.
ROAD TEST as necessary.
No
VERIFY the customer concern.
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