F 550 4WD Super Duty V8-6.4L DSL Turbo (2008)
B5-B7
Test C: The Compass Is Inaccurate
PINPOINT TEST C: THE COMPASS IS INACCURATE
Normal Operation
The compass sensor module or interior rear view mirror communicates the vehicle direction to the instrument cluster (IC) through the compass
communication data plus circuit VMC31 (YE/GN) and compass communication data minus circuit VMC30 (BU/GY). The magnetic fields generated
by the earths north and south poles are divided into zones that differ from each other with respect to how the magnetic fields appear. The magnetic
north can change by up to 4 degrees between zones and become noticeable across multiple zones. The compass zone must be set to the correct zone
for the compass to read accurately. Factors within the vehicle may affect the ability of the compass module to accurately read the magnetic north.
Calibrating the compass allows the compass module to compensate for vehicle factors that influence the accuracy of the compass.
NOTE: Outside factors such as bridges, steel structures, tall buildings and power lines also affect compass accuracy.
This pinpoint test is intended to diagnose the following:
