Mark VII V8-302 50L VIN F Compass System Diagnostic Procedure
Vehicle Demagnetizing
If the compass is inaccurate after calibration, the vehicle's residual magnetism may be too high and vehicle demagnetizing is necessary. Initially the
vehicle's roof is demagnetized to a sufficient magnetic level by the manufacturer. In most cases this is all that is needed during the life of the vehicle.
However, if after calibration the compass still is inaccurate, demagnetizing must be performed.
The demagnetizing process requires the use of a demagnetizing coil commonly used by television service technicians to demagnetize television tubes.
Demagnetize the vehicle by sweeping across the roof area over the compass with a demagnetizing coil as follows:
NOTE:
The demagnetizing procedure must be performed exactly as described. Never turn demagnetizing equipment on or off within three feet of a
vehicle's roof or the vehicle may be remagnetized.
1.
Standing three or more feet away from vehicle, turn on demagnetizing coil.
NOTE:
Whenever the demagnetizing equipment is being operated over the vehicle's roof or within 91 mm (3 feet) of the vehicle,
the operator must maintain a constant steady motion. Failure to do so may result in the vehicle being remagnetized.
2.
In one continuous motion make four passes over roof of vehicle. The demagnetizer should be held 25 mm (1 inch) or less (but not
touching) away from roof surface.
3.
After four passes and without stopping motion of demagnetizing coil, pull demagnetizer away from vehicle.
4.
When demagnetizer is at least 91 mm (3 feet) away from vehicle, turn it off.
5.
Perform the compass calibration procedure as outlined in Adjustments.
Diagnosis
