S10/T10 Blazer 4WD V6-4.3L VIN W (1997)
Compass: Testing and Inspection
Long Distance Travel
Calibration of the compass may become necessary when the vehicle is operated a significant distance from the initial point of compass calibration. This
is due to differences in the magnetic declination, changes in the angle formed between the magnetic needle and geographical meridian across the country
and the coordinate system used by the compass to determine direction (magnetic North). The customer may suspect a problem when indeed the compass
system is operating normally.
An approximate 15 degree deviation (declination) from true North occurs between the East and West coasts as a result of the earth's curvature. These
deviations throughout the country are due to differences in the magnetic fields.