Cadillac 1998 Seville Owner's Manual page 312

Headlamp Aiming
Your vehicle has the composite headlamp system.
These headlamps have horizontal and vertical aim
indicators. The aim has been pre-set at the factory
and should need no further adjustment.
If your vehicle is damaged in an accident and the
headlamp aim seems to be affected, see your dealer.
Headlamps on damaged vehicles may require
recalibration of the horizontal aim by your dealer.
To check the aim, the vehicle should be properly
prepared as follows:
Place the vehicle on a level pad or surface.
The vehicle should not have any snow, ice or mud
attached to it.
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The vehicle should be fully assembled and all other
work stopped while headlamp aiming is being done.
There should not be any cargo or loading of the
vehicle, except it should have a full tank of fuel and
one person or 160 lbs. (75 kg) on the driver's seat.
Tires should be properly inflated.
Rock the vehicle to stabilize the suspension.
NOTICE:
To make sure your headlamps are aimed
properly, read all the instructions before
beginning. Failure to follow these instructions
could cause damage to headlamp parts.