2004 CADILLAC DEVILLE service

Headlamp Aiming
Your vehicle has a visual optical headlamp aiming system
which may be equipped with horizontal aim indicators.
The aim has been preset at the factory and should need
no further adjustment. This is true even though your
horizontal aim indicators (if equipped) may not fall exactly
on the “0” (zero) marks on their scales.
If your vehicle is damaged in an accident, the headlamp
aim may be affected. Aim adjustment to the low beam
may be necessary if it is difficult to see lane markers (for
horizontal aim), or if oncoming drivers ash their high
beams at you (for vertical aim). If you believe your
headlamps need to be re-aimed, we recommend that
you take your vehicle to your dealer for service.
However, it is possible for you to re-aim your headlamps
as described in the following procedure.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.
The vehicle should be properly prepared as follows:
The vehicle should be placed so the headlamps are
25 ft. (7.6 m) from a light colored wall or other at
surface.
The vehicle must have all four tires on a perfectly
level surface which is level all the way to the wall
or other at surface.
The vehicle should be placed so it is perpendicular
to the wall or other at surface.
The vehicle should not have any snow, ice or mud
attached to it.
The vehicle should be fully assembled and all other
work stopped while headlamp aiming is being done.
The vehicle should be normally loaded with a
full tank of fuel and one person or 160 lbs. (75 kg)
on the driver’s seat.
Tires should be properly inated.
5-55

Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service,
see your GM Warranty booklet for details. For additional
information refer to the tire manufacturer’s booklet
included with your vehicle’s Owner’s Manual.
{CAUTION:
Poorly maintained and improperly used
tires are dangerous.
Overloading your tires can cause
overheating as a result of too much
friction. You could have an air-out and a
serious accident. SeeLoading Your
Vehicle on page 4-35.
Underinated tires pose the same danger
as overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.
CAUTION: (Continued)
CAUTION: (Continued)

Overinated tires are more likely to be
cut, punctured or broken by a sudden
impact— such as when you hit a pothole.
Keep tires at the recommended pressure.
Worn, old tires can cause accidents. If
your tread is badly worn, or if your tires
have been damaged, replace them.
SeeInflation - Tire Pressure on page 5-74, for
ination pressure adjustment for higher speed
driving.
Tire Sidewall Labeling
Useful information about a tire is molded into its
sidewall. The examples below show a typical passenger
car tire and a compact spare tire sidewall.
5-66

(A) Tire Size:The tire size code is a combination of
letters and numbers used to dene a particular
tire’s width, height, aspect ratio, construction type and
service description. See the “Tire Size” illustration
later in this section for more detail.
(B) Tire Performance Criteria Specication (TPC
Spec):Original equipment tires designed to GM’s
specic tire performance criteria have a TPC specication
code molded onto the sidewall. GM’s TPC specications
meet or exceed all federal safety guidelines.
(C) Department of Transportation (DOT):The
Department of Transportation (DOT) code indicates that
the tire is in compliance with the U.S. Department of
Transportation Motor Vehicle Safety Standards.
(D) Tire Identication Number (TIN):The letters and
numbers following DOT code are the Tire Identication
Number (TIN). The TIN shows the manufacturer and
plant code, tire size, and date the tire was manufactured.
The TIN is molded onto both sides of the tire, although
only one side may have the date of manufacture.
Passenger Car Tire Example
5-67

(A) Temporary Use Only:The compact spare tire or
temporary use tire has a tread life of approximately
3,000 miles (5 000 km) and should not be driven
at speeds over 65 mph (105 km/h). The compact spare
tire is for emergency use when a regular road tire
has lost air and gone at. SeeCompact Spare Tire on
page 5-96andIf a Tire Goes Flat on page 5-85.
(B) Tire Ply Material:The type of cord and number of
plies in the sidewall and under the tread.
(C) Tire Identication Number (TIN):The Tire
Identication Number (TIN). The TIN shows the
manufacturer and plant code, tire size, and date the tire
was manufactured. The TIN is molded onto both
sides of the tire, although only one side may have the
date of manufacture.
(D) Maximum Cold Ination Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. SeeCompact Spare Tire
on page 5-96andLoading Your Vehicle on page 4-35.(E) Tire Ination:The temporary use tire or compact
spare tire should be inated to 60 psi (420 kPa).
For more information on tire pressure and ination see
Ination - Tire Pressure on page 5-74.
(F) Tire Size:A combination of letters and numbers
dene a tire’s width, height, aspect ratio, construction
type and service description. The letter “T” as the
rst character in the tire size means the tire is for
temporary use only.
(G) Tire Performance Criteria Specication (TPC
Spec):Original equipment tires designed to GM’s
specic tire performance criteria have a TPC specication
code molded onto the sidewall. GM’s TPC specications
meet or exceed all federal safety guidelines.
5-69

Tire Size
The following illustration shows an example of a typical
passenger car tire size.
(A) P-Metric Tire:The United States version of a
metric tire sizing system. The letter “P” as the
rst character in the tire size means a passenger
vehicle tire engineered to standards set by the U. S.
Tire and Rim Association.
(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.(C) Aspect Ratio:A two-digit number that indicates the
tire height-to-width measurements. For example, if
the tire size aspect ratio is “70,” as shown in item “C” of
the illustration, it would mean that the tire’s sidewall
is 70% as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire.
The letter “R” means radial ply construction; the letter
“D” means diagonal or bias ply construction; and
the letter “B” means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:These characters represent
the load range and the speed rating of a tire. The load
range represents the load carrying capacity a tire is
certied to carry. The load index can range from 1 to 279.
The speed rating is the maximum speed a tire is certied
to carry a load. Speed ratings range from “A” to “Z”.
5-70

Tire Pressure Monitor Operation
The Tire Pressure Monitor (TPM) system uses radio
and sensor technology to check tire pressure levels.
Sensors, mounted on each road wheel, transmit
tire pressure readings to a receiver located in the trunk.
Tire pressure status and tire pressure warnings are
shown on the Driver Information Center (DIC) display.
SeeDriver Information Center (DIC) on page 3-62,
for details regarding DIC controls and displays.
The system operates on a radio frequency subject to
Federal Communications Commission (FCC) Rules and
with Industry and Science Canada.
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions: (1)
this device may not cause harmful interference, and (2)
this device must accept any interference received,
including interference that may cause undesired
operation.This device complies with RSS-210 of Industry and
Science Canada. Operation is subject to the following
two conditions: (1) this device may not cause
interference, and (2) this device must accept any
interference received, including interference that may
cause undesired operation of the device.
Changes or modications to this system by anyone
other than an authorized service facility could void
authorization to use this equipment.
If the TPM system detects low tire pressure, below
25 psi (172 kPa), or high tire pressure, above 38 psi
(262 kPa), a message, CHECK TIRE PRESSURE, will
appear on the Driver Information Center (DIC)
display. By pressing the INFO button, the DIC screen
will show which tire(s) has the low or high pressure
condition. SeeInation - Tire Pressure on page 5-74for
information regarding correct tire ination. If a tire is
low, you should stop as soon as possible and check all
your tires for damage. If a tire is at, seeIf a Tire
Goes Flat on page 5-85.
5-76

Notice:Do not use a tire sealant if your vehicle is
equipped with Tire Pressure Monitors. The liquid
sealant can damage the tire pressure monitor
sensors.
Once a low or high tire pressure condition is detected,
the TPM system will display the CHECK TIRE
MESSAGE each time the engine is started, until the
tire(s) are set to the correct ination pressure.
The Tire-Loading Information Label, which is located on
the rear edge of the driver’s door, shows the correct
ination pressure for the tires on your vehicle.
The TPM system also allows the driver to check the air
pressure status of each road tire using the Driver
Information Center (DIC). Each tire’s air pressure will be
listed individually, in the following order: LF (left front
or driver’s side front tire), RF (right front or passenger’s
side front tire), RR (right rear or passenger’s side
rear tire) and LR (left rear or driver’s side rear tire). See
Ination - Tire Pressure on page 5-74for information
regarding correct tire ination. Also, seeDriver
Information Center (DIC) on page 3-62for information
on the DIC controls and displays.If the DIC display does not show tire pressures or the
SERVICE TPM SYSTEM message appears, see
your dealer for service. The TPM system may not work
properly while the compact spare tire is installed.
Anytime you replace one or more tires or rotate your
tires, the TPM system will need to be reset. A special
tool is needed to reset the sensor identication
codes. See your dealer for service.
Your vehicle was delivered from the factory with
aluminum valve stem caps. If you ever have to replace
the valve stem caps on your vehicle, you should
replace them with aluminum or plastic caps.
The TPM system can alert you about a low or high tire
pressure condition, but it does not replace normal
tire maintenance. SeeTires on page 5-66.
5-77

Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-79andWheel Replacement
on page 5-82for more information.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The rst rotation
is the most important. SeeScheduled Maintenance
on page 6-4.When rotating your tires, always use the correct rotation
pattern shown here.
Don’t include the compact spare tire in your tire rotation.
After the tires have been rotated, adjust the front and
rear ination pressures as shown on the Tire and
Loading Information label.
Vehicles equipped with the Tire Pressure Monitor (TPM)
system will need to have the sensors reset after a tire
rotation is performed. A special tool is needed to
reset the sensor identication codes. See your dealer
for service.
Make certain that all wheel nuts are properly tightened.
See “Wheel Nut Torque” underCapacities and
Specications on page 5-115.
5-78