service CADILLAC DTS PROFESSIONAL 2007 1.G Repair Manual

Gasoline Octane
Use premium unleaded gasoline with a posted
octane rating of 91 or higher. You can also use
regular unleaded gasoline rated at 87 octane or
higher, but your vehicle’s acceleration could be
slightly reduced, and you might notice a slight
audible knocking noise, commonly referred to as
spark knock. If the octane is less than 87, you might
notice a heavy knocking noise when you drive. If
this occurs, use a gasoline rated at 87 octane or
higher as soon as possible. Otherwise, you could
damage the engine. If you are using gasoline rated
at 87 octane or higher and you hear heavy
knocking, the engine needs service.
Gasoline Specications
At a minimum, gasoline should meet ASTM
specication D 4814 in the United States or
CAN/CGSB-3.5 in Canada. Some gasolines may
contain an octane-enhancing additive called
methylcyclopentadienyl manganese tricarbonyl
(MMT). General Motors recommends against the
use of gasolines containing MMT. SeeAdditives
on page 357for additional information.
California Fuel
If your vehicle is certied to meet California
Emissions Standards, it is designed to operate on
fuels that meet California specications. See
the underhood emission control label. If this fuel is
not available in states adopting California
emissions standards, your vehicle will operate
satisfactorily on fuels meeting federal
specications, but emission control system
performance may be affected. The malfunction
indicator lamp may turn on and your vehicle may
fail a smog-check test. SeeMalfunction Indicator
Lamp on page 234. If this occurs, return to
your authorized GM dealer for diagnosis. If it is
determined that the condition is caused by the type
of fuel used, repairs may not be covered by
your warranty.
356

Additives
To provide cleaner air, all gasolines in the United
States are now required to contain additives
that will help prevent engine and fuel system
deposits from forming, allowing your emission
control system to work properly. In most cases,
you should not have to add anything to your fuel.
However, some gasolines contain only the
minimum amount of additive required to meet U.S.
Environmental Protection Agency regulations.
To help keep fuel injectors and intake valves clean,
or if your vehicle experiences problems due to
dirty injectors or valves, look for gasoline that is
advertised as TOP TIER Detergent Gasoline. Also,
your dealer has additives that will help correct
and prevent most deposit-related problems.
Gasolines containing oxygenates, such as
ethers and ethanol, and reformulated gasolines
may be available in your area. General Motors
recommends that you use these gasolines if they
comply with the specications described earlier.However, E85 (85% ethanol) and other fuels
containing more than 10% ethanol must not be
used in vehicles that were not designed for
those fuels.
Notice:Your vehicle was not designed for
fuel that contains methanol. Do not use
fuel containing methanol. It can corrode metal
parts in the fuel system and also damage
plastic and rubber parts. That damage would
not be covered under your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant where you
buy gasoline whether the fuel contains MMT.
General Motors recommends against the use of
such gasolines. Fuels containing MMT can reduce
the life of spark plugs and the performance of
the emission control system may be affected. The
malfunction indicator lamp may turn on. If this
occurs, return to your dealer for service.
357

How to Reset the Engine Oil
Life System
The Engine Oil Life System calculates when to
change the engine oil and lter based on vehicle
use. Whenever the oil is changed, reset the
system so it can calculate when the next oil
change is required. If a situation occurs where you
change the oil prior to a CHANGE ENGINE OIL
SOON message in the Driver Information
Center (DIC) being turned on, reset the system.
After the oil has been changed, the CHANGE
ENGINE OIL SOON message must be reset:
1. Turn the key to the RUN position without
starting the engine.
2. Press the INFO button on the Driver
Information Center (DIC) until OIL LIFE
REMAINING is displayed. SeeDIC Controls
and Displays on page 240.
3. Press and hold the INFO RESET button until
100% is displayed. This resets the oil life
indicator.
4. Turn the key to OFF.If the CHANGE ENGINE OIL SOON message
comes back on when you start your vehicle, the
engine oil life system has not reset. Repeat
the procedure.
What to Do with Used Oil
Used engine oil contains certain elements that can
be unhealthy for your skin and could even cause
cancer. Do not let used oil stay on your skin for very
long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly
dispose of clothing or rags containing used engine
oil. See the manufacturer’s warnings about the use
and disposal of oil products.
Used oil can be a threat to the environment. If you
change your own oil, be sure to drain all the oil
from the lter before disposal. Never dispose of oil
by putting it in the trash, pouring it on the
ground, into sewers, or into streams or bodies of
water. Instead, recycle it by taking it to a place
that collects used oil. If you have a problem
properly disposing of used oil, ask your
dealer/retailer, a service station, or a local
recycling center for help.
369

Automatic Transaxle Fluid
When to Check and Change Automatic
Transaxle Fluid
A good time to check your automatic transaxle
uid level is when the engine oil is changed.
Change the uid and lter at the intervals listed in
Additional Required Services on page 468, and
be sure to use the transaxle uid listed in
Recommended Fluids and Lubricants on page 475.
How to Check Automatic
Transaxle Fluid
Because this operation can be a little difficult, you
may choose to have this done at the dealership
service department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading
on the dipstick.Notice:Too much or too little uid can damage
the transaxle. Too much can mean that some of
the uid could come out and fall on hot engine
or exhaust system parts, starting a re. Too
little uid could cause the transaxle to overheat.
Be sure to get an accurate reading if you check
the transaxle uid.
Wait at least 30 minutes before checking the
transaxle uid level if you have been driving:
When outside temperatures are above
90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
To get the right reading, the uid should be at
normal operating temperature, which is 180°F to
200°F (82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are
above 50°F (10°C). If it is colder than 50°F (10°C),
you may have to drive longer.
372

Notice:Using coolant other than DEX-COOL®
may cause premature engine, heater core,
or radiator corrosion. In addition, the engine
coolant may require changing sooner, at the rst
maintenance service after each 30,000 miles
(50 000 km) or 24 months, whichever occurs
rst. Any repairs would not be covered by your
warranty. Always use DEX-COOL
®(silicate-free)
coolant in your vehicle.
What to Use
Use a mixture of one-half clean, drinkable water
and one-half DEX-COOL®coolant which will
not damage aluminum parts. If you use this coolant
mixture, you do not need to add anything else.
{CAUTION:
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can
boil before the proper coolant mixture will.
Your vehicle’s coolant warning system is
set for the proper coolant mixture.
CAUTION: (Continued)
CAUTION: (Continued)
With plain water or the wrong mixture, your
engine could get too hot but you would not
get the overheat warning. Your engine
could catch re and you or others could be
burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
Notice:If you use an improper coolant
mixture, your engine could overheat and be
badly damaged. The repair cost would not be
covered by your warranty. Too much water
in the mixture can freeze and crack the engine,
radiator, heater core, and other parts.
If you have to add coolant more than two times a
year, have your dealer check your cooling system.
Notice:If you use extra inhibitors and/or
additives in your vehicle’s cooling system, you
could damage your vehicle. Use only the
proper mixture of the engine coolant listed in
this manual for the cooling system. See
Recommended Fluids and Lubricants on
page 475for more information.
375

If you get the overheat warning with no sign of
steam, try this for a minute or so:
1. In heavy traffic, let the engine idle in
NEUTRAL (N) while stopped. If it safe to do
so, pull off the road, shift to PARK (P) or
NEUTRAL (N) and let the engine idle.
2. Set the climate controls to the highest heat
setting and fan speed and open the windows
as necessary.
If you no longer have the overheat warning, you
can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not come
back on, you can drive normally.
If the warning continues, pull over, stop, and park
your vehicle right away.
If there is still no sign of steam, idle the engine for
three minutes while you are parked. If you still
have the warning, turn off the engine and
get everyone out of the vehicle until it cools down.
Also, see “Overheated Engine Protection
Operating Mode” later in this section.
You may decide not to lift the hood but to get
service help right away.Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
message ENGINE OVERHEATED STOP ENGINE
is displayed, an overheat protection mode which
alternates ring groups of cylinders helps
prevent engine damage. In this mode, you will
notice a loss in power and engine performance.
This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in
the overheat protection mode should be avoided.
Notice:After driving in the overheated
engine protection operating mode, to avoid
engine damage, allow the engine to cool before
attempting any repair. The engine oil will be
severely degraded. Repair the cause of coolant
loss, change the oil and reset the oil life
system. SeeEngine Oil on page 365.
379

{CAUTION:
An electric engine cooling fan under the
hood can start up even when the engine
is not running and can injure you. Keep
hands, clothing, and tools away from any
underhood electric fan.
If the coolant inside the coolant surge tank is
boiling, do not do anything else until it cools down.
The vehicle should be parked on a level surface.
{CAUTION:
Heater and radiator hoses, and other
engine parts, can be very hot. Do not
touch them. If you do, you can be burned.
Do not run the engine if there is a leak. If
you run the engine, it could lose all
coolant. That could cause an engine re,
and you could be burned. Get any leak
xed before you drive the vehicle.If there seems to be no leak, with the engine on,
check to see if the electric engine cooling fans
are running. If the engine is overheating, both fans
should be running. If they are not, your vehicle
needs service.
Notice:Engine damage from running your
engine without coolant is not covered by your
warranty. SeeOverheated Engine Protection
Operating Mode on page 379for information on
driving to a safe place in an emergency.
Notice:Using coolant other than DEX-COOL
®
may cause premature engine, heater core, or
radiator corrosion. In addition, the engine
coolant could require changing sooner, at
30,000 miles (50 000 km) or 24 months,
whichever occurs rst. Any repairs would not
be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your
vehicle.
381

Brakes
Brake Fluid
The brake master
cylinder reservoir is
lled with DOT-3 brake
uid. SeeEngine
Compartment Overview
on page 364for
reservoir location and
access.
There are only two reasons why the brake uid
level in the reservoir might go down. The rst
is that the brake uid goes down to an acceptable
level during normal brake lining wear. When
new linings are put in, the uid level goes back
up. The other reason is that uid is leaking out of
the brake system. If it is, you should have the
brake system xed, since a leak means that
sooner or later the brakes will not work well.So, it is not a good idea to top off the brake uid.
Adding brake uid will not correct a leak. If
you add uid when the linings are worn, then you
will have too much uid when you get new
brake linings. You should add or remove brake
uid, as necessary, only when work is done on the
brake hydraulic system.
{CAUTION:
If your vehicle has too much brake uid, it
can spill on the engine. The uid will burn if
the engine is hot enough. You or others
could be burned, and your vehicle could be
damaged. Add brake uid only when work
is done on the brake hydraulic system.
If the ignition is on and the brake uid is low, the
SERVICE BRAKE SYSTEM message will be
displayed in the Driver Information Center (DIC).
SeeDIC Warnings and Messages on page 246.
387

{CAUTION:
The brake wear warning sound means that
soon the brakes will not work well. That
could lead to an accident. When you hear
the brake wear warning sound, have your
vehicle serviced.
Notice:Continuing to drive with worn-out
brake pads could result in costly brake repair.
Some driving conditions or climates can cause
a brake squeal when the brakes are rst applied or
lightly applied. This does not mean something is
wrong with the brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated,
inspect brake pads for wear and evenly tighten
wheel nuts in the proper sequence to torque
specications inCapacities and Specications on
page 460.
Brake linings should always be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does
not return to normal height, or if there is a
rapid increase in pedal travel. This could be a sign
that brake service might be required.
Brake Adjustment
Every time you apply the brakes, with or without
the vehicle moving, the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its
many parts have to be of top quality and work well
together if the vehicle is to have really good
braking. Your vehicle was designed and tested with
top-quality brake parts. When you replace parts of
the braking system — for example, when the brake
linings wear down and you need new ones put
in — be sure you get new approved replacement
parts. If you do not, the brakes might not work
properly. For example, if someone puts in brake
linings that are wrong for your vehicle, the
balance between the front and rear brakes can
change — for the worse. The braking performance
you have come to expect can change in many other
ways if someone puts in the wrong replacement
brake parts.
389

9. Connect the other end of the negative (−)
cable to the negative (−) terminal location
on the vehicle with the dead battery.
Your vehicle has a remote negative (−)
terminal marked GND (−).
10. Now start the vehicle with the good battery
and run the engine for a while.
11. Try to start the vehicle that had the dead
battery. If it will not start after a few tries, it
probably needs service.
Notice:If the jumper cables are connected or
removed in the wrong order, electrical
shorting may occur and damage the vehicle.
The repairs would not be covered by your
warranty. Always connect and remove
the jumper cables in the correct order, making
sure that the cables do not touch each other
or other metal.A. Heavy, Unpainted Metal Engine Part or
Remote Negative (−) Terminal (GND)
B. Good Battery or Remote Positive (+) and
Remote Negative (−) Terminals
C. Dead Battery or Remote Positive (+) Terminal
To disconnect the jumper cables from both
vehicles, do the following:
1. Disconnect the black negative (−) cable from
the vehicle that had the dead battery.
2. Disconnect the black negative (−) cable from
the vehicle with the good battery.
Jumper Cable Removal
396