ignition CHEVROLET ASTRO 2005 Service Manual

Tow/Haul Mode
Tow/haul is designed to assist while your vehicle is
pulling a large or heavy load or trailer. Tow/haul is most
useful while pulling such a load in rolling terrain, in
stop-and-go traffic, or when you need improved
low-speed control, such as when parking. The purpose
of the tow/haul mode is to:
Reduce the frequency and improve the predictability
of transmission shifts,
provide the same solid shift feel when pulling a
heavy load as when the vehicle is unloaded, and
improve control of vehicle speed while requiring
less throttle pedal activity.
Press the button on the end of the shift lever to turn
tow/haul mode on and off. While activated, the indicator
light on the instrument panel will be on. Tow/haul
mode will turn off automatically when the ignition is
turned off. SeeTow/Haul Mode Light on page 3-35.Tow/haul is most effective when the vehicle and trailer
combined weight is at least 75 percent of the vehicle’s
Gross Combined Weight Rating (GCWR). See “Weight
of the Trailer” later in this section.
Driving with tow/haul activated without a heavy load will
cause reduced fuel economy and unpleasant engine
and transmission driving characteristics, but will
not cause damage.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull
a trailer are all important. And, it can also depend
on any special equipment that you have on your vehicle.
The following chart shows how much your trailer can
weigh, based upon your vehicle model and options.
4-36

Notice:If you leave your radio or other accessories
on during the jump starting procedure, they could
be damaged. The repairs would not be covered
by your warranty. Always turn off your radio and
other accessories when jump starting your vehicle.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off all
lamps that are not needed. This will avoid sparks
and help save both batteries. And it could save the
radio!
4. Open the hoods and locate the batteries. Find the
positive (+) and negative (−) terminals on each
battery.
{CAUTION:
Using a match near a battery can cause battery
gas to explode. People have been hurt doing
this, and some have been blinded. Use a
ashlight if you need more light.
Be sure the battery has enough water. You do
not need to add water to the battery installed
in your new vehicle. But if a battery has ller
caps, be sure the right amount of uid is there.
If it is low, add water to take care of that rst.
If you do not, explosive gas could be present.
Battery uid contains acid that can burn you.
Do not get it on you. If you accidentally get it
in your eyes or on your skin, ush the place
with water and get medical help immediately.
5-44

Fuse/Circuit
BreakerUsage
UPFITTER-
BATTUptter Battery Power Stud,
Trailer Wiring Harness
UPFITTER-
ACCYUptter Accessory Relay
SPARE Spare
SPARE Spare
Fuse/Circuit
BreakerUsage
SPARE Spare
ECM-1BFuel Pump Relay and Motor,
VCM, Oil Pressure Switch/Sender
HORN Horn Relay and Horn
A/C COMPAir Conditioning Enable Relay
and Compressor
RR HTR/AC Rear Heater and Air Conditioning
ATC Active Transfer Case-L Van
FRT HVAC Front Heater and Air Conditioning
ENG-IOxygen Sensors, Camshaft Position
Sensor, Mass Air Flow Sensor,
Evaporative Emission Canister
Vent Solenoid
IGN-E Air Conditioning Enable Relay Coil
ECM-IFuel Injectors 1–6, Crankshaft
Position Sensot, VCM, Coil Driver
Module (EST), Ignition Coil
BLANK Not Used
RH HDLMP Right Headlamp
LH HEADLAMP Left Headlamp
5-99

Fuse/Circuit
BreakerUsage
BLANK Not Used
BLANK Not Used
DIODE-1 Air Conditioning
BLANK Not Used
BLANK Not Used
BLANK Not Used
LIGHTINGCourtesy Fuse, Power Adjust
Mirrors Fuse, Truck Body Control
Battery Fuse
BATTPower Accessory Circuit Breaker,
Stop/Hazard Fuse, Auxiliary Power
Fuse, Cigarette Lighter Fuse,
Radio Battery Fuse
IGN A Starter Relay, Ignition Switch
IGN B Ignition Switch
ABSElectronic Brake
Control Module
BLANK Not Used
RAP Radio Accessory, Power Windows
HTD MIR/RR
DEFOGRear Window Defogger,
Climate Control HeadRelays Usage
A/C RELAY Rear/Heat and Air Conditioning
UPFITTER-
ACCY RELAYUptter Accessory
STARTER
ENABLE
RELAYStarter
A/C ENABLE
RELAYAir Conditioning
HEAD LAMPS
RELAYHeadlamps
FUEL PUMP
RELAYFuel Pump
Feed Usage
AUX B Uptter Battery Feed
AUX A Uptter Accessory Feed
5-100

Starter Switch Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular
brake. SeeParking Brake on page 2-23if
necessary.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately if it starts.
3. Try to start the engine in each gear. The starter
should work only in PARK (P) or NEUTRAL (N).
If the starter works in any other position, your
vehicle needs service.
Automatic Transmission Shift Lock
Control System Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle. It should be parked on a level
surface.
2. Firmly apply the parking brake. SeeParking Brake
on page 2-23if necessary.
Be ready to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the ignition to RUN, but do
not start the engine. Without applying the regular
brake, try to move the shift lever out of PARK (P)
with normal effort. If the shift lever moves out
of PARK (P), your vehicle needs service.
6-26

Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition to LOCK in each shift lever position.
The ignition should turn to LOCK only when the
shift lever is in PARK (P).
The key should come out only in LOCK.
Parking Brake and Automatic
Transmission Park (P) Mechanism
Check
{CAUTION:
When you are doing this check, your vehicle
could begin to move. You or others could be
injured and property could be damaged. Make
sure there is room in front of your vehicle in
case it begins to roll. Be ready to apply the
regular brake at once should the vehicle begin
to move.Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.
To check the parking brake’s holding ability: With
the engine running and transmission in
NEUTRAL (N), slowly remove foot pressure from
the regular brake pedal. Do this until the vehicle is
held by the parking brake only.
To check the PARK (P) mechanism’s holding ability:
With the engine running, shift to PARK (P). Then
release the parking brake followed by the regular
brake.
Underbody Flushing Service
At least every spring, use plain water to ush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other
debris can collect.
6-27

H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-6
Headlamp Wiring............................................5-94
Headlamps
Automatic Headlamp System.........................3-16
Bulb Replacement.......................................5-50
Daytime Running Lamps...............................3-15
Flash-to-Pass............................................... 3-8
Front Turn Signal and Parking Lamps.............5-54
Halogen Bulbs............................................5-50
Headlamps and Sidemarker Lamps................5-50
High/Low Beam Changer................................ 3-8
On Reminder..............................................3-14
Headlamps and Sidemarker Lamps...................5-50
Heater...........................................................3-19
Highbeam On Light.........................................3-34
Highway Hypnosis...........................................4-21
Hill and Mountain Roads..................................4-21
HomeLink
®Transmitter....................................2-29
HomeLink®Transmitter, Programming................2-30
Hood
Checking Things Under................................5-10
Release.....................................................5-11
Horn............................................................... 3-6
How to Use This Manual...................................... ii
How to Wear Safety Belts Properly...................1-23
I
Ignition Positions.............................................2-17
Infants and Young Children, Restraints...............1-40
Ination -- Tire Pressure..................................5-64
Inspection
Brake System.............................................6-29
Engine Cooling System................................6-28
Exhaust System..........................................6-28
Fuel System...............................................6-28
Part C - Periodic Maintenance.......................6-28
Steering, Suspension and Front Drive
Axle Boot and Seal..................................6-28
Throttle System...........................................6-29
Transfer Case and Front Axle
(All-Wheel Drive)......................................6-29
Instrument Panel
Brightness..................................................3-16
Cluster.......................................................3-24
Overview..................................................... 3-4
J
Jump Starting.................................................5-42
6