heating Hyundai Matrix 2003 User Guide

FEATURES OF YOUR HYUNDAI
1- 74
B260D02O-AAT
1. Playing CD
o Insert the CD with the label facing upward.
o Insert the CD to start CD playback, during
radio operation.
o When a disc is in the CD deck, if you press the CD button, the CD player will beginplaying even if the radio is being used.
o The CD player can be used when the igni- tion switch is in either the "ON" or "ACC"position.
2. FF/REW ( / ) If you want to fast forward or reverse through the compact disc track, push and hold in the FF( ) or REW ( ) button.When you release the button, the compact discplayer will resume playing.
3. TRACK UP/DOWN
o The desired track on the disc currently being played can be selected using the track number.
o Press once to skip forward to the beginn- ing of the next track. Press once to skipback to the beginning of the track.
4. SCAN Button
o Press the SCAN button to playback the first 10 seconds of each track.
o Press the SCAN button again within 10 sec. When you have reached the desired track. 5. REPEAT Button
o To repeat the track you are currently listen-
ing to, press the RPT button. To cancel , press again.
o If you do not release RPT operation when the track ends, it will automatically be re-played.This process will be continued until youpush the button again.
6. EJECT Button When the EJECT button is pressed with a CD loaded, the CD will eject. NOTE:
o To assure proper operation of the unit, keep the vehicle interior temperaturewithin a normal range by using thevehicle's air conditioning or heating sys-tem.
o When replacing the fuse, replace it with a fuse having the correct capacity.
o The preset station frequencies are all erased when the car battery is discon-nected. Therefore, all data will have to beset again if this should occur.
o Do not add any oil to the rotating parts. Keep magnets, screwdrivers and othermetallic objects away from the tapemechanism and head.
o This equipment is designed to be used only in a 12 volt DC battery system withnegative ground.
o This unit is made of precision parts. Donot attempt to disassemble or adjust any parts.
o When driving your vehicle, be sure to keep the volume of the unit set low enoughto allow you to hear sounds coming fromthe outside.
o Do not expose this equipment (including the speakers) to water or excessive mois-ture.

FEATURES OF YOUR HYUNDAI 1- 83
H290F01O-GAT
1. CD Select Button
o Insert the CD with the label facing upward.
o Insert the CD to start CD playback, during
radio operation or cassette tape playing.
o When a disc is in the CD deck, if you press the CD button the CD player will beginplaying even if the radio or cassette playeris being used.
o The CD player can be used when the igni- tion switch is in either the "ON" or "ACC"position.
2. FF/REW ( / ) If you want to fast forward or reverse through the compact disc track, push and hold in the FF( ) or REW ( ) button.When you release the button, the compact discplayer will resume playing.
3. TRACK UP/DOWN
o The desired track on the disc currently being played can be selected using the track number.
o Press button once to skip forward to the beginning of the next track. Press buttononce to skip back to the beginning of thetrack. 4. REPEAT
o To repeat the track you are currently listen-
ing to, press the RPT button. To cancel , press again.
o If you do not release RPT operation when the track ends, it will automatically be re-played.This process will be continued until youpush the button again.
5. EQUALIZER Button Press the EQ button to select the CLASSIC, JAZZ, ROCK and DEFEAT MODE for the de-sired tone quality. Each press of the buttonchanges the display as follows; NOTE:
o To assure proper operation of the unit,
keep the vehicle interior temperaturewithin a normal range by using thevehicle's air conditioning or heating sys-tem.
o When replacing the fuse, replace it with a fuse having the correct capacity.
o The preset station frequencies are all erased when the car battery is discon-nected. Therefore, all data will have to beset again if this should occur.
o Do not add any oil to the rotating parts. Keep magnets, screwdrivers and othermetallic objects away from the tapemechanism and head.
o This equipment is designed to be used only in a 12 volt DC battery system withnegative ground.
o This unit is made of precision parts. Do not attempt to disassemble or adjust anyparts.
o When driving your vehicle, be sure to keep the volume of the unit set low enoughto allow you to hear sounds coming fromthe outside.
o Do not expose this equipment (including the speakers and tape) to water or exces-sive moisture.
CLASSIC JAZZ ROCK DEFEAT

6. CD EJECT Button When the button is pressed with a CD loaded, the CD will eject.
7. SCAN Button (If installed)
o Press the SCAN button to playback the first 10 seconds of each track.
o Press the SCAN button again within 10 sec. for the desired track.

DRIVING YOUR HYUNDAI 2- 3
C070C01E
C070C01A-AAT To remove the ignition key
1. Turn the ignition key to the "ACC" position.
2. Simultaneously push and turn the ignition key
counterclockwise from the "ACC" position tothe "LOCK" position.
3. The key can be removed in the "LOCK"
position.LOCK
ACC
ON
START
C050A01E
C050A01A-GAT
STARTING FOR THE GASOLINE ENGINE WARNING: Never run the engine in a closed or poorly ventilated area any longer than is needed to move your car in or out of the area. The carbon monoxide gas emitted is odorless and can cause serious injury or death. C051A01O-GAT STARTING FOR THE DIESEL ENGINE ENGINE COLD
o Turn the ignition key to position "ON" and wait
for the pre-heat indicator light to go out.
o Operate the starter until the engine runs. ENGINE WARM Operate the starter. If the engine does not re- spond on the first attempt, wait several seconds and try again using the pre-heat.
o "LOCK" The key can be removed or inserted in this position. To protect against theft, the steering wheel locks by removing the key. NOTE: To unlocking the steering wheel, insert the key, and then turn the steering wheel and key simultaneously. C050B02S-GAT NORMAL CONDITIONS The Starting Procedure:
1. Insert key, and fasten the seat belt.
2. Depress the clutch pedal fully and place the
gearshift lever (manual transaxle) in neutralor the selector lever (automatic transaxle) in "P" (park) position.
3. After turning the ignition key to the "ON"
position, make certain all warning lights and gauges are functioning properly before start- ing the engine.
4. On vehicles equipped with the diesel preheat
indicator light, turn the ignition key to the "ON" position. The diesel pre-heat indicator light will first illuminate in amber, and then after a short time, the amber illumination will goes off, indicating that preheating is completed.
C050B01HP
Amber lamp ON Amber lamp OFF

DRIVING YOUR HYUNDAI
2- 4 C070A02A-AAT OPERATING THE MANUAL TRANSAXLE
HFC3029
Your Hyundai's manual transaxle has a conven- tional shift pattern. This shift pattern is imprinted on the shift knob. The transaxle is fully synchro- nized in all forward gears so shifting to either a higher or a lower gear is easily accomplished.
C055B01B-GAT STARTING AND STOPPING THE ENGINE FOR TURBO CHARGER INTERCOOLER (DIESEL ENGINE)
(1) Do not race the engine or sudden accelerate
the engine immediately after start it. If the engine is cold, allow the engine to idle for several seconds before it is driven to ensure sufficient lubrication of the turbo charger unit.
(2) After high speed or extended driving, requir- ing a heavy engine load, the engine should be allowed to idle about 1 minute before turning it off.
NOTE: If the engine were not started 10 seconds after the preheating is completed, turn the ignition key once more to the "LOCK" posi- tion, and then to the "ON" position, in order to preheat again. WARNING: Be sure that the clutch is fully depressed when starting a manual transaxle vehicle. Otherwise there is the potential to cause damage to the vehicle or injury to someone inside or outside the vehicle as a result of the forward or backward movement of the vehi- cle that will occur if the clutch is not de- pressed when the vehicle is started.
5. Turn the ignition key to the "Start" position
and release it when the engine starts. This idle time will allow the turbo charger to cool prior to shutting the engine off.
WARNING: Do not turn the engine off immediately after it has been subjected to a heavy load. Doing so may cause severe damage to the engine or turbo charger unit. NOTE:
o To shift into reverse, rest the lever in
neutral for at least 3 seconds after yourcar is completely stopped. Then move the lever into the reverse position.
o During cold weather, shifting may be dif- ficult until the transaxle lubricant has warmed up. This is normal and not harm- ful to the transaxle.
o If you 've come to a complete stop and it's hard to shift into 1 st
or R(Reverse), put the
shift lever in N(Neutral) position and re-lease the clutch. Press the clutch pedal back down, and then shift into 1 st
or
R(Reverse) gear position.
o Do not use the shift lever as a handrest during driving, as this can result in prema-ture wear of the transaxle shift forks.
CAUTION: When downshifting from fifth gear to fourth gear, caution should be taken not to inadvert- ently press the gear shift lever sideways in such a manner that second gear is engaged. Such a drastic downshift may cause the en- gine speed to increase to the point that the tachometer will enter the red zone. Such over-revving of the engine may possibly cause engine damage.

DRIVING YOUR HYUNDAI
2- 8 o Do not hold the vehicle on the upgrade with
the accelerator pedal. This can cause the transmission to overheat. Always use the brake pedal or parking brake.
C120A02A-AAT ANTI-LOCK BRAKE SYSTEM (If Installed) The Anti-Lock Brake System (ABS) is designed to prevent wheel lock-up during sudden braking or on hazardous road surfaces. The ABS control module monitors the wheel speed and controls the pressure applied to each brake. Thus, in emergency situations or on slick roads, ABS will increase vehicle control during braking. NOTE: During ABS operation, a slight pulsation may be felt in the brake pedal when the brakes are applied. Also, a noise may be heard in the engine compartment while braking. These conditions are normal and indicate that the anti-lock brake system is functioning proper- ly. WARNING: ABS will not prevent accidents due to im- proper or dangerous driving maneuvers. Even though vehicle control is improved during emergency braking, always maintain a safe distance between you and objects ahead. Vehicle speeds should always be reduced during extreme road conditions. The braking distance for cars equipped with
also increases the wear of the brake compo-nents.
o If a tire goes flat while you are driving, apply
the brakes gently and keep the car pointed straight ahead while you slow down. When
you are moving slowly enough for it to be safe to do so, pull off the road and stop in a safe place.
o If your car is equipped with an automatic
transaxle, don't let your car creep forward. To avoid creeping forward, keep your foot on the brake pedal when the car is stopped.
o Use caution when parking on a hill. Engage
the parking brake and place the gear selector lever in "P" (automatic transaxle) or in first or
reverse gear (manual transaxle). If your car is
facing downhill, turn the front wheels into the curb to help keep the car from rolling. If your car is facing uphill, turn the front wheels away from the curb to help keep the car from rolling. If there is no curb or if it is required by other conditions to keep the car from rolling, block the wheels.
o Under some conditions your parking brake can freeze in the engaged position. This is most likely to happen when there is an accu- mulation of snow or ice around or near the rear brakes or if the brakes are wet. If there is a risk that the parking brake may freeze, apply it only temporarily while you put the gear selector lever in "P" (automatic) or in first or reverse gear (manual transaxle) and block the rear wheels so the car cannot roll. Then release the parking brake.
C130A01A-AAT GOOD BRAKING PRACTICES WARNING: Nothing should be carried on top of the shelf panel behind the rear seat. If there were an accident or a sudden stop, such objects could move forward and cause damage to the ve- hicle or injure the occupants.
o After being parked, check to be sure the
parking brake is not engaged and that the parking brake indicator light is out before driving away.
o Driving through water may get the brakes
wet. They can also get wet when the car is washed. Wet brakes can be dangerous! Your
car will not stop as quickly if the brakes are wet. Wet brakes may cause the car to pull to one side. To dry the brakes, apply the brakes lightly until the braking action returns to nor-
mal, taking care to keep the car under control at all times. If the braking action does not return to normal, stop as soon as it is safe to do so and call your Hyundai dealer for assis- tance.
o Don't coast down hills with the car out of gear.
This is extremely hazardous. Keep the car in gear at all times, use the brakes to slow down, then shift to a lower gear so that engine braking will help you maintain a safe speed.
o Don't "ride" the brake pedal. Resting your foot on the brake pedal while driving can be dan- gerous because it can result in the brakes overheating and losing their effectiveness. It

DRIVING YOUR HYUNDAI
2- 12 The hitch should be bolted securely to the car and installed by a qualified technician. DO NOT USE A HITCH DESIGNED FOR TEMPORARY INSTALLATION AND NEVER USE ONE THAT ATTACHES ONLY TO THE BUMPER. C190C03S-GAT Trailer Brakes If your trailer is equipped with a braking system, make sure it conforms to federal and/or local regulations and that it is properly installed and operating correctly. NOTE: If you tow a trailer or vehicle, your car will require more frequent maintenance due to the additional load. See "Maintenance Under Severe Usage Conditions" on page 5-5. CAUTION:
o Never connect a trailer brake system di-
rectly to the vehicle brake system.
o When towing a trailer on steep grades (in excess of 12%) pay close attention to theengine coolant temperature gauge to en- sure the engine does not overheat. If the needle of the coolant temperature gauge moves across the dial towards "H" (HOT), pull over and stop as soon as it is safe to do so, and allow the engine to idle until it cools down. You may proceed once the engine has cooled sufficiently.
C180A01A-AAT USE OF LIGHTS Check your lights regularly for correct operation and always keep them clean. When driving dur- ing the day in conditions of poor visibility, it is helpful to drive with headlights on low beam. This enables you to be seen as well as to see. C190A02A-GAT TRAILER OR VEHICLE TOWINGIf you are considering towing with your car, you should first check with your Province Depart- ment of Motor Vehicles to determine their legal requirements. Since laws vary from province to province, the requirements for towing trailers, cars, other types of vehicles, or apparatus may differ. Ask your Hyundai dealer for further details before towing. CAUTION Do not do any towing with your car during its first 2,000 km (1,200 miles) in order to allow the engine to properly break in. Failure to heed this caution may result in serious en- gine or transaxle damage. C190B01S-AAT Trailer Hitches Select the proper hitch and ball combination, making sure that it’s location is compatible with that of the trailer or vehicle being towed. Use a quality non-equalizing hitch which distrib- utes the tongue load uniformly throughout the chassis.
C160K01A-AAT Carry Emergency Equipment Depending on the severity of the weather where you drive your car, you should carry appropriate emergency equipment. Some of the items you may want to carry include tire chains, tow straps or chains, flashlight, emergency flares, sand, a shovel, jumper cables, a window scraper, gloves, ground cloth, coveralls, a blanket, etc. C170A01A-AAT HIGHER SPEED MOTORING Pre-Trip Inspections 1. Tires: Adjust the tire inflation pressures to specifica- tion. Low tire inflation pressures will result in overheating and possible failure of the tires. Avoid using worn or damaged tires which may result in reduced traction or tire failure. NOTE: Never exceed the maximum tire inflation pres- sure shown on the tires. 2. Fuel, engine coolant and engine oil: High speed travel consumes 1.5 times more fuel than urban motoring. Do not forget to check both engine coolant and engine oil. 3. Drive belt: A loose or damaged drive belt may result in overheating of the engine.

DRIVING YOUR HYUNDAI
2- 14 MANUAL
TRANSAXLE AUTO
TRANSAXLE Trailer
1,300
(2,865) 1,100
(2,424)
550 (1,212) Tongue
52
(115)
kg (Lbs.)
Maximum Towable Weight
With BrakeType
1.5 Diesel 1.6/1.8 L 1.6/1.8 L
WARNING: Improperly loading your car and trailer can serious affect its steering and braking perfor- mance causing a crash in which could cause serious injury or death.
Without Brake Type
5. Always secure items in the trailer to prevent load shift while driving.
6. Check the condition and air pressure of all
tires on the trailer and your car. Low tire pressure can seriously affect the handling. Also check the spare tire.
7. The vehicle/trailer combination is more af-
fected by crosswind and buffeting. When being passed by a large vehicle, keep a constant speed and steer straight ahead. If there is too much wind buffeting slow down to get out of the other vehicle’s air turbulence.
8. When parking your car and trailer, especially
on a hill, be sure to follow all the normal precautions. Turn your front wheel into the curb, set the parking brake firmly, and put the transaxle in 1st or Reverse (manual) or Park (automatic). In addition, place wheel chocks at each of the trailer’s tires.
9. If the trailer has electric brakes, start your vehicle and trailer moving, and then apply the trailer brake controller by hand to be sure the brakes are working. This lets you check your electrical connection at the same time.
10. During your trip, check occasionally to be
sure that the load is secure, and that the lights and any trailer brakes are still working.
11. Avoid jerky starts, sudden acceleration or sudden stops.
12. Avoid sharp turns and rapid lane changes.
13. Avoid holding the brake pedal down too long or too frequently. This could cause the brakesto overheat, resulting in reduced braking effi- ciency. 14. When going down a hill, shift into a lower gear
and use the engine braking effect. When ascending a long grade, downshift the transaxle to a lower gear and reduce speed to reduce chances of engine overloading and/or overheating.
15. If you have to stop while going uphill, do not
hold the vehicle in place by pressing on the accelerator. This can cause the automatic transaxle to overheat. Use the parking brake or footbrake.
NOTE: When towing check transaxle fluid more fre- quently. CAUTION: If overheating should occur when towing, (temperature gauge reads near red zone), taking the following action may reduce or eliminate the problem.
1. Turn off the air conditioner.
2. Reduce highway speed.
3. Select a lower gear when going uphill.
4. While in stop and go traffic, place the gear selection in park or neutral and idle the engineat a higher speed.
C190F02A-GAT Trailer or Vehicle Towing Tips
1. Before towing, check hitch and safety chain
connections as well as proper operation of the trailer running lights, brake lights, and turn signals.
2. Always drive your vehicle at a moderate
speed (Less than 100 km/h).
3. Trailer towing requires more fuel than normal
conditions.
4. To maintain engine braking efficiency and
electrical charging performance, do not use fifth gear (manual transaxle) or overdrive (automatic transaxle).

WHAT TO DO IN AN EMERGENCY
3-2
When jump starting, wear protective glasses and be careful not to get acid on yourself, your clothing or on the car.
o If you should accidentally get acid on your
skin or in your eyes, immediately remove any contaminated clothing and flush the area with clear water for at least 15 minutes. Then promptly obtain medical attention. If you must be transported to an emergency facility, con- tinue to apply water to the affected area with a sponge or cloth.
o The gas produced by the battery during the
jump-start operation is highly explosive. Do not smoke or allow a spark or an open flame in the vicinity.
o The battery being used to provide the jump
start must be 12-volt. If you cannot determine that it is a 12-volt battery, do not attempt to use it for the jump start.
o To jump start a car with a discharged battery,
follow this procedure exactly:
1. If the booster battery is installed in another vehicle, be sure the two vehicles are nottouching.
2. Turn off all unnecessary lights and acces-
sories in both vehicles. 3. Attach the clamps of the jumper cable in the
exact location shown. First, attach one clamp of the jumper cable to the positive (+) post or cable of the discharged battery. Then attach the other end of the same cable to the positive (+) post or cable of the booster battery. Next, using the other cable, attach one clamp to the negative (-) post or cable of the booster battery. Then attach the other end of that cable to a solid metal part of the engine away from the battery. Do not connect the cable to any moving part.
4. Start the engine in the car with the booster
battery and let it run for a few minutes. This will help to assure that the booster battery is fully charged. During the jumping operation, run the engine in this vehicle at about 2,000 rpm.
5. Start the engine in the car with the discharged
battery using the normal starting procedure. After the engine starts, leave the jumper cables connected and let the engine run at fast idle or about 2,000 rpm for several min- utes.
6. Carefully remove the jumper cables in the
reverse order of attachment.
If you do not know why your battery became discharged (because the lights were left on, etc.), have the charging system checked by your Hyundai dealer. D030A02A-AAT IF THE ENGINE OVERHEATS If your temperature gauge indicates overheating, you experience a loss of power, or hear loud pinging or knocking, the engine is probably too hot. If this happens to you, you should:
1. Pull off the road and stop as soon as it is safe
to do so.
2. Place the gear selector lever in "P" (auto- matic), or neutral (manual transaxle) and set the parking brake. If the air conditioning is on, turn it off.
3. If engine coolant is running out under the car or steam is coming out from the hood, stop the engine. Do not open the hood until the engine coolant has stopped running or the steaming has stopped. If there is no visible loss of engine coolant and no steam, leave the engine running and check to be sure the engine cooling fan is operating. If the fan is not running, turn the engine off.
4. Check to see if the water pump drive belt is
missing. If it is not missing, check to see that it is tight. If the drive belt seems to be satis- factory, check for coolant leaking from the radiator, hoses or under the car. (If the air conditioning had been in use, it is normal for cold water to be draining from it when you stop).

WHAT TO DO IN AN EMERGENCY 3-3
WARNING: While the engine is running, keep hair, hands, and clothing away from moving parts such as the fan and drive belts to prevent injury.
5. If the water pump drive belt is broken or
coolant is leaking out, stop the engine im- mediately and call the nearest Hyundai deal- er for assistance.
WARNING: Do not remove the radiator cap when the engine is hot. This can allow coolant to be blown out of the opening and cause serious burns. WARNING (Diesel only): Never work on injection system with engine running or within 30 seconds after shutting off engine. High pressure pump, rail, injec- tors and high pressure pipes are subject to high pressure even after the engine stopped. The fuel jet produced by fuel leaks may cause serious injury, if it touch the body. People using pacemakers should not move than 30cm closer to the ECU or wiring harness within the engine room while engine is running, since the high currents in the Common Rail system produce considerable magnetic fields. 2. The spare tire should only be used temporari-
ly and should be returned to the luggage compartment as soon as the original tire can be repaired or replaced.
3. Continuous use at speeds of over 80 km/h (50 mph) is not recommended.
4. As the temporary spare tire is specifically designed for your car, it should not be used on any other vehicle.
5. The temporary spare tire should not be used
on any other wheels, nor should standard tires, snow tires, wheel covers or trim rings be used with the temporary spare wheel. If such use is attempted, damage to these items or other car components may occur.
6. The temporary spare tire pressure should be
checked once a month while the tire is stored.
CAUTION:
o Do not use snow chains with your tempo- rary spare tire.
o Do not use more than one temporary spare tire at a time.
D040A01FC-GAT TEMPORARY SPARE TIRE The following instructions for the temporary spare tire should be observed:
1. Check inflation pressure as soon as possible
after installing the spare tire, and adjust to the specified pressure. The tire pressure should be periodically checked and maintained at the specified pressure while the tire is stored.
Inflation Pressure
Tire Size
T115/70R(D)15 420 kPa (60 psi)
Spare Tire Pressure
6. If you cannot find the cause of the overheat-
ing, wait until the engine temperature has returned to normal. Then, if the engine cool- ant has been lost, carefully remove the radia- tor cap and add engine coolant to bring the fluid level in the reservoir up to the halfway mark.
7. Proceed with caution, keeping alert for fur- ther signs of overheating. If overheating hap- pens again, call a Hyundai dealer for assis- tance.
CAUTION: Serious loss of engine coolant indicates there is a leak in the cooling system and this should be checked as soon as possible by a Hyundai dealer.

DO-IT-YOURSELF MAINTENANCE
6-4
G020A01A-AAT
GENERAL CHECKS Engine Compartment
The following should be checked regularly:
o Engine oil level and condition
o Transaxle fluid level and condition
o Brake fluid level
o Clutch fluid level
o Engine coolant level
o Windshield washer fluid level
o Accessory drive belt condition
o Engine coolant hose condition
o Fluid leaks (on or below components)
o Power steering fluid level
o Battery condition
o Air filter condition
G020B01A-AAT
Vehicle Exterior The following should be checked monthly:
o Overall appearance and condition
o Wheel condition and wheel nut torque
o Exhaust system condition
o Light condition and operation
o Windshield glass condition
o Wiper blade condition
o Paint condition and body corrosion
o Fluid leaks
o Door and hood lock condition
o Tire pressure and condition (including spare tire) G020C01A-AAT
Vehicle Interior
The following should be checked each time when the vehicle is driven:
o Lights operation
o Windshield wiper operation
o Horn operation
o Defroster, heating system operation (and air conditioning, if installed)
o Steering operation and condition
o Mirror condition and operation
o Turn signal operation
o Accelerator pedal operation
o Brake operation, including parking brake
o Manual transaxle operation, including clutch operation
o Automatic transaxle operation, including "Park" mechanism operation
o Seat control condition and operation
o Seat belt condition and operation
o Sunvisor operation
If you notice anything that does not operate correctly or appears to be functioning incorrect-ly, inspect it carefully and seek assistance fromyour Hyundai dealer if service is needed. G030A01FC-GAT
CHECKING THE ENGINE OIL Gasoline EngineRecommended Oil
SSA6030B
20W-40 20W-50
10W-30 15W-40 15W-50
10W-40 10W-50
°C °F -25-13 2068 40104
-15
- 5 -10-14 0
32 1050
5W-40
5W-30
5W-20
Engine oil is essential to the performance and service of the engine. It is suggested that youcheck the oil level at least once a week innormal use and more often if you are on a tripor driving in severe conditions. SH, SG or SG/CD (API) multi-grade and fuel efficient oil is recommended. NOTE: SAE 5W-20 is not recommended for sus- tained high speed vehicle operation.