• The transmission fluid has reached an adequate tem-
perature.
• The engine coolant has reached an adequate tempera-
ture.
• Vehicle speed is sufficiently high.
• The TOW/HAUL switch has not been activated.
• The driver is not heavily pressing the accelerator.
When To Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting occurs,
push the TOW/HAUL switch to activate TOW/HAUL
mode. This will improve performance and reduce the
potential for transmission overheating or failure due to
excessive shifting. When operating in TOW/HAUL mode,
transmission upshifts are delayed, and the transmission
will automatically downshift (for engine braking) when the
throttle is closed and/or during steady braking maneu-
vers. The “TOW/HAUL Indicator Light” will illuminate in the
instrument cluster to indicate that TOW/HAUL mode has
been activated. Pushing the switch a second time restores
normal operation. Normal operation is always the default
at engine start-up. If TOW/HAUL mode is desired, the
switch must be pushed each time the engine is started. TOW/HAUL Switch334 STARTING AND OPERATING
WARNING!Do not use the “TOW/HAUL” feature when driving in
icy or slippery conditions. The increased engine brak-
ing can cause the rear wheels to slide, and the vehicle
to swing around with the possible loss of vehicle
control, which may cause an accident possibly result-
ing in personal injury or death.
Torque Converter Clutch
A feature designed to improve fuel economy has been
included in the automatic transmission on your vehicle. A
clutch within the torque converter engages automatically
at calibrated speeds. This may result in a slightly different
feeling or response during normal operation in the upper
gears. When the vehicle speed drops or during some
accelerations, the clutch automatically disengages. NOTE:
• The torque converter clutch will not engage (and 66RFE-
equipped trucks will not shift to sixth gear), until the
transmission fluid and engine coolant are warm [usually
after 1 to 3 miles (2 to 5 km) of driving]. Because engine
speed is higher when the torque converter clutch is not
engaged, it may seem as if the transmission is not
shifting properly when cold. This is normal. Using the
Electronic Range Select (ERS) shift control, when the
transmission is sufficiently warm, will demonstrate that
the transmission is able to shift into and out of Over-
drive.
• If the vehicle has not been driven for several days, the
first few seconds of operation after shifting the transmis-
sion into gear may seem sluggish. This is due to the fluid
partially draining from the torque converter into the
transmission. This condition is normal and will not
cause damage to the transmission. The torque converter
will refill within five seconds after starting the engine. 5STARTING AND OPERATING 335
CAUTION!Prolonged operation of the steering system at the end
of the steering wheel travel will increase the steering
fluid temperature and it should be avoided when
possible. Damage to the power steering pump may
occur.
Power Steering Fluid Check
Checking the power steering fluid level at a defined service
interval is not required. The fluid should be checked at
every oil change if a leak is suspected, abnormal noises are
apparent, and/or the system is not functioning as antici-
pated. Coordinate inspection efforts through an authorized
dealer.
CAUTION!Do not use chemical flushes in your power steering
system as the chemicals can damage your power steer-
ing components. Such damage is not covered by the
New Vehicle Limited Warranty. WARNING!Fluid level should be checked on a level surface and
with the engine off to prevent injury from moving
parts and to ensure accurate fluid level reading. Do not
overfill. Use only manufacturer’s recommended power
steering fluid.
If necessary, add fluid to restore to the proper indicated
level. With a clean cloth, wipe any spilled fluid from all
surfaces. Refer to “Fluids, Lubricants And Genuine Parts”
in “Maintaining Your Vehicle” for further information.
PARKING BRAKE
Before leaving the vehicle, make sure that the parking
brake is fully applied, the engine is off and the key fob is
removed from the ignition switch. Also, be certain to leave
an automatic transmission in PARK, or manual transmis-
sion in REVERSE or first gear.
The foot operated parking brake is located below the lower
left corner of the instrument panel. To apply the parking
brake, firmly push the parking brake pedal fully. To release
the parking brake, pull the parking brake release handle.350 STARTING AND OPERATING
WARNING! (Continued)• Be sure the parking brake is fully disengaged before
driving; failure to do so can lead to brake failure and
a collision.
• Always fully apply the parking brake when leaving
your vehicle or it may roll and cause damage or
injury. Also, be certain to leave an automatic trans-
mission in PARK, a manual transmission in RE-
VERSE or first gear. Failure to do so may cause the
vehicle to roll and cause damage or injury.
CAUTION!If the “Brake Warning Light” remains on with the
parking brake released, a brake system malfunction is
indicated. Have the brake system serviced by an au-
thorized dealer immediately.
BRAKE SYSTEM
If power assist is lost for any reason (for example, repeated
brake applications with the engine off), the brakes will still
function. However, you will experience a substantial in-
crease in braking effort to stop the vehicle. If either the front or rear hydraulic system loses normal
braking capability, the remaining system will still function
with some loss of overall braking effectiveness. This will be
evident by increased pedal travel during application,
greater pedal force required to slow or stop, and activation
of the “Brake Warning Light” and the “ABS Warning
Light” (if equipped) during brake use.
The brake system power assist is provided by a hydro-boost
unit which shares fluid with the power steering system. You
may experience some clicking or hissing noises from the
hydro-boost system during hard braking conditions.
NOTE: Under cold temperatures, pedal effort will be
higher than normal until the power steering fluid reaches
operating temperature.
Hydraulic Brake Assist
The brake system power assist is provided by a hydro-boost
unit which shares fluid with the power steering system. You
may experience some clicking or hissing noises from the
hydro-boost system during hard braking conditions.
NOTE: Under cold temperatures, pedal effort will be
higher than normal until the power steering fluid reaches
operating temperature.352 STARTING AND OPERATING
Towing Tips
Before setting out on a trip, practice turning, stopping and
backing the trailer up in an area away from heavy traffic.
Automatic Transmission — If Equipped
The DRIVE range can be selected when towing. The
transmission controls include a drive strategy to avoid
frequent shifting when towing. However, if frequent shift-
ing does occur while in DRIVE, select TOW/HAUL mode
or select a lower gear range (using the Electronic Range
Select (ERS) shift control).
NOTE: Using TOW/HAUL mode, or selecting a lower
gear range (using the ERS shift control) while operating the
vehicle under heavy loading conditions will improve per-
formance and extend transmission life by reducing exces-
sive shifting and heat build up. This action will also
provide better engine braking.
When towing a loaded trailer up steep grades at low
speeds (20 mph [32 km/h] or below), holding your vehicle
in first gear (using the ERS shift control) can help to avoid
transmission overheating. If you regularly tow a trailer for more than 45 minutes of
continuous operation, then change the transmission fluid
and filter(s) as specified for police, taxi, fleet, or frequent
trailer towing. Refer to the “Maintenance Schedule” for
the proper maintenance intervals.
NOTE: Check the automatic transmission fluid level be-
fore towing.
Tow/Haul Mode
To reduce potential for automatic transmission overheat-
ing, activate TOW/HAUL mode when driving in hilly
areas, or select a lower gear range (using the Electronic
Range Select (ERS) shift control) on more severe grades.
Electronic Speed Control — If Equipped
• Do not use in hilly terrain or with heavy loads.
• When using the speed control, if you experience speed
drops greater than 10 mph (16 km/h), disengage until
you can get back to cruising speed.
• Use speed control in flat terrain and with light loads to
maximize fuel efficiency. 5STARTING AND OPERATING 415
Recreational Towing — Two-Wheel Drive Models
DO NOT flat tow this vehicle. Damage to the drivetrain
will result.
Recreational towing (for two-wheel drive models) is al-
lowed ONLY if the rear wheels are OFF the ground. This
may be accomplished using a tow dolly or vehicle trailer. If
using a tow dolly, follow this procedure:
1. Properly secure the dolly to the tow vehicle, following
the dolly manufacturer’s instructions.
2. Drive the rear wheels onto the tow dolly.
3. Firmly apply the parking brake. Place automatic trans-
mission in PARK, manual transmission in gear (not in
NEUTRAL).
4. Properly secure the rear wheels to the dolly, following
the dolly manufacturer’s instructions.
5. Turn the ignition OFF and remove the key fob.
6. Install a suitable clamping device, designed for towing,
to secure the front wheels in the straight position. CAUTION!• Towing with the rear wheels on the ground will
cause severe transmission damage. Damage from
improper towing is not covered under the New
Vehicle Limited Warranty.
• Do not disconnect the driveshaft because fluid may
leak from the transmission, causing damage to inter-
nal parts.
Recreational Towing — Four-Wheel Drive Models
NOTE: Both the manual shift and electronic shift transfer
cases must be shifted into NEUTRAL (N) for recreational
towing. Automatic transmissions must be shifted into
PARK for recreational towing. Manual transmissions must
be placed in gear (NOT in NEUTRAL) for recreational
towing. Refer to the following for the proper transfer case
NEUTRAL (N) shifting procedure for your vehicle.420 STARTING AND OPERATING
CAUTION!• DO NOT dolly tow any 4WD vehicle. Towing with
only one set of wheels on the ground (front or rear)
will cause severe transmission and/or transfer case
damage. Tow with all four wheels either ON the
ground, or OFF the ground (using a vehicle trailer).
• Tow only in the forward direction. Towing this
vehicle backwards can cause severe damage to the
transfer case.
• Before recreational towing, the transfer case must be
in NEUTRAL. To be certain the transfer case is fully
in NEUTRAL, perform the procedure outlined under
“Shifting Into NEUTRAL”. Internal transmission
damage will result, if the transfer case is not in
NEUTRAL during towing.
• Automatic transmissions must be placed in PARK,
and manual transmissions must be placed in gear
(not in Neutral) for recreational towing.
• Towing this vehicle in violation of the above require-
ments can cause severe transmission and/or transfer
case damage. Damage from improper towing is not
covered under the New Vehicle Limited Warranty. (Continued) CAUTION! (Continued)• Do not disconnect the rear driveshaft because fluid
will leak from the transfer case, causing damage to
internal parts.
• Do not use a bumper-mounted clamp-on tow bar on
your vehicle. The bumper face bar will be damaged.
Shifting Into NEUTRAL (N)
Use the following procedure to prepare your vehicle for
recreational towing.
WARNING!You or others could be injured or killed if you leave the
vehicle unattended with the transfer case in the NEU-
TRAL (N) position without first fully engaging the
parking brake. The transfer case NEUTRAL (N) position
disengages both the front and rear driveshafts from the
powertrain, and will allow the vehicle to roll, even if the
automatic transmission is in PARK (or manual transmis-
sion is in gear). The parking brake should always be
applied when the driver is not in the vehicle. 5STARTING AND OPERATING 421
MAINTAINING YOUR VEHICLECONTENTS ENGINE COMPARTMENT — 6.4L .......... .447
ONBOARD DIAGNOSTIC SYSTEM (OBD II) . . . .448
▫ Onboard Diagnostic System (OBD II)
Cybersecurity ........................ .448
▫ Loose Fuel Filler Cap Message ............ .449
EMISSIONS INSPECTION AND
MAINTENANCE PROGRAMS ............. .449
REPLACEMENT PARTS .................. .450
DEALER SERVICE ...................... .450
MAINTENANCE PROCEDURES ............ .451
▫ Engine Oil .......................... .451
▫ Engine Oil Filter ...................... .453
▫ Engine Air Cleaner Filter ................ .454
▫ Accessory Drive Belt Inspection ........... .456
▫ Maintenance-Free Battery ................ .458 ▫ Air Conditioner Maintenance ............. .459
▫ Front Prop Shaft Lubrication —
Four-Wheel Drive Models ................ .465
▫ Body Lubrication ..................... .466
▫ Windshield Wiper Blades ................ .466
▫ Adding Washer Fluid .................. .469
▫ Exhaust System ....................... .470
▫ Cooling System ....................... .471
▫ Brake System ........................ .475
▫ Rear Axle And 4x4 Front Driving Axle
Fluid Level .......................... .476
▫ Transfer Case ........................ .477
▫ Automatic Transmission — If Equipped ..... .478
▫ Appearance Care And Protection From
Corrosion ........................... .4807