ECU Ram 3500 Chassis Cab 2020 Service Manual

280STARTING AND OPERATING
(Continued)
Towing Requirements — Tires
Do not attempt to tow a trailer while using a
compact spare tire.
Do not drive more than 50 mph (80 km/h) when towing while using a full size spare tire.
Proper tire inflation pressures are essential
to the safe and satisfactory operation of your
vehicle. Refer to “Tires” in “Servicing And
Maintenance” for proper tire inflation proce -
dures.
Check the trailer tires for proper tire inflation
pressures before trailer usage.
Check for signs of tire wear or visible tire
damage before towing a trailer. Refer to
“Tires” in “Servicing And Maintenance” for
the proper inspection procedure.
When replacing tires, refer to “Tires” in
“Servicing And Maintenance” for the proper
tire replacement procedures. Replacing tires
with a higher load carrying capacity will not
increase the vehicle's GVWR and GAWR
limits.
Towing Requirements — Trailer Brakes
Do not interconnect the hydraulic brake
system or vacuum system of your vehicle
with that of the trailer. This could cause inad -
equate braking and possible personal injury.
WARNING!
Make certain that the load is secured in the
trailer and will not shift during travel. When
trailering cargo that is not fully secured,
dynamic load shifts can occur that may be
difficult for the driver to control. You could
lose control of your vehicle and have a colli -
sion.
When hauling cargo or towing a trailer, do
not overload your vehicle or trailer. Over -
loading can cause a loss of control, poor
performance or damage to brakes, axle,
engine, transmission, steering, suspension,
chassis structure or tires.
Safety chains must always be used
between your vehicle and trailer. Always
connect the chains to the hook retainers of
the vehicle hitch. Cross the chains under
the trailer tongue and allow enough slack
for turning corners.
Vehicles with trailers should not be parked
on a grade. When parking, apply the
parking brake on the tow vehicle. Put the
tow vehicle transmission in PARK. For
four-wheel drive vehicles, make sure the
transfer case is not in NEUTRAL. Always,
block or "chock" the trailer wheels.
GCWR must not be exceeded.
Total weight must be distributed between
the tow vehicle and the trailer such that the
following four ratings are not exceeded :
GVWR
GTW
GAWR
Tongue weight rating for the trailer
hitch utilized.
WARNING! (Continued)

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STARTING AND OPERATING289
(Continued)
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 allowed 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 instruc -
tions.

2. Drive the rear wheels onto the tow dolly.
3. Firmly apply the parking brake. Place auto -
matic transmission in PARK.
4. Properly secure the rear wheels to the dolly, following the dolly manufacturer's instruc -
tions.
5. Turn the ignition to the OFF position and remove the key fob.
6. Install a suitable clamping device, designed for towing, to secure the front wheels in the
straight position.
Recreational Towing — Four-Wheel Drive
Models
NOTE:
Both the manual shift and electronic shift
transfer cases must be shifted into N (Neutral)
for recreational towing. Automatic transmis -
sions must be shifted into PARK for recreational
towing. Refer to the following for the proper
transfer case N (Neutral) shifting procedure for
your vehicle.
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 internal parts.
CAUTION!
DO NOT dolly tow any 4WD vehicle. Towing
with only one set of wheels on the ground
(front or rear) will cause severe transmis -
sion 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.
The transmission must be placed in PARK
for recreational towing.
Towing this vehicle in violation of the above
requirements can cause severe transmis -
sion and/or transfer case damage.
Damage from improper towing is not
covered under the New Vehicle Limited
Warranty.
5

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IN CASE OF EMERGENCY307
F0940 Amp Green (SSV &
Cummins Diesel) –
Aux Relay Output / Diesel Fuel Heater – If Equipped
F09 30 Amp Pink –Brake Vacuum Pump – If Equipped (HD Only)
F10 40 Amp Green –Body Controller / Exterior Lighting #2
F11 30 Amp Pink –PWR - Trailer Tow Electric Brake Batt Feed – If Equipped
(DS 1500 Only)
F11 40 Amp Green –Brake System Module (ECU and Valves) (HD Only)
F12 40 Amp Green –Body Controller #3
F13 40 Amp Green –Blower Motor
F14 40 Amp Green –Body Controller #4 / Exterior Lighting

F15 30 Amp Pink
40 Amp Green –
–Power Side Steps – If Equipped (HD Only)
Extra Fuse - SSV Only
F16 30 Amp Pink –Smart-Bar Module – If Equipped (HD Only)
F17 30 Amp Pink –Winch Control Module – If Equipped (HD Only)
F19 20 Amp Blue (DS 1500 LD
Diesel)
30 Amp Pink (Cummins Diesel) –
SCR – If Equipped
F20 30 Amp Pink –Passenger Door Module
F21 30 Amp Pink –Drive Train Control Module
Cavity Cartridge Fuse Micro Fuse Description
6

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316IN CASE OF EMERGENCY

Jack Warning Label
1. If equipped, remove the spare wheel, jack,
and tools from storage.

2. Using the lug wrench, loosen, but do not remove, the lug nuts by turning them coun -
terclockwise one turn while the wheel is still
on the ground.
3. When changing the front wheel, assemble the jack driver to the jack and connect the
jack driver to the extension tube. Place the
jack under the axle as close to the tire as
possible with the jack driver extending to
the front. Connect the extension tubes and
lug wrench.

Front Jacking Locations

When changing a rear wheel, assemble the
jack driver to the jack and connect the jack
driver to the extension tubes. Securely
place the jack under the sway bar bracket (unless both tires are flat on one side, then
place jack under shock bracket) facing for
-
ward in vehicle. Connect the extension
tubes and lug wrench.

Rear Jacking Location

Before raising the wheel off the ground,
make sure that the jack will not damage
surrounding truck parts and adjust the jack
position as required.
NOTE:
If the jack will not lower by turning the dial
(thumbwheel) by hand, it may be necessary to
use the jack driver in order to lower the jack.
4. By rotating the lug wrench clockwise, raise the vehicle until the wheel just clears the
surface.
Only use the jack in the positions indicated
and for lifting this vehicle during a tire
change.
If working on or near a roadway, be
extremely careful of motor traffic.
To assure that spare tires, flat or inflated,
are securely stowed, spares must be
stowed with the valve stem facing the
ground.
CAUTION!
Do not attempt to raise the vehicle by jacking
on locations other than those indicated in the
Jacking Instructions for this vehicle.
WARNING! (Continued)

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IN CASE OF EMERGENCY323

Engaging The Access Port

6. Move the gear selector to the NEUTRAL position.
7. The vehicle may then be started in NEUTRAL.
MANUAL PARK RELEASE — 8 – SPEED
TRANSMISSION
To push or tow the vehicle in cases where the
transmission will not shift out of PARK (such as
a depleted battery), a Manual Park Release is
available.
Manual Park Release Cover
Manual Park Release Pull Strap

WARNING!
Always secure your vehicle by fully applying
the parking brake before activating the
Manual Park Release. In addition, you should
be seated in the driver’s seat with your foot
firmly on the brake pedal when activating the
Manual Park Release. Activating the Manual
Park Release will allow your vehicle to roll
away if it is not secured by the parking brake,
or by proper connection to a tow vehicle.
Activating the Manual Park Release on an
unsecured vehicle could lead to serious injury
or death for those in or around the vehicle.
6

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324IN CASE OF EMERGENCY
Follow these steps to activate the Manual Park
Release:

1. Firmly apply the parking brake.

2. Using a small screwdriver or similar tool,
remove the Manual Park Release access
cover, which is just above the parking brake
release handle, below and to the left of the
steering column.
3. Press and maintain firm pressure on the brake pedal.
4. Using the screwdriver or similar tool, push the Manual Park Release lever locking tab
(just below the middle of the lever) upwards.
5. While holding the locking tab in the disen -
gaged position, pull the tether strap to
rotate the lever rearward, until it locks in
place pointing towards the driver's seat.
Release the locking tab and verify that the
Manual Park Release lever is locked in the
released position. 6. The vehicle is now out of PARK and can be
towed. Release the parking brake only when
the vehicle is securely connected to a tow
vehicle.
To Reset The Manual Park Release:

1. Push the locking tab to the right, to unlock the lever.

2. Rotate the Manual Park Release lever forward to its original position, until the
locking tab snaps into place to secure the
lever.
3. Pull gently on the tether strap to confirm that the lever is locked in its stowed posi-
tion.
4. Re-install the access cover.FREEING A STUCK VEHICLE
If your vehicle becomes stuck in mud, sand, or
snow, it can often be moved using a rocking
motion. Turn the steering wheel right and left to
clear the area around the front wheels. Then
shift back and forth between DRIVE (D) and
REVERSE (R), while gently pressing the acceler -
ator. Use the least amount of accelerator pedal
pressure that will maintain the rocking motion,
without spinning the wheels or racing the
engine.

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326IN CASE OF EMERGENCY
TOWING A DISABLED VEHICLE
This section describes procedures for towing a disabled vehicle using a commercial towing service. If the transmission and drivetrain are operable,
disabled vehicles may also be towed as described under “Recreational Towing” in the “Starting And Operating” section.
Proper towing or lifting equipment is required to
prevent damage to your vehicle. Use only tow
bars and other equipment designed for this
purpose, following equipment manufacturer’s
instructions. Use of safety chains is mandatory.
Attach a tow bar or other towing device to main
structural members of the vehicle, not to
bumpers or associated brackets. State and
local laws regarding vehicles under tow must be
observed. If you must use the accessories (wipers,
defrosters, etc.) while being towed, the ignition
must be in the ON/RUN mode, not the ACC
mode.
If the key fob is unavailable or the vehicle's
battery is discharged, refer to “Manual Park
Release” or “Gear Selector Override” in this
section for instructions on shifting the auto
-
matic transmission out of PARK for towing.
Towing Condition Wheels OFF The
Ground 2WD Models
4WD Models
Flat Tow NONE If transmission is operable:

• Transmission in NEUTRAL
• 30 mph (48 km/h) max speed
• 15 miles (24 km) max distance (6–speed
transmission)
• 30 miles (48 km) max distance (8–speed
transmission) See instructions in “Recreational Towing” under
“Starting And Operating”

• Auto Transmission in PARK
• Transfer Case in NEUTRAL
• Tow in forward direction
Wheel Lift Or Dolly Tow Front
NOT ALLOWED
Rear OK NOT ALLOWED

Flatbed ALL
BEST METHOD BEST METHOD
CAUTION!
Do not use sling type equipment when
towing. Vehicle damage may occur.
When securing the vehicle to a flat bed
truck, do not attach to front or rear suspen-
sion components. Damage to your vehicle
may result from improper towing.

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SERVICING AND MAINTENANCE351
3. Remove the air cleaner filter element from
the housing assembly.

Air Cleaner Filter

Engine Air Cleaner Filter Installation
NOTE:
Inspect and clean the housing if dirt or debris is
present before replacing the air filter element.

1. Install the air cleaner filter element into the housing assembly with the air cleaner filter
inspection surface facing downward.

2. Install the air cleaner cover onto the housing assembly locating tabs. 3. Install screws to secure the air cleaner
cover to the housing assembly.
Air Conditioner Maintenance
For best possible performance, your air condi -
tioner should be checked and serviced by an
authorized dealer at the start of each warm
season. This service should include cleaning of
the condenser fins and a performance test.
Drive belt tension should also be checked at
this time.
Refrigerant Recovery And Recycling R-134a
— If Equipped
R-134a Air Conditioning Refrigerant is a hydro -
fluorocarbon (HFC) that is an ozone-friendly
substance. The manufacturer recommends
that air conditioning service be performed by an
authorized dealer or other service facilities
using recovery and recycling equipment.
NOTE:
Use only manufacturer approved A/C system
PAG compressor oil and refrigerants.
1 — Air Cleaner Filter
2 — Air Cleaner Filter Inspection Surface
WARNING!
Use only refrigerants and compressor lubri -
cants approved by the manufacturer for
your air conditioning system. Some unap -
proved refrigerants are flammable and can
explode, injuring you. Other unapproved
refrigerants or lubricants can cause the
system to fail, requiring costly repairs.
Refer to Warranty Information Book, for
further warranty information.
The air conditioning system contains refrig -
erant under high pressure. To avoid risk of
personal injury or damage to the system,
adding refrigerant or any repair requiring
lines to be disconnected should be done by
an experienced technician.
CAUTION!
Do not use chemical flushes in your air
conditioning system as the chemicals can
damage your air conditioning components.
Such damage is not covered by the New
Vehicle Limited Warranty.
7

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SERVICING AND MAINTENANCE355
If water is detected in the water separator while
the engine is running, or while the ignition
switch is in the ON position, the “Water In Fuel
Indicator Light” will illuminate and an audible
chime will be heard five times. At this point you
should stop the engine and drain the water from
both of the filters.
If the “Water In Fuel Indicator Light” comes on
and a single chime is heard while you are
driving, or with the ignition switch in the ON
position, there may be a problem with your
water separator wiring or sensor. See an autho -
rized dealer for service. Upon proper draining of the water from both
fuel filters, the “Water In Fuel Indicator Light”
will remain illuminated for approximately 10
seconds. If the water was drained while the
engine was running, the “Water In Fuel Indicator
Light” may remain on for approximately three
minutes.
NOTE:
Care should be taken in disposing of used fluids
from your vehicle. Used fluids, indiscriminately
discarded, can present a problem to the envi
-
ronment. Contact an authorized dealer, service
station, or government agency for advice on
recycling programs and for where used fluids
and filters can be properly disposed of in your
area.
Drain the fuel/water separator filters when the
“Water In Fuel Indicator Light” is ON. Within
10 minutes of vehicle shutdown, turn the
engine mounted filter drain valve (located on
the side of the filter assembly) counterclock -
wise quarter turn, and turn the under body
mounted filter drain valve (located on the
bottom of the filter assembly) counterclockwise
wise 1 full turn. Then turn the ignition switch to the ON position, and allow any accumulated
water to drain. Leave the drain valve open until
all water and contaminants have been
removed. When clean fuel is visible, close the
drain valve following these guidelines:

1. Rotate the drain clockwise to close until
you feel resistance from the internal seal.

2. Continue turning the drain half of a turn to properly compress the seal.
NOTE:
Over-compression of the seal due to over-tight -
ening of the drain will damage the seal, cause a
leak, and require the entire sensor to be
replaced.
3. Turn the ignition switch to OFF.
The sensor drain should not be over-tightened
during normal service operations to avoid
internal damage and future fuel leaks. The
drain should be closed and secured without the
use of tools.
If more than a couple ounces/milliliters of fuel
have been drained, follow the directions for
“Priming If The Engine Has Run Out Of Fuel.”
CAUTION!
Do not drain the fuel/water separator filter
when the engine is running.
Diesel fuel will damage blacktop paving
surfaces. Drain the filter into an appro-
priate container.
CAUTION!
If the “Water In Fuel Indicator Light” remains
on, DO NOT START the engine before you
drain water from the fuel filters to avoid
engine damage.
7

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SERVICING AND MAINTENANCE367
(Continued)
Brake System
In order to ensure brake system performance,
all brake system components should be
inspected periodically. Refer to the “Mainte -
nance Plan” in this section for the proper main -
tenance intervals.
Fluid Level Check — Brake Master Cylinder
The fluid level of the master cylinder should be
checked when performing under the hood
service or immediately if the brake system
warning lamp indicates system failure.
If necessary, add fluid to bring level within the
designated marks on the side of the reservoir of
the brake master cylinder. Be sure to clean the
top of the master cylinder area before removing
cap. With disc brakes the fluid level can be expected
to fall as the brake linings wear. However, an
unexpected drop in fluid level may be caused by
a leak and a system check should be
conducted.
Refer to “Fluids And Lubricants” in “Technical
Specifications” for further information.
WARNING!
Riding the brakes can lead to brake failure
and possibly a collision. Driving with your foot
resting or riding on the brake pedal can result
in abnormally high brake temperatures,
excessive lining wear, and possible brake
damage. You would not have your full braking
capacity in an emergency.WARNING!
Use only manufacturer's recommended
brake fluid. Refer to “Fluids And Lubri
-
cants” in “Technical Specifications” for
further information. Using the wrong type of
brake fluid can severely damage your brake
system and/or impair its performance. The
proper type of brake fluid for your vehicle is
also identified on the original factory
installed hydraulic master cylinder reser -
voir.
To avoid contamination from foreign matter
or moisture, use only new brake fluid or
fluid that has been in a tightly closed
container. Keep the master cylinder reser -
voir cap secured at all times. Brake fluid in
a open container absorbs moisture from
the air resulting in a lower boiling point. This
may cause it to boil unexpectedly during
hard or prolonged braking, resulting in
sudden brake failure. This could result in a
collision.
Overfilling the brake fluid reservoir can
result in spilling brake fluid on hot engine
parts, causing the brake fluid to catch fire.
Brake fluid can also damage painted and
vinyl surfaces, care should be taken to
avoid its contact with these surfaces.
Do not allow petroleum based fluid to
contaminate the brake fluid. Brake seal
components could be damaged, causing
partial or complete brake failure. This could
result in a collision.
WARNING! (Continued)
7

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