2021 RAM CHASSIS CAB ECU

376SERVICING AND MAINTENANCE
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”
Ú page 378
ENGINE MOUNTED FUEL FILTER
R
EPLACEMENT
NOTE:
Using a fuel filter that does not meet the
manufacturer's filtration and water sepa -
rating requirements can severely impact fuel
system life and reliability.
The engine mounted filter housing is
equipped with a No-Filter-No-Run (NFNR)
feature. Engine will not run if:
a. No filter is installed.
b. Inferior/Non-approved filter is used. Use of OEM filter is required to ensure
vehicle will run.

Engine Mounted Fuel Filter Assembly
1. Ensure engine is turned off.

2. Place drain pan under the fuel filter drain
hose.
3. Open the water drain valve a quarter turn counterclockwise and completely drain fuel
and water into the approved container.
4. Close the water drain valve.
5. Remove lid using a socket or strap wrench. Rotate counterclockwise for removal.
Remove used o-ring and discard it.
1 — Drain Valve
CAUTION!
Diesel fuel will damage blacktop paving
surfaces. Drain the filter into an appro-
priate container.
Do not prefill the fuel filter when installing a
new fuel filter. There is a possibility debris
could be introduced into the fuel filter
during this action. It is best to install the
filter dry and allow the in-tank lift pump to
prime the fuel system.

21_DPF_OM_EN_USC_t.book Page 376

SERVICING AND MAINTENANCE387
(Continued)
BRAKE SYSTEM
In order to ensure brake system performance,
all brake system components should be
inspected periodically Ú page 354.
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.

For further information Ú
page 444.
AUTOMATIC TRANSMISSION
Special Additives

The manufacturer strongly recommends against
using any special additives in the transmission.
Automatic Transmission Fluid (ATF) is an
engineered product and its performance may be
impaired by supplemental additives. Therefore,
do not add any fluid additives to the transmission.
The only exception to this policy is the use of special
dyes for diagnosing fluid leaks in six-speed
transmissions. Avoid using transmission sealers as
they may adversely affect seals.

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 Úpage 444. Using the wrong
type of brake fluid can severely damage
your brake system and/or impair its perfor -
mance. The proper type of brake fluid for
your vehicle is also identified on the original
factory installed hydraulic master cylinder
reservoir.

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 reservoir 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)
8

21_DPF_OM_EN_USC_t.book Page 387

SERVICING AND MAINTENANCE395
Power Distribution Center
The Power Distribution Center is located in the
engine compartment near the battery. This
center contains cartridge fuses, micro fuses,
relays, and circuit breakers. A description of
each fuse and component may be stamped on
the inside cover, otherwise the cavity number of
each fuse is stamped on the inside cover that
corresponds to the following chart.

Power Distribution Center Location

Cavity Cartridge FuseMicro Fuse Description
F01– –Spare
F02 60 Amp Yellow –ABS Pump Motor (HD Only)
F03 60 Amp Yellow –Rad Fan – If Equipped
F04 50 Amp Red 400W Inverter – If Equipped
F05 40 Amp Green –Compressor For Air Suspension – If Equipped
F06 40 Amp Green –Steering Torque Overlay Module (STOM)
F07 40 Amp Green –Starter Solenoid
F08 20 Amp Blue –NOX Sensor – If Equipped
F09 40 Amp Green –Diesel / Fuel Heater – If Equipped
F09 30 Amp Pink –Gas / Brake Vacuum Pump – If Equipped
F10 40 Amp Green –CBC #2 / Ext Lights
F11 40 Amp Green –Brake System Module (ECU and Valves)
8

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450
INDEX
 Pair (Link) Uconnect Phone To A Mobile
Phone............................................................ 260 WARRANTY INFORMATION...................... 447
A
Adaptive Cruise Control (ACC)
(Cruise Control)
.................................... 164, 166Adding Engine Coolant (Antifreeze)............... 384Adding Fuel.................................................... 196Additives, Fuel............................................... 434Adjust Down........................................................... 35Forward....................................................... 35Rearward..................................................... 35Up................................................................ 35Adjustable Pedals............................................ 40Advance Phone Connectivity......................... 266Air BagAir Bag Operation...................................... 305Air Bag Warning Light................................ 303Enhanced Accident Response......... 310, 352Event Data Recorder (EDR)....................... 352If Deployment Occurs................................ 309Knee Impact Bolsters................................ 305Maintaining Your Air Bag System.............. 311Maintenance............................................. 311
Redundant Air Bag Warning Light............. 303Transporting Pets..................................... 330Air Bag Light................................ 107, 303, 331Air Cleaner, Engine (Engine Air Cleaner
Filter)................................................... 369, 391Air Conditioner Maintenance........................ 371Air Conditioner Refrigerant.................. 371, 372Air Conditioner System................................. 371Air Conditioning................................................ 62Air Conditioning Filter....................................... 65Air Conditioning System................................... 64Air Conditioning, Operating Tips....................... 65Air Filter........................................................ 369Air PressureTires......................................................... 415AlarmSecurity Alarm....................................23, 108Alterations/ModificationsVehicle......................................................... 10Antifreeze (Engine Coolant).......................... 384Capacities................................................. 439Disposal................................................... 385Anti-Lock Brake System (ABS)...................... 273Anti-Lock Warning Light................................ 113Assist, Hill Start............................................. 280Audio Settings............................................... 253Audio Systems (Radio).................................. 220
Auto Down Power Windows..............................77Automatic Door Locks......................................28Automatic Headlights.......................................52Automatic Temperature Control (ATC)..............64Automatic Transmission....................... 141, 389Adding Fluid.............................................. 389Fluid And Filter Change............................. 389Fluid Change............................................. 389Fluid Level Check............................. 387, 388Fluid Type........................................ 390, 444Shifting..................................................... 146Special Additives...................................... 387Automatic Transmission Limp Home Mode... 145AutoPark....................................................... 120AUX Camera......................................... 188, 194Auxiliary Driving Systems.............................. 281Axle Fluid.....................................390, 391, 444Axle Lubrication................................... 390, 391
B
Back-Up......................................................... 186Back-Up Camera........................................... 186Battery................................................. 108, 366Blanket..................................................... 130Charging System Light.............................. 108Keyless Key Fob Replacement....................16Battery Saver Feature......................................54

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451
Belts, Seat
..................................................... 330Bluetooth Connecting To A Particular Mobile Phone Or Audio Device After Pairing
................262Body Builders Guide........................................ 10Body Mechanism Lubrication........................ 380B-Pillar Location............................................. 411Brake Assist System...................................... 274Brake Control System.................................... 274Brake Fluid.......................................... 387, 444Brake System...................................... 387, 431Fluid Check............................................... 387Master Cylinder......................................... 387Parking...................................................... 137Warning Light............................................ 107Brake/Transmission Interlock....................... 141Bulb Replacement......................................... 401Bulbs, Light.......................................... 332, 401
C
Cab Top Clearance Lights.............................. 405Camera.......................................................... 186Camera, AUX........................................ 188, 194Camera, Rear...................................... 186, 189Capacities, Antifreeze (Engine Coolant)......... 439Capacities, Fluid............................................ 439Caps, FillerOil (Engine)................................................ 364Power Steering.......................................... 163Radiator (Coolant Pressure)...................... 385
Car Washes................................................... 428Carbon Monoxide Warning............................ 333Cargo Light....................................................... 54CD................................................................. 255Cellular Phone.............................................. 269Center High Mounted Stop Light................... 405Center Seat Storage Compartment.................. 67Changing A Flat Tire...................................... 339Charge Air Cooler.......................................... 386Chart, Tire Sizing........................................... 407Check Engine Light (Malfunction
Indicator Light).............................................. 117Checking Your Vehicle For Safety................. 330Checks, Safety.............................................. 330Child Restraint.............................................. 312Child RestraintsBooster Seats........................................... 315Child Seat Installation..................... 323, 325How To Stow An unused ALR Seat Belt.... 322Infant And Child Restraints....................... 313Locating The LATCH Anchorages.............. 320Lower Anchors And Tethers For Children.. 317Older Children And Child Restraints......... 314Seating Positions...................................... 316Clean Air Gasoline......................................... 433CleaningWheels..................................................... 421Climate Control................................................ 58Automatic.................................................... 59Manual........................................................ 62
Cold Weather Operation................................ 122Compact Spare Tire...................................... 419Contract, Service........................................... 446Controls........................................................ 247Cooling Pressure Cap (Radiator Cap)............ 385Cooling System............................................. 383Adding Coolant (Antifreeze)...................... 384Coolant Level................................... 384, 386Cooling Capacity....................................... 439Disposal Of Used Coolant......................... 385Drain, Flush, And Refill............................. 384Inspection................................................. 386Points To Remember................................ 386Pressure Cap............................................ 385Radiator Cap............................................. 385Selection Of Coolant (Antifreeze)..... 384, 440Corrosion Protection..................................... 427Cruise Control (Speed Control)............. 164, 166Cruise Light................................................... 115Customer Assistance.................................... 445Cybersecurity................................................ 220
D
Daytime Running Lights...................................51Dealer Service............................................... 367Defroster, Rear Window...................................62Defroster, Windshield............................ 62, 331Delay (Intermittent) Wipers..............................57Deleting A Phone........................................... 262Diagnostic System, Onboard......................... 116
11

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454 J
Jack Location
................................................. 339Jack Operation............................................... 339Jacking And Tire Changing............................. 339Jump Starting................................................ 344
K
Key Fob Programming Additional Key Fobs
.............. 17Key Fob Battery Service (Remote
Keyless Entry).................................................. 16Key Fob Programming (Remote
Keyless Entry).................................................. 17Keyless Enter-N-Go........................26, 118, 123Passive Entry............................................... 26Keys................................................................. 15
L
Lane Change And Turn Signals........................ 54Lane Change Assist......................................... 54LaneSense.................................................... 183Latches.......................................................... 332Hood........................................................... 79Lead Free Gasoline........................................ 433Leaks, Fluid................................................... 332Life Of Tires................................................... 417Light Bulbs........................................... 332, 401
Lights............................................................ 332Air Bag.................................... 107, 303, 331Automatic High Beam.................................. 52Brake Assist Warning............................... 277Brake Warning.......................................... 107Bulb Replacement.................................... 401Cab Top Clearance................................... 405Cargo........................................................... 54Center Mounted Stop............................... 405Courtesy/Reading....................................... 55Cruise....................................................... 115Daytime Running......................................... 51Electronic Stability Program(ESP) Indicator............................................... 108Exterior...............................................50, 332Fog........................................................... 404Four Wheel Drive Indicator....................... 162Hazard Warning Flasher........................... 334Headlights............................................ 50, 52High Beam................................................... 51Hill Descent Control Indicator................... 278Illuminated Entry......................................... 56Interior......................................................... 55Lights On Reminder..................................... 53Low Fuel................................................... 111Malfunction Indicator (Check Engine)....... 110Park.......................................................... 115Passing........................................................ 52
Seat Belt Reminder.................................. 107Security Alarm.......................................... 108Service...................................................... 401Traction Control........................................ 277Transfer Case........................................... 162Turn Signals..................... 54, 115, 332, 402Warning Instrument Cluster Descriptions................................ 108, 115Limited-Slip Differential....................... 162, 391Load Shed Battery Saver Mode..................... 105Load Shed Battery Saver On......................... 105Load Shed Electrical Load Reduction........... 105Load Shed Intelligent Battery Sensor............ 105Loading Vehicle............................................. 199Tires.......................................................... 411LocksAutomatic Door............................................28Child Protection...........................................28Power Door..................................................25Low Tire Pressure System............................. 284Lubrication, Body.......................................... 380Lug Nuts/Bolts..................................... 342, 432
M
Maintenance Free Battery............................ 366Maintenance Plan......................................... 359Maintenance Schedule............... 353, 357, 359Malfunction Indicator Light (Check Engine).. 110

21_DPF_OM_EN_USC_t.book Page 454

456 Power Steering Fluid
...................................... 444Pregnant Women And Seat Belts...................300Preparation For Jacking................................. 339Presets.......................................................... 253PTO (Power Take-Off)..................................... 163
R
Radial Ply Tires.............................................. 416Radiator Cap (Coolant Pressure Cap).. 384, 385Radio Presets...................................................... 253Radio Controls............................................... 247Radio Mode................................................... 247Radio Operation.................................. 247, 269Radio Remote Controls.................................. 247Rain Sensitive Wiper System........................... 58Rear Axle (Differential)......................... 390, 391Rear Camera................................................. 189Rear ParkSense System................................ 177Rear Window, Sliding....................................... 78Recreational Towing...................................... 214Shifting Into Transfer Case Neutral (N)..... 216Shifting Out Of Transfer Case Neutral (N).. 217Reformulated Gasoline.................................. 433Refrigerant.................................................... 372Release, Hood................................................. 79Reminder, Seat Belt...................................... 294Remote Keyless Entry...................................... 15Programming Additional Key Fobs.............. 17Remote Sound System (Radio) Control......... 247
Remote Start (Diesel)...................................... 22Remote Start (Gasoline).................................. 20Remote StartingExit Remote Start Mode.............................. 21Replacement Bulbs...................................... 401Replacement Tires........................................ 417Reporting Safety Defects.............................. 447Resetting Perform Service Indicator............. 358Restraints, Child........................................... 312Restraints, Head.............................................. 38Rotation, Tires.............................................. 424
S
Safety........................................................... 246Safety Checks Inside Vehicle........................ 330Safety Checks Outside Vehicle..................... 332Safety Defects, Reporting............................. 447Safety Features............................................. 246Safety Information, Tire................................ 406Safety Tips.................................................... 330Safety, Exhaust Gas...................................... 333Satellite Radio.............................................. 249Saved Radio Stations................................... 253Schedule, Maintenance................................ 353Seat BeltAutomatic Locking Retractor (ALR)........... 301Seat Belt Reminder....................................... 107Seat Belts............................................ 293, 330Adjustable Shoulder Belt.......................... 297
Adjustable Upper Shoulder Anchorage..... 297Adjustable Upper Shoulder Belt Anchorage............................................ 297Child Restraints........................................ 312Extender................................................... 299Front Seat........................................ 293, 296Inspection................................................. 330Lap/Shoulder Belt Operation.................... 296Lap/Shoulder Belt Untwisting................... 297Operating Instructions.............................. 296Pregnant Women...................................... 300Reminder.................................................. 294Seat Belt Extender.................................... 299Seat Belt Reminder.................................. 294Untwisting Procedure................................ 297Seat Belts Maintenance................................ 429Seats.................................................. 33, 34, 35Adjustment...........................................33, 35Easy Entry....................................................36Folding Floor................................................70Head Restraints...........................................38Memory.......................................................32Power...........................................................35Rear Folding................................................33Tilting...........................................................33Security Alarm........................................ 23, 108Selection Of Coolant (Antifreeze).................. 440Sentry Key (Immobilizer)..................................17Service Assistance........................................ 445Service Contract............................................ 446

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