Chevrolet/GMC 2.8L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-14465442) - 2021 - CRC - 2/3/20
Driving and Operating 45
.Press the Remote PTO Engine Start/
Shutdown switch.
.Press the PTO in-cab switch (only if the
PTO in-cab Remote Start/Stop feature is
enabled). This requires programming with
the GM Service Tool.
.Press5on the cruise control.
.Release the parking brake.
Mobile Mode
To disengage PTO:
.Press the brake pedal. The PTO system
releases control of engine speed, but the
PTO load relay remains engaged. The
engine will return to base idle unless the
accelerator pedal is pressed. The PTO load
relay remains engaged. The PTO indicator
light will blink slowly indicating that a
PTO set speed is still stored in memory.
Upon releasing the brake, the factory
default programming is for the engine
speed to remain at curb idle awaiting an
input from +RES on the cruise control to
restore engine rpm to the last PTO set
speed. The system can also be
programmed to return engine rpm to the
PTO Standby Speed setting.
.Press*on the cruise control. The engine
returns to base idle, but the PTO load
relay remains engaged. The PTO indicator
light will blink slowly indicating that a
PTO set speed is still stored in memory.
Pressing +RES on the cruise control will
restore engine rpm to the last PTO set
speed.
.Press the PTO in-cab switch. Load relay
disengages and the engine returns to
base idle. The PTO indicator light will turn
off, indicating the PTO load relay is
disengaged and the stored set speed has
been cleared from memory.
Mobile Mode will also disengage if:
.PTO feedback input is lost. The engine
speed is returned to the PTO Standby
speed setting and the load is still
engaged. This is configurable with the GM
Service Tool.
.Vehicle Speed exceeds Max Vehicle Speed.
Factory default setting = 94 km/h
(58 mph). PTO relay will re-engage and
advance to the last engine speed stored
in memory when both the Vehicle Speed
is reduced below 94 km/h (58 mph) and
the engine speed ramps down below the
maximum PTO engagement speed (1500
rpm factory default setting).
.Engine Speed exceeds Max Engine Speed
for more than 15 seconds. Factory default
setting = 2100 rpm.
.5on the cruise control is pressed.
.The parking brake is applied.
.The shift lever is moved out of manual
shift selection, M1, M2, or M3.
Resume memory speed is cleared for the
above actions.
Although the PTO system attempts to limit
accelerator and PTO switch inputs to comply
with maximum speed and/or rpm
parameters, some vehicle operating
conditions such as downhill acceleration can
cause the vehicle speed or engine rpm to
exceed these limits. In those cases, the PTO
system may disengage.
Operator Selectable In-Cab Mode (OSIM)
To disable OSIM Stationary PTO:
.Press and release the PTO in-cab switch.
To disable OSIM Mobile PTO:
.Press and release the PTO in-cab switch.
Prolonged or Extended PTO Operation
When operating the vehicle in stationary
PTO mode, the Diesel Particulate Filter (DPF)
will continue to filter the exhaust and
Chevrolet/GMC 2.8L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-14465442) - 2021 - CRC - 2/3/20
62 Vehicle Care
Warning (Continued)
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
If no coolant is visible in the surge tank, add
coolant as follows:
2.8L 4-Cylinder Van Pressure Cap
1. Remove the coolant surge tank pressure cap when the cooling system, including
the coolant surge tank pressure cap and
upper radiator hose, is no longer hot.
Turn the pressure cap slowly
counterclockwise about one full turn. If a
hiss is heard, wait for that to stop.
A hiss means there is still some
pressure left.
2. Keep turning the pressure cap slowly, and remove it. 3. Slowly fill the coolant surge tank. Do not
let the coolant level go above the
indicated mark in the tank until after the
engine comes to operating temperature
in Step 4.
4. With the coolant surge tank pressure cap off, start the engine and let it run until
the engine coolant temperature gauge
indicates approximately 90 °C (195 °F).
By this time, the coolant level inside the
coolant surge tank may be lower. If the
level is lower, slowly add more of the
proper mixture to the coolant surge tank
until it reaches the indicated mark.
5. Re-install the pressure cap. Be sure the pressure cap is hand-tight
and fully seated.
6. Verify coolant level after the engine is shut off and the coolant is cold.
If necessary, repeat Steps 1–6.
If the coolant level is still low after having
followed these steps twice, have the coolant
system checked by a certified technician at
the dealer for a possible leak.
Caution
If the pressure cap is not tightly installed,
coolant loss and engine damage may
occur. Be sure the cap is properly and
tightly secured.
Engine Overheating
There is an engine coolant temperature
gauge on the instrument cluster. See the
owner’s manual.
If Steam Is Coming from the Engine
Compartment
{Warning
Steam and scalding liquids from a hot
cooling system are under pressure.
Turning the pressure cap, even a little,
can cause them to come out at high
speed and you could be burned. Never
turn the cap when the cooling system,
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
Chevrolet/GMC 2.8L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-14465442) - 2021 - CRC - 2/3/20
66 Vehicle Care
The vehicle may not be equipped with all of
the fuses, relays, and features shown.Fuses Usage
F1 Traction control module power
F2 Engine control module power
F3 Air conditioning clutch
F4 NOx sensors/Exhaust particulate sensors
F5 Engine control module/ Integrated chassis control
module/Water in fuel
sensor
F6 Front wipers F7 Cargo lamp/Bed lighting
F8 Engine control module miscellaneous
F9 Engine control module
F10 Engine control mod- ule-injectors
F11 Mass airflow sensor
F12 Starter
F13 Traction control module Fuses
Usage
F14 –
F15 –
F16 –
F17 Front axle actuator
F18 –
F19 –
F20 Fuel pump F21 Front blower
F22 Antilock brake system valves
F23 –
F24 Trailer F25 Transfer case electronic control
F26 Antilock brake system pump
F27 Trailer brake control module
F28 Rear window defogger
F29 –
F30 Driver heated seat Fuses
Usage
F31 –
F32 Passenger heated seat
F33 Body control module 3
F34 Integrated chassis control module
F35 –
F36 Center high-mounted stoplamp
F37 Right high-beam headlamp
F38 Left high-beam headlamp
F39 Rear differential lock actuators
F40 Front differential lock actuators/Selective catalytic
reduction power module
wake up
F41 Glow plug module
F42 –
F43 –
F44 Fuel heater F45 Selective catalytic reduction power module heater
Chevrolet/GMC 2.8L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-14465442) - 2021 - CRC - 2/3/20
Vehicle Care 67
FusesUsage
F46 Cooling fan clutch F47 Heater crankcase ventilation
F48 Fog lamps
F49 Selective catalytic reduction power module wake up
F50 Trailer parking lamps F51 Horn
F52 –
F53 –
F54 –
F55 –
F56 Washer pump F57 –
F58 –
F59 –
F60 Mirror defogger F61 –
F62 Selective catalytic reduction power module
F63 – Fuses
Usage
F64 Trailer reverse lamps F65 Left trailer stoplamp/ Turnlamp
F66 Right trailer stoplamp/ Turnlamp
F67 Electric power steering
F68 –
F69 Battery regulated voltage control
F70 –
F71 –
F72 –
F73 –
F74 Generator F75 –
Relays Usage
K1 Air conditioning clutch
K2 Starter
K3 Powertrain sensor
K4 Wiper speed Relays
Usage
K5 Wiper control
K6 Cargo lamp/Bed lighting K7 Powertrain
K8 Fuel pump
K9 Front differential lock actuators
K10 Rear differential lock actuators
K11 Center high-mounted stoplamp
K12 Fuel heater
K13 Selective catalytic reduction power
module heater control/
Diesel exhaust fluid
control
K14 Trailer parking lamps K15 Run/Crank
K16 Cooling fan clutch K17 Rear window defogger/ Mirror defogger
Chevrolet/GMC 2.8L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-14465442) - 2021 - CRC - 2/3/20
Vehicle Care 69
The vehicle may not be equipped with all of
the fuses, relays, and features shown.Fuses Usage
1 Antilock brake system motor
2 Antilock brake system module
3 Right trailer stoplamp/ Turnlamp
4 –
5 –
6 Fuel system control module/Ignition
7 Body control module 5
8 Body control module 7
9 Body control module 4
10 Instrument cluster 11 Trailer wiring
12 –
13 Display/Mirrors/Rear vision camera
14 Washer
16 Horn Fuses Usage
17 Transmission
18 Air conditioning
19 Engine control module battery
20 Left stop/turn cutaway lamp
21 Left stop/turn trailer lamp
22 Right stop/turn cutaway lamp
23 NOx sensors
24 Diesel fuel pump 25 Auxiliary power outlet
26 Body control module 3 27 Special equipment option
28 Airbag
29 Steering wheel sensor
30 Engine control module/ Glow plug module/
Ignition Fuses Usage
31 Transmission control module/Ignition
32 Transmission control module battery
33 Obstacle detection
34 NOx sensors 35 Fuel operated heater module
36 Fuel system control module battery
41 Transmission control module 2, battery
signal
42 Trailer wiring
43 EV fan clutch
44 Starter solenoid 45 Engine control module, powertrain signal 1
46 DC-AC inverter 47 Cooling fan –low
51 Left high-beam headlamp