Duramax Diesel. Manual - part 19

Driving and Operating

engage and the PTO indicator
light will change to solid. The
engine speed will advance to
the PTO Standby Speed.

6. The desired operating speed

may be achieved by tapping up
and down with +RES and SET
− on the cruise control.

The PTO load relay engages
immediately when the PTO
operation is initiated by the
switch input. The transmission
torque converter is unlocked.
The torque converter will lock
upon reaching stable PTO
Standby Speed (default = 900
rpm) so maximum power is
available.

The first elevated engine speed,
PTO Standby Speed, is not
intended as a working speed but
as a verification that the system
is active and ready to go to a
working speed.

The relay connections are made
at the PTO Upfitter Connector
located on the chassis frame
behind the cab.

The engine speeds can be
adjusted between the low of
PTO Standby Speed and the
high of PTO Max Engine speed
limits. Both values can be
modified from the factory default
settings with the GM Service
Tool. Based on the value chosen
for PTO Max Engine Speed, the
PTO menu in the center stack
may show speeds that are not
available.

Factory setting for the tap step is
100 rpm and the setting for ramp
rate is 150 rpm/sec. The default
value for tap step can be
modified via the Radio
Customization menu. The
default values for both tap step
and ramp rate can be changed
with the GM Service Tool.

The PTO load relay is enabled
as the factory default
programmed setting.

Refer to the service manual or
go to the GM Upfitter Integration
website www.gmupfitter.com for
details.

Mobile PTO

Mobile Enable Conditions –
In-Cab Operation Only

This requires programming with the
GM Service Tool.

1. The engine must be running.

2. The parking brake must be

released.

3. Confirm that cruise control

is off.

4. Engine rpm must be less than

1500 rpm.

5. Shift the transmission to M1,

M2, or M3.

6. Tap the brake pedal and then

do not press the brake pedal.

7. Keep the driver door closed.

The driver door can be kept
open if reconfigured using the
GM Service Tool. See
www.gmupfitter.com.

8. Press and release the PTO

in-cab switch below the climate
controls in the center stack.
Then within 10 seconds press
and release +RES on the

Driving and Operating

cruise control. The PTO
indicator light will blink slowly
between presses. The PTO
indicator light will then blink
rapidly until the PTO load
becomes engaged, and then
come on steady. The engine
speed will remain at the current
throttle setting or advance to
PTO Standby Speed,
whichever value is greater.
If the engine rpm is above
1500 rpm, the PTO relay will
not engage until the engine
rpm drops below 1500 rpm.

9. Once engaged, if additional

engine speed is desired, use
either the cruise control or the
accelerator pedal to temporarily
adjust the engine speed.

‐ +RES on the cruise control

can be used to tap up, or if
continuously held to ramp
up, to the desired operating
speed. SET− on the cruise
control can be used to tap
down or coast down if
continuously held to the
desired engine speed. Top
limit is PTO Max Engine

Speed, default 2100 rpm and
programmable to 2900 rpm.
Lower limit is PTO Standby
Speed, default 900 rpm with
program range from base
idle to 900 rpm.

‐ The accelerator pedal can be

used to achieve the desired
speed. When the desired
speed is reached, SET− on
the cruise control would be
used to capture and maintain
that speed. Normal tap up
and tap down can then be
used to fine tune the setting.

In Mobile PTO mode, the vehicle
speed achieved is the result of the
current engine speed requested and
the transmission gear range
selected. When the vehicle is
placed in M2 or M3, the vehicle will
upshift according to engine rpm set
point, and vehicle speed will
increase. To prevent upshifts and
maintain lower vehicle speeds,
place the vehicle in M1.

Mobile Enable Conditions –
Operator Selectable In-Cab
Mode (OSIM)

This requires programming with the
GM Service Tool and specific
pairing mobile mode with either
stationary preset or variable.
Remote operation is not available.

See “Mobile PTO” previously in this
section.

PTO System Disengage
Conditions

Preset or Variable Stationary
Modes – In-Cab Operation

To disengage PTO, do one of the
following:
.

Press the brake pedal. 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. Upon
releasing the brake, the factory
default programming is for the
engine speed to remain at curb
idle. A press and release of
+RES on the cruise control will

Driving and Operating

restore engine rpm to the last
PTO set speed. The PTO
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. Activating
+RES on the cruise control will
restore engine rpm to the last
PTO set speed.

Press and release the PTO
in-cab switch. The PTO 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.

Stationary Modes (Preset or
Variable) – Remote Control

To disengage PTO:
.

Open the Remote PTO Engine
Start/Shutdown switch. Load
relay disengages and the engine
will stop.

If equipped, press the PTO
Emergency Stop switch. Load
relay disengages and the engine
will stop. Refer to the bulletins in
the Upfitter Integration website
www.gmupfitter.com for the
Power Take Off (PTO) operating
description and application
guide.

With the key in the ignition and
rotated to the RUN position,
press the brake pedal. The PTO
load relay disengages and the
engine returns to base idle
speed. The operator may drive
the vehicle.

Stationary Modes will also
disengage if:
.

Vehicle movement is detected.

The parking brake is released.

The transmission is shifted out
of P (Park).

The ignition is cycled from RUN
to OFF.

The PTO feedback signal is lost
indicating the load is disengaged
if used. See
www.gmupfitter.com.

Cruise control becomes enabled.

Timed auto-engine shutdown:
This feature will shut down the
engine automatically after a
predefined time. PTO must be
operational for this function to be
active.

Engine shutdown based on
critical engine or PTO system
fault conditions: This feature will
shut down the engine when PTO
is operating if a critical engine
condition such as low oil, low oil
pressure, hot engine, hot
transmission, low fuel, or Diesel
Particulate Filter regeneration is
detected by the vehicle system.
If PTO operation is continued
when critical engine conditions
are present, a horn chirp

Driving and Operating

warning will occur after 30–
60 seconds. The engine will shut
down two minutes after the horn
warning. The engine can be
restarted with the ignition key or
with the Remote PTO engine
start controls. The horn warning
and engine shutdown will again
occur if the critical engine
condition is still present.

Resume memory speed is cleared
for the above actions.

When Remote PTO engine starting
has been initialized with the ignition
key in the RUN position, the shift
lever will remain locked if the brake
pedal is pressed and a shift from
P (Park) is attempted while the
engine is running and PTO is active
(standby mode). A shift out of
P (Park) will not be allowed until one
of the following actions is taken by
the vehicle operator:
.

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.

Press

on 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.

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