The power take-off (PTO) is an upfitter integrated system that allows the user to create an auxiliary power source. The PTO system specifically controls engine speed to values higher than normal base idle, PTO load relay engagement, and remote starting and shutdown of the engine. When the operator requests PTO, the PTO switch will be turned ON and the engine RPM will go to a default standby speed.

The PTO system utilizes the following:

Factory Installed PTO Components

In-cab PTO Switch

The PTO switch is mounted in the right side of the center instrument panel. The PTO switch is a four position rocker type: 1, 0, SET - and RES +. When the PTO 1 position is depressed, the PTO relay will be energized by the PTOM. A PTO LED indicator is integrated with the switch. The indicator will illuminate, flashing at a 0.25 second interval rate when the PTO relay is energized. The indicator illuminates solid once the PTO load feedback signal confirms the load has been engaged or after 3 seconds if load feedback is not utilized by the PTO system. The indicator will flash at a 1 second interval rate when PTO memory speed is retained. Depressing the 0 position turns the PTO system off. The PTO LED will turn off once engine speed reaches base engine idle, at which time the PTO relay is de-energized.

Transmission Driven PTO Gear

The Allison LCT-1000 transmission provides the PTO gear with the vehicles PTO option package. If the vehicle option package does not include PTO, then the PTO gear will not be included in the transmission.

The illumination of the background text of the PTO switch is provided through the dimming circuit controlled by the BCM.

Power Take-Off Module (PTOM)

The PTO electrical system is integrated around a central PTO control module. The PTO Module (PTOM) provides the following key functions:

The PTOM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance. If any of the PTO engage conditions for the specific operating mode are no longer valid, the engine controller will exit out of PTO mode.

Remote PTO Upfitter Connector

The PTO upfitter connector provides access to all remote PTO functions. The connector is located on the right-hand outside frame rail, underneath the passenger side door. Electrical connections to the following components are provided by this connector. The upfitter connector pin circuits (other than battery, ignition and ground) are disabled as the vehicle is received from the factory. The PTO module must be reprogrammed by the upfitter or dealer to enable the following circuits:

The PTO system also utilizes the following vehicle modules, which communicate over the serial data system:

Body Control Module (BCM)

The BCM maintains the PTO factory default mode, unless it is reprogrammed with a scan tool to change the PTO configuration mode from factory preset to either stationary variable or mobile variable. The BCM also controls the remote start function. The BCM also controls the illumination of the background text of the PTO switch through the dimming circuit.

Electronic Brake Control Module

The EBCM monitors the vehicle speed. The PTOM receives the status of the vehicle speed from the EBCM via serial data messages.

Engine Control Module (ECM)

The ECM controls the engine speed and the engine starting based on messages from the PTOM through serial data. The ECM also provides PTO specific engine information to the PTOM through serial data messages.

Instrument Panel Cluster (IPC)

The driver information center (DIC) of the IPC displays actions the driver must take in order to engage PTO. If the PTO will not engage, one or more of the following DIC messages may appear on the instrument panel cluster (IPC):

Transmission Control Module (TCM)

The TCM adjusts shift patterns to minimize shift during PTO operation. The TCM also provides transmission gear states and temperature conditions to the PTOM via serial data messages.

Stationary PTO

The following conditions must be met in order to engage stationary PTO:

In-cab PTO operation: Press and release the 1 position on the PTO switch. The PTO LED will flash fast until the PTO load becomes engaged. When the load becomes engaged, the LED will stop flashing and stay illuminated. The SET - and RES + switch positions can then be used to establish the desired PTO operating speed.

Remote PTO operation: Press and release the remote PTO arming switch, then within five seconds, move the PTO enabled switch from OFF to ON. The remote LED will illuminate when the PTO load is engaged. The PTO remote SET switch can then be used to establish the desired PTO operating speed. These switches are accessed through the PTO upfitter connector, located under the passenger side door.

Mobile PTO

The following conditions must be met prior to engaging mobile PTO:

Stationary PTO

The stationary PTO mode will disengage if any of the following conditions are detected by the vehicle modules:

Mobile PTO

The mobile PTO mode will also disengage if the following conditions are detected by the vehicle modules:

The PTO control system will attempt to limit accelerator pedal and PTO switch input as the vehicle approaches the above operational limits. There are some vehicle conditions, such as down hill acceleration, which may cause vehicle speed or engine speed limits to be exceeded. Under those conditions, PTO is disengaged.

Preset PTO Mode

Preset PTO can only be used when the vehicle is not moving. The engine speed is initially set to a standby engine speed of 800 RPM. This provides an initial start-up engine speed to match the engagement of the PTO load. The PTO standby engine speed can be reprogrammed to higher speeds.

Choose one of two presets by pressing and releasing the PTO In-cab or remote PTO SET in the SET - or RES + switch positions:

Pressing the 0 switch position on the PTO in-cab switch or moving the remote PTO enable switch to OFF results in the return of the engine speed back to normal idle. The PTO load relay is also disengaged.

Maximum PTO Operating Speed: During PTO operation, the accelerator pedal can be pressed to adjust the engine speed. To protect the PTO from overspeed, the PTO system will disengage when the engine speed exceeds 2100 RPM.

The Stationary PTO Mode provides both in-cab and remote controls. The in-cab controls are enabled as the factory preset. The remote controls are disabled. This factory preset configuration can be reprogrammed to enable the remote controls, and disable the in-cab PTO controls.

PTO - Variable Mode

In this mode, the vehicle can be programmed for stationary or mobile operation.

The variable PTO mode controls engine speed and PTO load engagement is selected by either the PTO in-cab or remote switches. Engine speed selection is variable between base engine idle speed and a maximum of 2100 RPM.

In the mobile PTO mode, the vehicle will operate at a vehicle speed resulting from the current PTO engine speed request and current transmission gear range selected.

Vehicle speed stability is greatly improved by shifting into the transmission manual mode because upshifts are limited. This reduces the maximum vehicle speed while allowing high engine speed operation. Therefore, low vehicle speed operation, 16-40 km/h (10-25 mph) and high PTO engine speed 1500-2000 RPM can be achieved in the manual mode 1 and 2 transmission ranges.

In-cab PTO Switch Operation:

The PTO system allows the engine to be remotely started while operating in the stationary PTO mode. The wiring system provides for connections to a remote engine start arming switch and remote starting switch. These connections are accessed through the upfitter connector.

The remote start function is initiated by a sequence of switch actions, in addition to several vehicle conditions. The following conditions must be met before attempting to remote start the engine. The vehicle ignition key can be in any position or removed from the ignition:

Once the above conditions are met, to continue with the remote start, use the remote PTO controls to do the following:

1. Press and release the remote start arming switch.
2. Within five seconds of releasing the remote start arming switch, press and hold the remote engine start switch for about two seconds until the engine starts. Release the remote engine start switch.

To enable normal PTO operation following a remote start event, with PTO remote enable switch in the OFF position, press and release the arming switch. Then within five seconds, the PTO remote enable switch must be toggled to ON. The PTO system will then elevate engine RPM to standby speed and engage the PTO load. Press the remote PTO SET - or RES + switches to elevate PTO to the desired engine operating speed.

The PTO system allows for remote engine shutdown while operating the stationary PTO mode. This feature has the following functions:

A scan tool must be used to enable certain PTO options and also to adjust the factory preset parameters to the desired settings. The scan tool menu driven device is a hand held scan tool that plugs into the datalink connector located underneath the dash near the driver seat.

For additional scan tool information, refer to Control Module References.