GM Service Manual Online
For 1990-2009 cars only
Table 1: Engine Speed Power Take-Off Control Module Scan Tool Data Parameters
Table 2: Engine Speed Power Take-Off Control Module Scan Tool Output Controls

The scan tool data lists contain all of the power take-off (PTO) related parameters that are available on the scan tool. The parameters in the list are arranged in alphabetical order. The data list column indicates the location of the parameter within the scan tool menu selections.

Use the scan tool data lists as directed by a diagnostic table or in order to supplement the diagnostic procedures. Begin all of the diagnostic procedures with Diagnostic System Check - Vehicle.

Use the scan tool data lists only after the following is determined:

    • There is no published DTC procedure or published symptom procedure for the customer concern.
    • The DTC or symptom procedure indicated by the diagnostic system check does not resolve the customer concern.

Engine Speed Power Take-Off Control Module Scan Tool Data Parameters

Parameter

System State

Expected Value

Description

Operating Conditions: Ignition ON/Engine Idling at Normal Operating Temperature/Vehicle is in Park or Neutral/PTO Disengaged

Engine Speed

--

Varies

The scan tool displays 0 to 9,999 RPM. The engine control module (ECM) monitors the crankshaft position (CKP) signal circuit in order to determine the engine RPM.

Ignition 1 Signal

--

Varies

The scan tool displays Volts. This is the voltage at the B+ input of the PTOM.

PTO Disengage Reason

--

Last reason why PTO was disengaged

The scan tool displays the last reason why the PTO was disengaged. Refer to the Scan Tool Data Definitions (Disengage or Inhibit Reasons) for descriptions.

PTO Indicator

--

Off

The scan tool displays On or Off. The PTOM monitors the signal circuit of the PTO switch. A closed switch is displayed as On.

PTO Inhibit Reason

--

Reason why PTO is currently inhibited

The scan tool displays the last reason why the PTO system was inhibited. Refer to the Scan Tool Data Definitions (Disengage or Inhibit Reasons) for descriptions.

PTO In Cab Switch

--

PTO Off

The scan tool displays PTO Off, PTO On, Set 1, Set 2, No Action, Invalid, or Indeterminate. The PTOM monitors the signal circuit of the PTO switch.

PTO In Cab Switch A

--

Numeric

The scan tool displays %. The PTOM monitors the mode select A circuit and displays the current percentage.

PTO In Cab Switch B

--

Numeric

The scan tool displays %. The PTOM monitors the mode select B circuit and displays the current percentage.

PTO In Cab Switch C

--

Numeric

The scan tool displays %. The PTOM monitors the mode select C circuit and displays the current percentage.

PTO Option

--

Disable

The scan tool displays Enhanced, Disable, Preset, Variable, Mobile, or Fast Idle. This is the current state of the PTO system.

PTO Remote Accelerator Sensor (If Equipped)

--

Numeric

The scan tool displays %. If equipped, the ECM sends a serial data message to the PTO module regarding the status of the PTO remote accelerator sensor.

PTO Remote Switch Status

--

PTO Off

The scan tool displays PTO Off, PTO On, Set 1, Set 2, No Action, Invalid, or Indeterminate. The PTOM monitors the signal circuit of the PTO remote switch.

PTO Status

--

No

The scan tool displays Disabled, Standby Disabled, Standby Pending, PTO Standby, PTO Active, Reserved, PTO Set, PTO Coast, Reserved, PTO Accelerate, Shutdown, or No Action. This is the current status of the PTO system.

Requested Engine Speed

--

Varies

The scan tool displays the requested RPM.

Vehicle Speed

--

Varies

The scan tool displays 0 to 150 km/h (93.2 mph). The ECM monitors the vehicle speed sensor signal circuit in order to calculate the vehicle speed for display. The ECM sends a serial data message to the PTOM regarding the current vehicle speed.

Engine Speed Power Take-Off Control Module Scan Tool Output Controls

Output Control

Description

Clear PTO Reasons

The scan tool clears the PTO Disengagement and Inhibit reasons stored in the PTO module.

Engine Shutdown

The scan tool commands the PTO module to shut down the engine.

PTO Indicator

The scan tool commands the PTO module to illuminate the PTO indicator on and off.

PTO Relay

The scan tool commands the PTO module to enable and disable the PTO relay.