Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P258E: Power Take-Off (PTO) Enable Switch PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Mode Select A | P251A | P251A | P251A | P258E, P251A |
Mode Select B | P251A | P251A | P251A | P258E, P251A |
Mode Select C | P251A | P251A | P251A | P258E, P251A |
Circuit/System Description
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 using either the PTO switch or PTO remote, the engine RPM will increase to a default standby speed. The engine control module (ECM) converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. When PTO is engaged, the power take-off module (PTOM) sends a GMLAN serial data message to the ECM requesting engine speeds, in accordance with the depressed switches from the PTO switch or remote.
Conditions for Running the DTC
The PTO module becomes active.
Conditions for Setting the DTC
| • | The PTOM detects a valid stuck signal on one or more of the PTO switch circuits: SET -, RES +, 1 or 0. |
| • | The above condition is present for greater than 90 seconds. |
Action Taken When the DTC Sets
| • | The PTOM stores the DTC information into memory when this diagnostic runs and fails. |
| • | PTO becomes disabled until the next ignition cycle. |
Conditions for Clearing the DTC
| • | A last test failed, or the current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if failure is no longer present. |
Reference Information
Schematic Reference
Power Take-Off (PTO) Schematics
Connector End View Reference
Description and Operation
Power Take-Off (PTO) Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Engine ON, press 1 on the PTO switch to engage PTO. The PTO indicator will illuminate. The engine RPM should increase to the programmed PTO standby speed (between 800 RPM-1500 RPM) within a few seconds. Press RES + to increase the engine speed and SET - to decrease the engine speed accordingly. Press 0 to disengage PTO and to return the engine speed back to normal idle.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the in-cab PTO switch.
- Ignition ON, test for 4.5 to 5.2 volts on the vehicle harness connector between the following terminals:
- Ignition OFF, test for less than 0.5 ohm of resistance between the ground circuit terminal 5 and ground.
- If the circuits test normal, replace the PTO switch.
| • | 2 and ground |
| • | 9 and ground |
| • | 4 and ground |
| • | 1 and ground |
| ⇒ | If less than the specified range, disconnect the harness connector at the PTO module and test the failed signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PTO switch. |
| ⇒ | If greater than the specified range, test the failed signal circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module. |
| ⇒ | If greater than the specified value, test the ground circuit terminal 5 for a high resistance. If the circuit tests normal, replace the PTO module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for PTO module replacement, setup, and programming |
