P159C

DTC P159C

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P159C
- Power Take-Off (PTO) Remote Engine Shutdown Switch Circuit

Diagnostic Fault Information





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 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 engine is running and PTO is engaged.

Conditions for Setting the DTC

* The PTOM detects a signal mismatch between the remote engine shut off signal and the PTO engine shutdown signal.
* The above condition is present for greater than a predetermined time threshold.

Action Taken When the DTC Sets

* The PTOM stores the DTC information into memory when this diagnostic runs and fails.
* The malfunction indicator lamp (MIL) will not illuminate.
* PTO becomes disabled until the next ignition cycle.
* The remote engine start function defaults back to disabled.

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 100 consecutive warm-up cycles, if failure is no longer present.

Reference Information
Schematic Reference

Power Take-Off (PTO) Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Power Take-Off (PTO) Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Verification

With PTO enabled, use a scan tool to shutdown the engine using the Engine Shutdown special function in the PTO module. The engine should shutdown.

Circuit/System Testing

1. Engine ON, verify that the PTO Remote Switch Status parameter reads PTO On when the upfitted PTO remote engine switch is commanded ON and reads PTO Off when the upfitted PTO remote engine shutdown switch is commanded OFF.

• If the parameter does not read the specified values accordingly, test the engine shut off signal circuit terminal 31 for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, test or replace the upfitted remote engine shutdown switch.

2. If the DTC still sets as current, replace the PTO module.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Control Module References) for PTO module replacement, setup, and programming