GM Service Manual Online
For 1990-2009 cars only

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 P260D 00: Power Take-Off (PTO) Engaged Indicator Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

PTO Switch Indicator Control

P260D 00

P260D 00

P260D 00

P260D 00

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 ignition is ON.

Conditions for Setting the DTC

    • The PTOM detects an invalid voltage signal at the PTO switch indicator control circuit.
    • The above condition is present continuously for greater than a predetermined time threshold.

Action Taken When the DTC Sets

    • The ECM stores the DTC information into memory when this diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
    • 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 failures are not reported by this or any other emission related diagnostic.

Reference Information

Schematic Reference

    •  Power Take-Off (PTO) Schematics
    •  Interior Lights Dimming Schematics

Connector End View Reference

Power Take-Off (PTO) Connector End Views

Description and Operation

Power Take-Off (PTO) Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

  1. Verify that the interior backlighting system operates normal. Refer to Interior Lighting Systems Description and Operation .
  2. Engine ON, press 1 on the PTO switch to engage PTO. The PTO LED indicator will turn on blinking at a 0.25 second interval rate when the PTO relay is energized. The indicator turns on 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.

Circuit/System Testing

Important: If the interior backlighting is malfunctioning, refer to Interior Backlighting Does Not Dim or Interior Backlighting Inoperative before performing this diagnostic.

  1. Ignition OFF, disconnect the harness connector at the PTO switch.
  2. Connect a test lamp between LED dimming supply circuit terminal 7 and ground.
  3. Ignition OFF, turn the headlamps ON and OFF. The test lamp should turn ON and OFF accordingly with the headlamp switch.
  4. If the test lamp is always ON, test the LED dimming supply circuit for a short to voltage.
    If the test lamp is always OFF, test the LED dimming supply circuit for a short to ground or an open/high resistance.
  5. Ignition ON, verify that a test lamp does not illuminate between the PTO switch indicator control circuit terminal 8 and ground.
  6. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.
  7. Ignition OFF, PTO OFF, verify that a test lamp does not illuminate between the PTO switch indicator control circuit and B+.
  8. If the test lamp illuminates, test the PTO switch indicator control circuit for a short to ground. If the circuit tests normal, test or replace the PTO module.
  9. Ignition OFF, disconnect the harness connector at the PTO module.
  10. Ignition OFF, test for less than 1.0 ohm of resistance on the PTO switch indicator control circuit between the PTO switch terminal 8 and the PTO module terminal 9.
  11. If greater than the specified range, test the PTO switch indicator control circuit for an open/high resistance.
  12. If all circuits test normal, test or replace the PTO switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Take-Off Switch Replacement
    •  Control Module References for PTO module replacement, setup, and programming