P253D
DTC P253D
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 P253D
- Power Take-Off (PTO) Relay Feedback Circuit High Voltage
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 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 and PTO is engaged.
Conditions for Setting the DTC
* The PTOM detects a high voltage signal at the PTO engage signal circuit.
* The above condition is present continuously 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.
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 ([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
Engine ON, press 1 on the PTO switch to engage PTO. The engine RPM should increase to the default engine speed within a few seconds. Press RES + to increase the engine speed and SET - to decrease the engine speed accordingly.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the PTO module.
2. Ignition OFF, disconnect the PTO relay.
3. Ignition ON, verify that a test lamp does not illuminate between the PTO engage signal circuit terminal 46 and ground.
• If the test lamp illuminates, test the PTO engage signal circuit for a short to voltage. If the circuit tests normal, test or replace the upfitted remote engine PTO switch assembly.
4. Ignition OFF, connect the harness connector at the PTO module.
5. Ignition ON, verify that a test lamp does not illuminate between the PTO engage signal circuit terminal 46 and ground.
• If the test lamp illuminates, replace the PTO module.
6. If all circuits test normal, test or replace the PTO relay.
Component Testing
PTO Relay (If supported by the PTO upfitter wiring)
1. Ignition OFF, disconnect the PTO relay.
2. Test for approximately 50-200 ohms of resistance between terminals H and J on the upfitter wiring side of the upfitter PTO connector.
• If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* F and J
* F and H
* F and K
* K and J
• If less than infinite resistance, replace the PTO relay.
4. Install a 15-amp fused jumper wire between relay terminal J and 12 volts. Install a jumper wire between relay terminal H and ground. Test for less than 2.0 ohms of resistance between the relay switch terminals.
• If greater than 2.0 ohms, replace the PTO relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Control Module References)for PTO module or TCM replacement, setup, and programming