GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Sierra Denali 🢒 Transmission 🢒 Automatic Transmission - Allison 🢒 DTC P0561

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 P0561: System Voltage Performance

Circuit/System Description

The transmission control module (TCM) requires a switched ignition voltage input to operate. The TCM continuously monitors the ignition voltage.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Condition 1

DTC sets when the TCM detects ignition voltage below 6.5 V for 1 second.

Condition 2

DTC sets when the TCM detects a variation in ignition voltage greater than 4 V for a number of samples within 1 second.

Action Taken When the DTC Sets
    • The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
    • DTC P0561 is stored in TCM history.

Conditions for Clearing the DTC

DTC P0561 is a Type C DTC.

Diagnostic Aids
    • A defective vehicle battery may allow this code to set.
    • A defective vehicle charging system may allow this code to set.
    • You may have to drive the vehicle in order to experience a condition.
    • Although this DTC could indicate an internal voltage condition within the TCM, in most cases, the TCM is not at fault. Investigate thoroughly prior to replacing the TCM.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Transmission General Description
    •  Transmission Component and System Description
    •  Electronic Component Description

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The reading should be between 12.6 and 15 V.
    2. ⇒If not the expected value, refer to Battery Charging.
  2. Observe the scan tool TCM ignition voltage parameter. The reading should be between 12.6 and 15 V.
  3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

    Note: You must perform the Circuit/System Testing first.

  1. Ignition OFF, disconnect the harness connector at the TCM.
  2. Ignition OFF, test for less than 3 ohms between ground circuit terminal 9 and battery ground, and also ground circuit terminal 69 and battery ground.
    3. ⇒If greater than the specified range, repair the affected ground circuit.
  3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 63 and ground.
    4. ⇒If the test lamp does not illuminate, repair the ignition circuit.
    ⇒If circuit tests normal, replace the TCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TCM replacement, setup, and programming.

Repair Verification

If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.