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 P0894: Transmission Component Slipping

Circuit/System Description

When the engine controller requests the neutral locked turbine (NLT) feature, the transmission control module (TCM) commands the 3rd, 5th and reverse clutch and the 2-6 clutch to apply, which locks the turbine shaft. This provides a load to the engine and reduces the engine warm up time.

Conditions for Running the DTC

    • Components are powered and the ignition voltage is greater than 9 V and less than 18 V.
    • Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
    • NLT is attained.

Conditions for Setting the DTC

The DTC sets when the TCM detects 3 accumulative events with turbine speed greater than 50 RPM for 3 seconds.

Action Taken When the DTC Sets

    • The neutral locked turbine function is disabled.
    • The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) on the second consecutive occurrence.
    • DTC P0894 is stored in TCM history.

Conditions for Clearing the DTC

DTC P0894 is a Type B DTC.

Diagnostic Aids

    • Shift solenoid valve performance codes, in conjunction with P0894, may indicate incorrect fluid level.
    • Incorrect gear ratio codes may indicate clutch damage.

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. Inspect the transmission fluid level. Refer to Transmission Fluid Check.
  2. Perform a road test. Refer to Road Test.
  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. Perform a line pressure test. Refer to Line Pressure Check.
  2. If line pressure is low in all ranges, refer to Low Main Line Pressure in All Ranges.
    If line pressure is low in a specific range or ranges, refer to Low Main Line Pressure in Specific Ranges, Normal Pressure in Other Ranges.

    Warning: Chock the wheels to prevent the vehicle from moving. Failure to chock the wheels can cause personal injury when the electrical system is repaired.

  3. Perform the clutch test. Refer to Clutch Test.
  4. If not the specified value, refer to Excessive Slippage and Clutch Chatter.

Repair Verification

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