P0894

DTC P0894

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 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

* The ignition voltage is between 9-18 V.
* Engine speed is greater than 200 RPM for 5 seconds.
* NLT is commanded on.

Conditions for Setting the DTC

The TCM detects turbine speed greater than 50 RPM for 3 seconds. This condition must occur 3 times.

Action Taken When the DTC Sets

* DTC P0894 is a Type B DTC.
* The neutral locked turbine function is disabled.

Conditions for Clearing the DTC

DTC P0894 is a Type B DTC.

Diagnostic Aids

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

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Allison - Automatic Transmission)
Connector End View Reference

* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)

Description and Operation

* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description)

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)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

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

Circuit/System Verification

1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
2. Perform the Road Test (Allison - Automatic Transmission).
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 (Line Pressure Check).

• If line pressure is low in all ranges, refer to Low Main Line Pressure in All Ranges (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 (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.

2. Perform the clutch test. Refer to Clutch Test (Clutch Test).

• If not the specified value, refer to Excessive Slippage and Clutch Chatter (Excessive Slippage and Clutch Chatter).

Repair Verification

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