Circuit Description
When cold weather conditions are detected, the engine control module (ECM) requests, from the transmission control module (TCM), the neutral lock turbine (NLT) feature. The transmission applies 3,5 and Reverse clutch and 2, 6 clutch, in conjunction with Low & Reverse clutch already applied to lock turbine shaft. This feature is only active in combination when engine elevated idle is active to shorten engine and cab warm up time.
This feature is initiated if transmission sump temperature is greater than -25°C (-13°F) and the engine coolant temperature (ECT) is greater than -40°C (-40°F). If the transmission sump temperature is greater than 60°C (140°F) or the engine coolant temperature is greater than 60°C (140°F), the NLT feature will terminate.
If the TCM detects a number of turbine slip events when the NLT feature is active, DTC P0894 will set.
DTC P0894 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0894 Transmission Component Slipping
Conditions for Running the DTC
| • | No DTCs are active. |
| • | The components are powered and ignition voltage is greater than 9-volts and less than 18-volts. |
| • | The engine speed is greater than 200 RPM but less than 7,500 RPM for 5 seconds. |
| • | NLT is attained. |
Conditions for Setting the DTC
DTC P0894 is set for this ignition cycle if the number of NLT slip events is equal to or greater than 3 or the turbine speed is greater than 50 RPM for 3 seconds.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator light (MIL) on the second consecutive occurrence. |
| • | The NLT function is disabled. |
| • | DTC P0894 is stored in TCM history. |
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Pressure switch codes, in conjunction with DTC P0894, may indicate incorrect fluid level. |
| • | Clutch test mode should be used to check stall speed in second, third, and fifth range while monitoring turbine speed for slippage. |
| • | Inspect for incorrect ECT and/or transmission sump temperature. |
| • | You may have to drive the vehicle in second, third, or fifth range in order to experience a condition. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 | Measure the transmission fluid level. Refer to Transmission Fluid Check . Is the transmission fluid level correct? | -- | Go to Step 3 | Go to Transmission Fluid Check |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Is the voltage within the specified value? | 9-18 V | Go to Step 4 | Go to DTC P0562 for low voltage or DTC P0563 for high voltage | |
4 |
Is speed sensor data erratic? | -- | Go to the appropriate speed sensor DTC | Go to Step 5 |
|
Notice: Refer to Transmission Stall Test Notice in the Preface section. Conduct a clutch test for second, third, and fifth range. Refer to Clutch Test . Did turbine speed remain at zero? | -- | Go to Diagnostic Aids | Go to Step 6 | |
6 |
Is the fluid contaminated or excessive material found in the pan? | -- | Go to Step 7 | Go to Step 8 |
7 | Remove the transmission for overhaul or replacement. Refer to Transmission Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
8 | Inspect for a stuck or sticking pressure control valve. Refer to Control Valve Body Cleaning and Inspection . Did you find and repair a valve condition? | -- | Go to Step 10 | Go to Step 9 |
9 | Replace pressure control solenoids PCS1 and PCS2. Did you complete the replacement? | -- | Go to Step 10 | -- |
10 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 11 | -- |
11 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display and DTCs that you have not diagnosed? | -- | System OK | |
