Circuit Description
Engine speed information is sent to the transmission control module (TCM) by the engine control module (ECM) through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the ECM and TCM. A fault in the CAN will not cause DTC P0727 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P0727.
When the ECM sends the TCM an invalid engine speed, then DTC P0727 will set. DTC P0727 is a type A DTC.
Conditions for Running the DTC
| • | No CAN DTC U2105. |
| • | The system voltage is 8-18 volts. |
| • | Trans. Protection Mode is OFF. |
| • | The ignition has been ON for at least 3.0 seconds. |
Conditions for Setting the DTC
The engine speed is invalid for 4.0 seconds.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL). |
| • | The TCM turns Trans. Protection Mode ON. When Trans. Protection Mode is ON, the following conditions occur: |
| - | The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range. |
| - | The line pressure is at maximum. |
| - | The torque converter clutch (TCC) is disabled. |
| - | The TCM freezes the transmission adaptive functions. |
| • | Limit engine torque to 270 N·m (200 lb ft). |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
| • | The TCM stores DTC P0727 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 3.0L (L81) | ||||
2 |
Important:
Did you record any ECM Failure Records? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.0L (L81) | Go to Step 3 | ||||
3 | Did you record a TCM Failure Record for DTC U2105? | -- | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | Go to Step 4 | ||||
4 |
Is the Engine Speed within the specified range? | 500-1,000 RPM | Go to Step 5 | Go to Step 6 | ||||
5 | Road test the vehicle using various engine speeds. Did DTC P0727 reset? | -- | Go to Step 7 | Go to Intermittent Conditions in Engine Controls - 3.0L (L81) | ||||
6 |
Is the Engine Speed value within the specified range? | 500-1,000 RPM | Go to Step 7 | Go to Step 8 | ||||
7 | Did any other DTCs set? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.0L (L81) | Go to Step 8 | ||||
8 | Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls - 3.0L (L81). Is the action complete? | -- | Go to Step 9 | -- | ||||
9 | Perform the following procedure to verify the repair:
Does the DTC reset? | -- | Go to Step 2 | Go to Step 10 | ||||
10 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.0L (L81) | System OK |
