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 engine speed input that is below the lower limit, above the upper limit, or is an unreliable value, then DTC P0727 will set. DTC P0727 is a type B DTC.
Condition for Running the DTC
The ignition is ON.
Condition for Setting the DTC
Engine speed input is below the lower limit, above the upper limit, or is an unreliable value for 4.0 seconds.
Action Taken When the DTC Sets
| • | The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL. |
| • | The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM. |
| • | The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts). |
Conditions For Clearing the MIL/DTC
| • | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request. |
| • | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic. |
| • | The scan tool clears the MIL/DTC. |
| • | The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM. |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | |||||||||
2 |
Important: Record all Failure Records before clearing the DTC. Using Clear Info erases the Failure Records from the ECM and TCM. Did you record any ECM Failure Records? | -- | Go to the applicable ECM DTC | |||||||||
3 | Did you record Failure Records for any of the following DTCs?
| -- | Go to the applicable CAN Bus DTC | |||||||||
4 |
Is the Engine Speed value within the specified range? | 500-1000 RPM | ||||||||||
5 | Road test the vehicle for at least five minutes using various engine speeds. Did P0727 reset? | -- | Go to Intermittent Conditions in Engine Controls | |||||||||
6 |
Is the Engine Speed value within the specified range? | 500-1000 RPM | ||||||||||
7 | Did any other DTCs set? | -- | Go to the applicable DTC | |||||||||
8 | Replace the ECM. Refer to Engine Control Module Replacement . Is the action complete? | -- | -- | |||||||||
9 | Perform the following operation to verify the repair:
Did DTC P0727 reset? | -- | System OK |
