Circuit Description
Engine speed information is sent to the transmission control module (TCM) by the engine control module (ECM) through the controller area network (CAN). A 2-wire circuit is used to communicate data between the ECM and TCM, CAN H and CAN L. A fault in the CAN will not cause DTC P0727 to set by itself. If a communication fault occurs, other DTCs will set before P0727.
When the ECM sends the TCM an invalid engine speed, DTC P0727 sets. DTC P0727 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0727 Engine Speed No Signal
Conditions for Running the DTC
| • | No HSCAN DTC U0100. |
| • | The engine is running for 5 seconds and not in fuel cut-off. |
Conditions for Setting the DTC
The engine speed is invalid for 1 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM calculates a default engine speed based on transmission input shaft speed. |
| • | The TCM freezes transmission adaptive functions. |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records. |
| • | 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 DTC default actions when the ignition switch is OFF long enough in order to power down the TCM. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Important:
Did you record any ECM Failure Records? | -- | Go to Step 3 | |||||
3 | Did you record a TCM Failure Record for DTC U0100? | -- | Go to DTC U0100-U0299 | 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 set again? | -- | Go to Step 7 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
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 Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 8 | ||||
8 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Is the action complete? | -- | Go to Step 9 | -- | ||||
9 | Perform the following procedure to verify the repair:
Has the test run and passed? | -- | Go to Step 10 | Go to Step 2 | ||||
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? | -- | System OK |
