For 1990-2009 cars

### Circuit Description

Engine speed information is sent to the transmission control module (TCM) by the powertrain control module (PCM) through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the PCM 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 PCM sends the TCM an invalid engine speed, then DTC P0727 will set. DTC P0727 is a type A DTC.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0727 Engine Speed No Signal

### Conditions for Running the DTC

• | No CAN DTC U0100.

• | The system voltage is 8-18 volts.

• | Trans. Protection Mode is OFF.

• | The ignition has been ON for at least 3 seconds.

### Conditions for Setting the DTC

The engine speed is invalid for 4 seconds.

### Action Taken When the DTC Sets

• | The TCM requests the PCM to illuminate the malfunction indicator lamp (MIL).

• | The TCM turns Trans. Protection Mode ON.

• | 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 PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as a Freeze Frame.

• | The TCM stores DTC P0727 in TCM history.

### Conditions for Clearing the MIL/DTC

• | The PCM 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 - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.

Important:

• | Before clearing the DTC, use the scan tool in order to record the PCM Freeze Frame and the TCM Failure Records. Using the Clear Eng./Trans. DTC Info function erases the Freeze Frame and Failure Records from the powertrain control module (PCM) and the transmission control module (TCM).

• | Using the Clear Eng./Trans. DTC Info function erases stored DTCs in both the PCM and TCM.

3. Record the DTC Failure Records.

Did you record any PCM Failure Records?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3 | Did you record a TCM Failure Record for DTC U2105? | -- | Go to U2105 | Go to Step 4
4 |

1. Clear the DTC.
2. Turn the ignition OFF for at least 30 seconds.
3. Start and idle the engine.
4. Observe the Engine Speed on the scan tool.

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 Testing for Intermittent Conditions and Poor Connections
6 |

1. Select Engine Data on the scan tool.
2. Observe the scan tool Engine Speed parameter.

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 - Vehicle | Go to Step 8
8 | Replace the PCM. 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:

1. Select DTC on the scan tool.
2. Select Clear Info.
3. Turn ON the ignition, with the engine OFF.
4. Operate the engine at varying speeds.
5. Select Specific DTC.
6. Enter DTC P0727.

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 - Vehicle | System OK