For 1990-2009 cars

### Circuit Description

Brake switch 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 P0703 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P0703.

When the PCM sends the TCM an invalid brake switch signal, then DTC P0703 will set. DTC P0703 is a type C DTC.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0703 Brake Switch Circuit

### Conditions for Running the DTC

• | No CAN DTC U0100.

• | Trans. Protection Mode OFF.

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

### Conditions for Setting the DTC

The brake switch signal is invalid for 4 seconds.

### Action Taken When the DTC Sets

• | The TCM commands the brake signal off.

• | 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 TCM stores DTC P0703 in TCM history.

### Conditions for Clearing the SVS Lamp/DTC

• | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-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 | 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 the ignition ON, 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 ECM Failure Records?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3 |

1. Clear the DTC.
2. Turn the ignition OFF for at least 30 seconds.
3. Start, and allow the engine to idle.

Did DTC P0703 reset?

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections

4 | Did any other DTCs set? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 5
5 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Is the action complete? | Go to Step 6 | --
6 | Perform the following operation to verify the repair:

1. Select DTC on the scan tool.
2. Select Clear Info.
3. Start the engine and vary the throttle.
4. Select Specific DTC.
5. Enter DTC P0703.

Does the DTC reset?

Go to Step 2

Go to Step 7

7 | 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