P0724

VT25-E AUTOMATIC TRANSMISSION

DTC P0724

Test 1-7:

Circuit Description with VT25-E Automatic Transmission
The stop lamp switch is used to indicate the status of the brake switch, applied or released, to the transmission control module (TCM). The normally-closed stop lamp switch supplies an ignition voltage input to the TCM. Applying the brake pedal allows the switch to close, thereby applying a voltage to the TCM. Releasing the pedal pushes the brake plunger in and opens the switch, thus interrupting the voltage to the TCM. When the TCM senses ignition voltage at the stop lamp switch input, the TCM de-energizes the TCC pressure control solenoid valve.

If the TCM detects a closed stop lamp switch, stuck ON, during accelerations, the DTC P0724 sets. DTC P0724 is a type C DTC.

Conditions for Running the DTC
No OSS DTCs P0722 or P0723.

Conditions for Setting the DTC
The stop lamp switch input detects ignition voltage for 15 minutes and the following conditions occur 8 times without a status change on the stop lamp switch input:
^ The output shaft speed is less than 400 RPM, then;
^ The output shaft speed is between 400 RPM and 1,400 RPM for 3 seconds, then;
^ The output shaft speed is greater than 1,400 RPM for 6 seconds.

Action Taken When the DTC Sets
^ The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
^ SERVICE VEHICLE message displays on the driver information center (DIC).
^ The TCM defaults to the Controller Area Network brake switch or a calculated brake switch based on the output speed sensor, and the throttle position sensor.
^ 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 P0724 in TCM history.

Conditions for Clearing the DIC/DTC
^ The TCM clears the DIC message when the condition no longer exists.
^ A scan tool can clear the DIC/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 DTC default actions when the fault no longer exists and the DTC passes.

Diagnostic Aids
^ Inspect the connectors at the TCM, the stop lamp switch, and all other circuit connecting points for an intermittent condition.
^ Inspect the circuit wiring for an intermittent condition.

Test Description
The numbers refer to the step numbers on the diagnostic table.
2. Disconnecting the brake switch connector, and observing a status change, isolates the brake switch as the source of the DTC.
3. This step tests the signal circuit for a short to voltage, if the brake switch status on the scan tool did not change in Step 2.
4. If the brake switch is properly adjusted, then the brake switch must be replaced.
5. Replace the TCM only after you have completed the preceding diagnostic steps.