Circuit Description
The stop lamp switch is used to sense the action of the driver application of the brake pedal. The stop lamp switch is a normally open switch that, when applied, provides a B+ analog voltage to the transmission control module (TCM).
When the TCM detects a closed stop lamp switch circuit, B+ voltage, during a calibrated number of accelerations, then DTC P0724 sets. DTC P0724 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0724 Brake Switch Circuit High Voltage
Conditions for Running the DTC
| • | No OSS DTCs P0722 or P0723. |
| • | No Brake Switch DTC P0719. |
| • | The vehicle speed is less than 40 km/h (25 mph) for 6 seconds, then greater than 40 km/h (25 mph) for 7 seconds, then less than 8 km/h (5 mph). |
Conditions for Setting the DTC
DTC P0724 sets when the TCM detects the brake switch circuit is open during accelerations.
Action Taken When the DTC Sets
| • | The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM records this information as a Failure Record. |
| • | The TCM stores DTC P0724 in TCM history. |
Conditions for Clearing the 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. |
| • | A scan tool can clear the DTC. |
Diagnostic Aids
| • | Inspect the brake switch for proper mounting and operation. |
| • | Inspect for ABS DTCs. A faulty ABS condition may contribute to setting DTC P0724. |
| • | It may be necessary to also clear this DTC from the ECM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the TCM. Caution: Refer to SIR Caution in the Preface section. Did the Brake Switch status on the scan tool change from Closed to Open? | Go to Step 3 | Go to Step 4 | |
3 | Replace the brake switch. Refer to Stop Lamp Switch Replacement . Did you complete the replacement? | Go to Step 6 | -- |
4 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics for complete circuit distribution. Test the signal circuit of the brake switch for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 7 | Go to Step 2 |
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? | System OK |
