Circuit Description
The stop lamp switch indicates brake pedal status to the transmission control module (TCM). The normally-open stop lamp switch supplies ignition voltage to the TCM. Applying the brake pedal closes the switch, supplying voltage to the TCM. Releasing the brake pedal interrupts voltage to the TCM. When the TCM senses ignition voltage at the stop lamp switch input, the TCM de-energizes the torque converter clutch (TCC) solenoid valve.
When the TCM detects a closed stop lamp switch, stuck ON, during accelerations, 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 VSS DTCs P0722 or P0723.
Conditions for Setting the DTC
DTC P0724 sets if the TCM detects a closed stop lamp switch or circuit, 12 volts, for 15 minutes and the following conditions occur eight times:
- The vehicle speed is less than 8 km/h (5 mph);
- then, the vehicle speed is 8-32 km/h (5-20 mph) for 2-6 seconds;
- then, the vehicle speed is greater than 32 km/h (20 mph) for 6 seconds.
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 stores this information as Failure Records. |
| • | The TCM stores DTC P0724 in TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear 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. |
| • | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Disconnecting the stop lamp switch connector, and observing a status change, isolates the stop lamp switch as the source of the DTC.
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This step inspects the signal circuit for a short to voltage, if the stop lamp switch status on the scan tool did not change in Step 2.
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If the stop lamp switch is properly adjusted, then the stop lamp switch must be replaced.
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Replace the TCM only after you have completed the preceding diagnostic steps.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||
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. Does the Brake Switch status change from Closed to Open? | Go to Step 4 | Go to Step 3 | |||||
Test the signal circuit of the stop lamp switch for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 | |||||
Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the replacement? | Go to Step 6 | -- | |||||
Replace the TCM. Refer to Control Module References in Computer/Integrating Systems 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? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
