Circuit Description
The stop lamp switch indicates the brake pedal status to the transmission control module (TCM). The brake switch is a normally-closed switch that supplies battery voltage on the stop lamp relay control voltage circuit to the TCM. Applying the brake opens the stop lamp switch, interrupting voltage to the TCM. When the brake is released, the TCM receives a constant voltage signal input. If the TCM receives a zero voltage signal input at the stop lamp relay control voltage circuit, and the torque converter clutch (TCC) is engaged, the TCM de-energizes the TCC solenoid valve. The TCM disregards the brake switch input for TCC scheduling if there is a brake switch circuit fault.
When the TCM detects a closed brake switch circuit, battery voltage, high input, during decelerations, DTC P0724 will set. 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
| • | DTCs P0722 or P0723 must not be set as current. |
| • | DTC P0719 must not be set as current. |
| • | The vehicle speed is greater than 40 km/h (25 mph) for 7 seconds then vehicle speed is less than 40 km/h (25 mph), but greater than 8 km/h (5 mph) for less than 4.75 seconds. |
Conditions for Setting the DTC
The TCM detects voltage on the stop lamp switch signal circuit during vehicle acceleration.
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 present when the Conditions for Setting the DTC are met. The TCM records this information as a failure record. |
| • | The TCM stores DTC P0724 to memory. |
Conditions for Clearing the DTC
| • | You issue a scan tool CLEAR DTCs command. |
| • | A history DTC will clear once 40 malfunction-free ignition cycles have occurred. |
Diagnostic Aids
| • | Verify that the brake pedal position sensor is properly calibrated. Refer to Brake Pedal Position Sensor Calibration . |
| • | Applying the brake pedal during vehicle acceleration may cause DTC P0724 to set. |
| • | Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 | Are the brake lamps stuck ON? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | ||||||
3 |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 7 | ||||||
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 8 | ||||||
5 | Locate and repair an short to battery voltage in the stop lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 6 | ||||||
6 | Inspect for poor connections at the harness connector of the transmission control module (TCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 | ||||||
7 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 | ||||||
8 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11 | ||||||
9 | 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 12 | -- | ||||||
10 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | -- | ||||||
11 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | -- | ||||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | System OK | Go to Step 2 | ||||||
