Circuit Description
The body control module (BCM) receives a signal from the brake pedal position (BPP) sensor through the brake pedal position switch signal circuit. The BCM then applies a signal through the stop lamp switch signal circuit to the transmission control module (TCM) and engine control module (ECM).
When the TCM detects voltage on the stop lamp switch signal circuit during acceleration 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 output speed sensor (OSS) DTCs P0722 or P0723. |
| • | No brake switch DTC P0719. |
| • | The vehicle speed is 8-40 km/h (5-25 mph) for 6 seconds, then greater than 40 km/h (25 mph) for 7 seconds. |
Conditions for Setting the DTC
The TCM detects voltage on the stop lamp switch signal circuit during acceleration.
Action Taken When the DTC Sets
| • | The TCM does not request the 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
Important:
• Verify that the BPP sensor is adjusted properly. Refer to Brake Pedal
Position Sensor Calibration in Lighting Systems. • Test drive the vehicle if a switch or circuit condition cannot be located.
An intermittent condition may be duplicated during a test drive. • Application of the brake pedal while accelerating may cause this DTC to
set.
Test Description
The number below refers to the step number on the diagnostic table.
-
This step determines if the fault is present.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
2 | Are the brake lamps stuck ON? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
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 | Test for the stop lamp switch signal circuit a short to voltage between the BCM, ECM and transmission control module (TCM). Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | ||||||
6 | Replace the TCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
7 | Replace the BCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
8 | Replace the ECM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 10 | Go to Step 2 | ||||||
10 | 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 |
