Code is P0573, which is "Brake switch circuit 1, high voltage ECM". I searched and couldn't find anything on this topic. What should I do? On the way to the shop, cruise control didn't work, on the way home after the code was cleared, it worked and yesterday it worked. What should I do? Replace the brake light switch?

 

It could be the brake position sensor (or it's calibration), the stop lamp switch or trouble in the ECM. The cruise control won't work when there is a problem with the brake pedal postion sensor because the cruise control is programmed to shut off on a brake pedal press.

Here's a segment from the service manual.


DTC P0573
Circuit Description
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The brake pedal position sensor receives a low reference signal and a 5-volt reference voltage from the body control module (BCM) when the driver applies the brakes. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop/turn signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The BCM also sends a brake pedal position sensor signal to the engine control module (ECM) as well as a serial data message to indicate the application of the brake pedal.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0573 Brake Switch Circuit 1 High Voltage

Conditions for Running the DTC
The ignition is in the ON position.
Battery voltage greater than 11.5 volts.
Conditions for Setting the DTC
The ECM detects an open or short to voltage on the signal circuit when the serial data message from the BCM indicates the brake are applied.

Action Taken When the DTC Sets
The ECM stores the DTC to memory.
The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists.
You issue a scan tool CLEAR DTCs command.
A history DTC will clear once 40 malfunction-free ignition cycles have occurred.
Diagnostic Aids

Important
Verify that the brake pedal position sensor is properly calibrated. Refer to Brake Pedal Position Sensor Calibration .
Test drive the vehicle if a switch or circuit condition cannot be located. An intermittent condition may be duplicated during a test drive.
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
Test the stop lamp switch signal circuit for an open or short to battery voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 5
Go to Step 3

3
Inspect for poor connections at the engine control module (ECM) harness connector. 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 5
Go to Step 4

4
Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the repair?
Go to Step 5
--

5
Use a scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK

 

Thanks! Sounds like a faulty brake light switch to me...but my brake lights work fine...I also hear an audible 3-4 clicks when I step on the brakes upon first getting into the car so that would tell me the brake switch is fine right? Cruise works...it just didnt for a drive, then worked again. Does this all fit in your opinion?