P1572, P1573 Brake Pedal Stuck ON/OFF

Step by step diagnose for DTC:
- P1572 Brake pedal stuck ON
- P1573 Brake pedal stuck OFF

The Powertrian Control Module (PCM) monitors the vehicle braking using the stop/brake lamp switch. For accuracy, the PCM monitors two separate brake switch signals. The operating mode of these signals are as follows:

P1572


Brake Signal 1 operation: The PCM sends out a 12 volt, low amperage signal, which may not illuminate a test light, on the Brake signal 1 circuit. The PCM monitors the voltage on this circuit to indicate if the brake pedal is depressed or released. The brake signal is normally closed through the stop/brake lamp switch. When the brake pedal is released, the Brake signal 1 circuit is connected to the ground circuit and the PCM reads 0.0 volts on the Brake signal 1 circuit. When the pedal is pressed, the path to ground is opened and the PCM reads 12 volts on the Brake signal 1 circuit.

Brake signal 2 operation: 12 volts are sent on the ignition switch start/run circuit through the stop/brake lamp switch to the PCM on the Brake signal 2 circuit. The PCM monitors the voltage on this circuit to indicate if the brake pedal is depressed or released. No voltage on the brake signal 2 circuit indicates to the PCM that the pedal is depressed, and 12.0 Volts indicate that the brake pedal is released.

When monitored with the ignition on during in plant testing, the brake switch is tested to verify that both switches behave correctly. Set condition the Powertrain Control Module (PCM) recognizes the brake pedal could not electrically indicate the not applied (OFF) position with both switch inputs. Default actions is ETC light will illuminate.

Possible causes:
- Brake switch out of adjustment or improperly installed
- Brake switch
- Powertrain Control Module (PCM)

Diagnostic Test P1572, P1573 code

Step 1. Check the brake switch installation
This diagnostic is used for in-plant testing only to verify that both switches behave correctly. Check the brake switch for installation and adjusment.

Is the Brake switch installed properly?

Yes, go to step 2.
No, install the brake switch correctly. Erase the DTC, if the DTC will not clear, go to Perform the Powertrain verification test.

Step 2. Replace the brake switch
Replace the brake switch, turn the ignition on. Operate the braka switch, with the scan tool read DTCs.

Is the DTC active or pending?

Yes, go to step 3.
No, Perform the Powertrain verification test.

Step 3.  Check related PCM and component connections

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