P0504

DTC P0504: Brake Switch Circuit 1 - 2 Correlation

Wiring Diagram:

Circuit Description
Brake lamp switch is a normally open switch that closes when the brake pedal is depressed. When the brake pedal is depressed, the bake lamp switch supplies signal voltage to the brake lamp switch signal circuit. Brake pedal switch is a normally closed switch that opens when the brake pedal is depressed.

The Engine Control Module (ECM) monitors the brake lamp switch signal circuit and the brake pedal switch signal circuit. The ECM monitors the status of the brake lamp switch signal circuit and the brake pedal switch signal circuit to see if they match when the brake pedal is pressed or released.

Conditions for Setting the DTC
- Engine is running.
- If time from state change of one brake input to when the other brake input changes state (making switch states equal again) is greater than 0.5 seconds, fail counts increase by 3. When the fail counts reach 39, this DTC sets.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after four consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
- Inspect for proper adjustment of the stop lamp switch.
- Check for internments and poor connections.

Step 1-9:

Step 10-18:

Troubleshooting