Orlando

DTC P0504 - AT

The engine control module (ECM) monitors the brake light switch signal circuit and the cruise control release signal circuit every 100 ms. The ECM monitors the status of the brake light switch signal circuit and the cruise control signal circuit to see if they match when the brake pedal is pressed or released.

The status of the brake light switch input to the ECM and the cruise/brake switch input to the ECM do not match for at least 2 s continuously, for 10 occurrences. Each time the signals match, then do not match at counter increments. When the counter reaches 10, this DTC will set.

When DTC P0504 00 is set, the following will occur:

Schematic Reference

Exterior Lamps Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the function of the brake lights while applying and releasing the brake pedal. The brake lights should turn ON and OFF as the brake pedal is applied and released.

⇒	If the brake lights are always ON or always OFF, refer to Stop Lamps Malfunction .

2. Observe the scan tool Brake Pedal Switch parameter while applying and releasing the brake pedal. The parameter should change from Active to Inactive.

1. Ignition OFF, disconnect the harness connector at the B22 Brake Pedal Position Sensor.
2. Ignition ON, verify that a test lamp illuminates between B+ and the low reference circuit terminal A.

⇒	If the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal C and ground.

⇒	If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

⇒	If less than the specified range, test the 5 V reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

4. Ignition OFF, reconnect harness connector at the B22 Brake Pedal Position Sensor.
5. Ignition ON, test for B+ between the harness connector terminals listed below and ground:

•	With 2H0, K20 Engine Control Module harness connector terminal 58 X1

•	With LNP, K20 Engine Control Module harness connector terminal 178 X1

•	With MH7 or MH8, K71 Transmission Control Module harness connector terminal 10 X1

⇒	If less than the specified range, test the brake signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

⇒	If within the specified range, test the brake signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

6. Verify that DTC P0571 00 is not set.

⇒	If DTC P0571 00 is set, replace the K20 Engine Control Module. Clear the DTC and road test the vehicle. If the DTC resets, replace the K9 Body Control Module.

7. If all circuits test normal, test or replace the B22 Brake Pedal Position Sensor or K71 Transmission Control Module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.