## DTC Troubleshooting: P0504 (159)

DTC P0504: | Brake Pedal Position Switch Circuit Malfunction

1. | Turn the ignition switch ON (II).

2. | Check the BRAKE SWITCH B in the DATA LIST with the HDS when the brake pedal pressed. Is OFF indicated? YES - Go to 3. NO - Check the brake pedal position switch, then go to 28.

3. | Check the BRAKE SWITCH in the DATA LIST with the HDS when the brake pedal pressed. Is ON indicated? YES - Go to 4. NO - Go to 7.

4. | Release the brake pedal.

5. | Check the BRAKE SWITCH B in the DATA LIST with the HDS when the brake pedal pressed. Is ON indicated? YES - Go to 6. NO - Go to 19.

6. | Check the BRAKE SWITCH in the DATA LIST with the HDS when the brake pedal pressed. Is OFF indicated? YES - Intermittent failure, system is OK at this time.Check for poor connections or loose terminals at the brake pedal position switch and the ECM.n NO - Check the brake pedal position switch, then go to 28.

7. | Check the brake lights. Do the brake lights come on? YES - Go to 8. NO - Go to 12.

8. | Turn the ignition switch OFF, and wait 10 seconds.

9. | Connect the ECM test harness and the test pin box to the wire harness only, not to the ECM.

10. | Disconnect the brake pedal position switch 4P connector.

11. | Check for continuity between test pin box terminal No. 117 and the brake pedal position switch 4P connector terminal No. 2. Is there continuity? YES - Go to 34. NO - Repair open in the wire between the ECM connector No. 4 terminal No. 36 (test pin box terminal No. 117) and the brake pedal position switch, then go to 28.

12. | Turn the ignition switch OFF.

13. | Disconnect the brake pedal position switch 4P connector.

14. | Measure voltage between brake pedal position switch 4P connector terminal No. 1 and body ground. Is there battery voltage? YES - Go to 16. NO - Go to 15.

15. | Check the No. 16 (10 A) fuse in the under-hood fuse/relay box. Is the fuse OK? YES - Repair open in the wire between the brake pedal position switch and the No. 16 (10 A) fuse, then go to 28. NO - Replace the No. 16 (10 A) fuse in the under-hood fuse/relay box, then go to 28. Repair short in the wire between the brake pedal position switch and the No. 16 (10 A) fuse, then go to 28.

16. | Connect the ECM test harness and the test pin box to the wire harness only, not to the ECM.

17. | Check for continuity between test pin box terminal No. 117 and body ground. Is there continuity? YES - Repair short in the wire between the ECM connector No. 4 terminal No. 36 (test pin box terminal No. 117) and the brake pedal position switch, then go to 28. NO - Go to 18.

18. | Check the brake pedal position switch. Is the brake pedal position switch OK? YES - Go to 34. NO - Adjust or replace the brake pedal position switch, then go to 28.

19. | Turn the ignition switch OFF.

20. | Disconnect the brake pedal position switch 4P connector.

21. | Turn the ignition switch ON (II).

22. | Measure voltage between brake pedal position switch 4P connector terminal No. 3 and body ground. Is there battery voltage? YES - Go to 24. NO - Go to 23.

23. | Check the No. 5 (7.5 A) fuse in the under-dash fuse/relay box. Is the fuse OK? YES - Repair open in the wire between the brake pedal position switch and the No. 5 (7.5 A) fuse, then go to 28. NO - Replace the No. 5 (7.5 A) fuse in the under-dash fuse/relay box, then go to 28. Repair short in the wire between the brake pedal position switch and the No. 5 (7.5 A) fuse, then go to 28. Repair short in the wire between the ECM connector No. 4 terminal No. 22 (test pin box terminal No. 103) and the brake pedal position switch, then go to 28.

24. | Turn the ignition switch OFF, and wait 10 seconds.

25. | Connect the ECM test harness and the test pin box to the wire harness only, not to the ECM.

26. | Check for continuity between test pin box terminal No. 103 and brake pedal position switch 4P connector terminal No. 4. Is there continuity? YES - Go to 27. NO - Repair open in the wire between the ECM connector No. 4 terminal No. 22 (test pin box terminal No. 103) and the brake pedal position switch, then go to 28.

27. | Check the brake pedal position switch. Is the brake pedal position switch OK? YES - Go to 34. NO - Adjust or replace the brake pedal position switch, then go to 28.

28. | Turn the ignition switch OFF.

29. | Reconnect all connectors.

30. | Turn the ignition switch ON (II).

31. | Reset the ECM with the HDS.

32. | Do the ETCS learn procedure.

33. | Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS. Are any Temporary DTCs or DTCs indicated? YES - If DTC P0504 is indicated, check for poor connections or loose terminals at the brake pedal position switch and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting. NO - Troubleshooting is complete.n

34. | Substitute a known-good ECM.

35. | Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS. Are any Temporary DTCs or DTCs indicated? YES - If DTC P0504 is indicated, check for poor connections or loose terminals at the brake pedal position switch and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting. NO - Replace the original ECM.n