DTC Troubleshooting: P0504 (159)
DTC P0504:
 Brake Pedal Position Switch Circuit Malfunction
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  1. Turn the ignition switch ON (II).
  1. Check BRAKE PEDAL POSITION SWITCH B in the DATA LIST with the HDS when the brake pedal pressed.
Is ON indicated?
YES -
Go to Step 3 .
NO -
Check the brake pedal position switch, then go to Step 29 .
  1. Check BRAKE PEDAL POSITION SWITCH A in the DATA LIST with the HDS when the brake pedal pressed.
Is ON indicated?
YES -
Go to Step 4 .
NO -
Go to Step 7 .
  1. Release the brake pedal.
  1. Check BRAKE PEDAL POSITION SWITCH B in the DATA LIST with the HDS.
Is OFF indicated?
YES -
Go to Step 6 .
NO -
Go to Step 20 .
  1. Check BRAKE PEDAL POSITION SWITCH A in the DATA LIST with the HDS.
Is OFF indicated?
YES -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the brake pedal position switch and the ECM.■
NO -
Check the brake pedal position switch, then go to Step 29 .
  1. Check the brake lights.
Do the brake lights come on?
YES -
Go to Step 8 .
NO -
Go to Step 12 .
  1. Turn the ignition switch OFF, and wait 2 minutes.
  1. Disconnect the brake pedal position switch 4P connector.
  1. Disconnect ECM connector No. 2 (58P).
  1. Check for continuity between ECM connector No. 2 terminal No. 38 and brake pedal position switch 4P connector terminal No. 2.
Is there continuity?
YES -
Go to Step 34 .
NO -
Repair open in the wire between the brake pedal position switch and ECM connector No. 2 terminal No. 38, then go to Step 29 .
  1. Turn the ignition switch OFF.
  1. Disconnect the brake pedal position switch 4P connector.