P0504

DTC P0504: Brake Switch "A"/"B" Correlation

Wiring Diagram










DTC Detecting Condition and Trouble Area






DTC Confirmation Procedure

1) With ignition switch turned OFF, connect scan tool to DLC.
2) Turn ON ignition switch and clear DTC.
3) Start engine and warm up to normal operating temperature.
4) Drive vehicle at 50 km/h (31 mph) or higher for 3 min. or more.
5) Stop vehicle.
6) Depress brake pedal for 3 times.
7) Check DTC.

DTC Troubleshooting

NOTE:

Before performing the above-mentioned trouble shooting, read and observe Precautions for DTC Troubleshooting Precautions for DTC Troubleshooting.

1. Brake light switch check

Check brake light switch referring to Testing and Inspection Brake Light Switch On-Vehicle Inspection.

Is it in good condition?
YES -
Go to Step 2.
NO -
Replace brake light switch.

2. Brake light switch power circuit check

Disconnect connector from brake light switch connector with ignition switch turned OFF.
Check for proper connection to switch connector.
If connection are OK, measure voltage between each "BLU/BLK" wire terminal and "GRN" wire terminal of brake light switch connector and vehicle body ground with ignition switch turned ON.

Is each measured voltage 10 - 14 V?
YES -
Go to Step 3.
NO -
Check related fuse and repair defective circuit.

3. Brake light switch signal circuit check

Disconnect connectors from ECM with ignition switch turned OFF.
Check for proper connection of each switch circuit terminal to ECM connector.
If connections are OK, check brake light switch circuit for the following.
- Resistance of each "YEL/GRN" wire terminal and "GRN/YEL" wire terminal (with brake light relay) or "GRN/WHT" wire terminal (without brake light relay) of brake light switch between brake light switch connector and ECM connector is less than 1 ohms (continuity check)
- Resistance between "YEL/GRN" wire terminal and "GRN/YEL" wire terminal (with brake light relay) or "GRN/WHT" wire terminal (without brake light relay) of brake light switch connector are infinity (no continuity check)
- Resistance between each "YEL/GRN" wire terminal and "GRN/YEL" wire terminal (with brake light relay) or "GRN/WHT" wire terminal (without brake light relay) of brake light switch connector and vehicle body ground is infinity (ground short check)
- Voltage of between each "YEL/GRN" wire terminal and "GRN/YEL" wire terminal (with brake light relay) or "GRN/WHT" wire terminal (without brake light relay) of brake light switch connector and vehicle body ground is 0 V with ignition switch turned ON (power short check)

Is it in good condition?
YES -
Substitute a known-good ECM and recheck.
NO -
Repair or replace defective wire.