DTC P0504-2B: Brake Switch "A"/"B" Signal Cross Coupled [12/2023 - ]: Description
WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.
The stop light switch assembly is a duplex system that transmits signal: ST1-. The semiconductor power integration ECU transmits signal: STP. These two signals are used by the hybrid vehicle control ECU assembly to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed and released, are detected simultaneously, the hybrid vehicle control ECU assembly interprets this as a malfunction in the stop light switch assembly, semiconductor power integration ECU and stores this DTC.
HINT:
The normal signal conditions are as shown in the table below.
| Signal (hybrid vehicle control ECU assembly Terminal) | Brake Pedal Released | In Transition | Brake Pedal Depressed |
|---|---|---|---|
| STP | OFF | ON | ON |
| ST1- | ON | ON | OFF |
- [OFF] denotes ground potential.
- [ON] denotes battery potential (+B).
On the GTS, Data List item Stop Light SW is ON when the brake pedal is depressed.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Warning Indicate | DTC Output from | Priority | Note |
|---|---|---|---|---|---|---|---|---|
| P0504-2B | Brake Switch "A"/"B" Signal Cross Coupled | Conditions (a) and (b) are met for 0.5 seconds or more (1 trip detection logic): (a) Ignition switch ON (b) STP signal OFF when ST1- signal OFF |
|
Does not come on | Master Warning: Does not come on |
Hybrid Control | A | SAE Code: P0504 |