DTC P0504 Brake Switch "A" / "B" Correlation: Description
The stop light switch is a duplex system that transmits 2 signals: STP and ST1-. These 2 signals are used by the ECM 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 ECM interprets this as a malfunction in the stop light switch and sets the DTC.
HINT:
The normal conditions are as shown in the table below. The signals can be read using the intelligent tester.
BRAKE SWITCH CONDITION
| Signal | Brake Pedal Released | In Transition | Brake Pedal Depressed |
|---|---|---|---|
| STP | OFF | ON | ON |
| ST1- | ON | ON | OFF |
DTC TROUBLE DETECTION CONDITION
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0504 | Conditions (a), (b) and (c) continue for 0.5 seconds or more (1 trip detection logic):
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