Brand:

Toyota

Model Name:

Yaris NCP90 91 92 93

Manual:

Repair Manual

Section:

1Nz-Fe Engine Control System

Title:

Sfi System

  1. Description

  2. Wiring diagram

  3. Inspection procedure

  4. Check stop light switch assembly (terminal voltage)

  5. Inspect stop light switch assembly

  6. Check ecm (stp and st1 - voltage)

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


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DESCRIPTION

The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two 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 an intelligent tester.

Signals
Brake Pedal Released
In Transition
Brake Pedal Depressed
STP
OFF
ON
ON
ST1-
ON
ON
OFF

DTC No.
DTC Detection conditions
Trouble Areas
P0504
Conditions (a), (b) and (c) continue for 0.5 seconds or more
(1 trip detection logic):
(a) ignition switch to ON
(b) Brake pedal released
(c) STP signal OFF when ST1- signal OFF
  1. Short in stop light switch signal circuit
  2. Stop light switch
  3. STOP fuse
  4. IGN fuse
  5. ECM

WIRING DIAGRAM


Read freeze frame data using an intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred. Yaris


Read freeze frame data using an intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred. Yaris


INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT:
  1. Read freeze frame data using an intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
  2. STP signal conditions can be checked using an intelligent tester.
    1. Connect an intelligent tester to the DLC3.
    2. Turn the ignition switch to ON and turn the tester on.
    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch.
    4. Check the STP signal when the brake pedal is depressed and released.

      Brake Pedal Operation
      		Specified Conditions
      Depressed
      		STP signal ON
      Released
      		STP signal OFF
1.CHECK STOP LIGHT SWITCH ASSEMBLY (TERMINAL VOLTAGE)
Disconnect the stop light switch connector. Yaris

  1. Disconnect the stop light switch connector.

  1. Turn the ignition switch to ON.

  1. Measure the voltage according to the value(s) in the table below.

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A13-2 - Body ground
    		Ignition switch ON
    		11 to 14 V
    A13-3 - Body ground
    		Ignition switch ON
    		11 to 14 V

  1. Reconnect the stop light switch connector.



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REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
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2.INSPECT STOP LIGHT SWITCH ASSEMBLY
Remove the stop light switch assembly. Yaris

  1. Remove the stop light switch assembly.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Switch Position
    		Specified Condition
    1 - 2
    		Switch pin released
    		Below 1 Ω
    Switch pin pushed in
    		10 kΩ or higher
    3 - 4
    		Switch pin released
    		10 kΩ or higher
    Switch pin pushed in
    		Below 1 Ω

  1. Reinstall the stop light switch assembly.



NGnext
REPLACE STOP LIGHT SWITCH ASSEMBLY (Click here)
OK
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3.CHECK ECM (STP AND ST1 - VOLTAGE)
Disconnect the ECM connector. Yaris

  1. Disconnect the ECM connector.

  1. Turn the ignition switch to ON.

  1. Measure the voltage according to the value(s) in the table below.

Standard Voltage:
Tester Connection
Brake Pedal Operation
Specified Condition
A21-35 (ST1-) - Body ground
Released
11 to 14 V
Depressed
Below 1.5 V
A21-36 (STP ) - Body ground
Released
Below 1.5 V
Depressed
11 to 14 V

  1. Reconnect the ECM connector.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
next down
REPLACE ECM (Click here)