Toyota Avalon Service & Repair Manual: Brake Switch "A"/"B" Signal Cross Coupled (P05042B)

Toyota Avalon Service & Repair Manual / Engine / 2gr-fks Engine Control / Sfi System / Brake Switch "A"/"B" Signal Cross Coupled (P05042B)

DESCRIPTION

The stop light switch assembly 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 assembly and stores this DTC.

HINT:

The normal signal conditions are as shown in the table below.

Signal (ECM 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 Techstream, Data List item Stop Light SW is ON when the brake pedal is depressed.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P05042B

Brake Switch "A"/"B" Signal Cross Coupled

Conditions (a) and (b) are met for 0.5 seconds or more (1 trip detection logic):

(a) Engine switch on (IG)

(b) STP signal OFF when ST1- signal OFF

  • Open or short in stop light switch signal circuit
  • Stop light switch assembly
  • Instrument panel junction block assembly
  • ECM

Does not come on

DTC stored

SAE Code: P0504

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

  • Stop light switch assembly conditions can be checked using the Techstream.
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / Stop Light SW.
    5. Check the Data List indication when the brake pedal is depressed and released.

      Brake Pedal Operation

      Stop Light SW

      Depressed

      ON

      Released

      OFF

  • Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, 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.

PROCEDURE

1.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)

*a

Front view of wire harness connector

(to Stop Light Switch Assembly)

(a) Disconnect the stop light switch assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A33-7 (B) - Body ground

Always

11 to 14 V

NG

GO TO STEP 11

OK

2.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)

*a

Front view of wire harness connector

(to Stop Light Switch Assembly)

(a) Disconnect the stop light switch assembly connector.

(b) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A33-6 (B) - Body ground

Engine switch on (IG)

11 to 14 V

NG

GO TO STEP 6

OK

3.

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

(a) Disconnect the stop light switch assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A33-2 (GND) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK TERMINAL VOLTAGE (STP AND ST1- VOLTAGE)

*a

Brake Pedal Depressed

*b

Brake Pedal Released

*c

Front view of wire harness connector

(to ECM)

-

-

(a) Disconnect the ECM connector.

(b) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Brake Pedal Operation

Specified Condition

A18-42 (ST1-) - Body ground

Released

7.5 to 14 V

Depressed

Below 1.5 V

A18-27 (STP) - Body ground

Released

Below 1.5 V

Depressed

7.5 to 14 V

OK

REPLACE ECM

NG

5.

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)

(a) Disconnect the stop light switch assembly connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A33-5 (L) - A18-42 (ST1-)

Always

Below 1 Ω

A33-3 (L) - A18-27 (STP)

Always

Below 1 Ω

A33-5 (L) or A18-42 (ST1-) - Body ground and other terminals

Always

10 kΩ or higher

A33-3 (L) or A18-27 (STP) - Body ground and other terminals

Always

10 kΩ or higher

OK

REPLACE STOP LIGHT SWITCH ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY)

(a) Disconnect the instrument panel junction block assembly connector.

(b) Disconnect the stop light switch assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4F-15 - A33-6 (B)

Always

Below 1 Ω

4F-15 or A33-6 (B) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

7.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND)

(a) Disconnect the instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4D-3 - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

8.

CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (POWER SOURCE)

*a

Front view of wire harness connector

(to Instrument Panel Junction Block Assembly)

(a) Disconnect the instrument panel junction block assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

4L-1 - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

OK

9.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Disconnect the instrument panel junction block assembly connector.

(b) Disconnect the certification ECU (smart key ECU assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4A-17 - G40-17 (IG1D)

Always

Below 1 Ω

4A-17 or G40-17 (IG1D) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

10.

CHECK SMART KEY SYSTEM

(a) Check the smart key system.

Click here

OK

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

NG

REPAIR SMART KEY SYSTEM

11.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY)

(a) Disconnect the instrument panel junction block assembly connector.

(b) Disconnect the stop light switch assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4F-3 - A33-7 (B)

Always

Below 1 Ω

4F-3 or A33-7 (B) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

12.

CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (POWER SOURCE)

*a

Front view of wire harness connector

(to Instrument Panel Junction Block Assembly)

(a) Disconnect the instrument panel junction block assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

4L-1 - Body ground

Always

11 to 14 V

OK

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

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