Diagnostic trouble code P0504 3UR-FE Land Cruiser

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK STOP LIGHT SWITCH ASSEMBLY (B+ VOLTAGE)

INSPECT STOP LIGHT SWITCH ASSEMBLY

CHECK ECM (STP AND ST1 - VOLTAGE)

INSPECT FUSE (STOP AND IGN)

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

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 stores the 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

1. [OFF] denotes ground potential.
2. [ON] denotes battery potential (+B).
3. On the intelligent tester, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.

DTC Code	DTC Detection Condition	Trouble Area
P0504	Conditions (a), (b) and (c) continue for 0.5 seconds or more (1 trip detection logic): (a) The engine switch is on (IG). (b) The brake pedal is released. (c) The STP signal is OFF when the ST1- signal is OFF.	Short in stop light switch signal circuit STOP fuse IGN fuse Stop light switch ECM

Wiring diagram

Inspection procedure

HINT:

1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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.
2. STP signal conditions can be checked using the intelligent tester.
   1. Connect the tester to the DLC3.
   2. Turn the engine switch on (IG).
   3. Turn the tester on.
   4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Stop Light Switch and ST1.
   5. Check the Data List indication when the brake pedal is depressed and released.

Brake Pedal Operation	Stop Light Switch	ST1
Depressed	ON	ON
Released	OFF	OFF

1.CHECK STOP LIGHT SWITCH ASSEMBLY (B+ VOLTAGE)

1. Disconnect the A30 stop light switch connector.

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

   Standard Voltage:

   Tester Connection	Switch Condition	Specified Condition
   A30-2 - Body ground	Always	11 to 14 V
   A30-3 - Body ground	Engine switch on (IG)	11 to 14 V

NG	Go to step 4

OK

2.INSPECT STOP LIGHT SWITCH ASSEMBLY

1. Remove the stop light switch.

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

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   1 - 2	Pin not pushed	Below 1 ?
   	Pin pushed	10 k? or higher
   3 - 4	Pin not pushed	10 k? or higher
   	Pin pushed	Below 1 ?

NG	REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

3.CHECK ECM (STP AND ST1 - VOLTAGE)

1. Disconnect the A38 or A53 ECM connector.

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

   Standard Voltage:

   Tester Connection	Condition	Specified Condition
   A38-35 (ST1-) - Body ground	Brake pedal released	11 to 14 V
   	Brake pedal depressed	0 to 3 V
   A38-36 (STP) - Body ground	Brake pedal released	0 to 3 V
   	Brake pedal depressed	11 to 14 V

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE ECM

4.INSPECT FUSE (STOP AND IGN)

1. Remove the STOP and IGN fuses from the engine room relay block.

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

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   STOP fuse	Always	Below 1 ?
   IGN fuse	Always	Below 1 ?

NG	CHECK FOR SHORTS IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

OK
REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - STOP LIGHT SWITCH)