Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

Read freeze frame data using 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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).

CHECK STOP LIGHT (OPERATION OF STOP LIGHT)
1. Check whether the stop lights turn on and off normally when the brake pedal is depressed and released.
  OK:
  
  Stop lights turn ON when brake pedal is depressed.
  
  NG: REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
  
  OK: Go to next step

READ VALUE OF TECHSTREAM (STP SIGNAL AND ST1 - VOLTAGE)

Connect Techstream to the DLC3.
Turn the engine switch on (IG) and turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch.

Check the STP signal when the brake pedal is depressed and released.

BRAKE PEDAL OPERATION CHART

Brake Pedal Operation	Specified Condition
Depressed	STP signal ON
Released	STP signal OFF

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

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Brake Pedal Operation	Specified Condition
ST1 - (A5-8) - E1 (E4-7)	Depressed	Below 1.5 V
ST1 - (A5-8) - E1 (E4-7)	Released	7.5 to 14 V

Fig 1: Identifying Terminals Of E4 And A5 ECM Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: CHECK FOR INTERMITTENT PROBLEMS

NG: Go to next step

INSPECT STOP LIGHT SWITCH ASSEMBLY

Remove the stop light switch assembly.

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

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

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

Reinstall the stop light switch assembly.

Fig 2: Identifying Terminals Of Stop Light Switch Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPLACE STOP LIGHT SWITCH ASSEMBLY

OK: Go to next step

CHECK ECM (STP, ST1 -VOLTAGE)

Disconnect the A5 and A6 ECM connectors.
Measure the voltage according to the value(s) in the table below.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Brake Pedal Operation	Specified Condition
STP (A6-4) - Body ground	Depressed	9 to 14 V
STP (A6-4) - Body ground	Released	0 to 3 V
ST1- (A5-8) - Body ground	Depressed	0 to 3 V
ST1- (A5-8) - Body ground	Released	9 to 14 V

Fig 3: Identifying Terminals Of A5 And A6 ECM Connectors

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE ECM