Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

READ VALUE OF DATA LIST (STOP LIGHT SWITCH)

Check the DATA LIST for proper functioning of the stop light switch.

ECM (cruise control)

ITEM MEASUREMENT NORMAL CONDITION CHART

Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
STP LIGHT SW M	Stop light switch signal (Main CPU) / ON or OFF	ON: Brake pedal is depressed OFF: Brake pedal is released	-
STP LIGHT SW S2	Stop light switch signal (Sub CPU / ON or OFF	ON: Brake pedal is depressed OFF: Brake pedal is released	-
STP LIGHT SW S1	Stop light switch signal (Sub CPU) / ON or OFF	ON: Brake pedal is depressed OFF: Brake pedal is released	-

OK:

OK: Display changes according to brake pedal operation described in above table.

HINT:

Stop light SW S1 has a function to disconnect the connection (OFF) when the pedal is depressed. However, the intelligent tester displays ON, as the ECM performs control using reverse logic.
Stop light SW S1 indicates the input of ST1 - terminal, and stop light SW S2 indicates the input of STP terminal.

OK: REPLACE ECM

NG: Go to next step

INSPECT STOP LIGHT SWITCH ASSEMBLY

Disconnect the stop light switch connector.

Measure the resistance of the switch.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Switch Condition	Specified Condition
1 - 2	Pin not pushed (Brake pedal depressed)	Below 1 Ω
3 - 4	Pin not pushed (Brake pedal depressed)	10 kΩ or higher
1 - 2	Pin pushed (Brake pedal released)	10 kΩ or higher
3 - 4	Pin pushed (Brake pedal released)	Below 1 Ω

NG: REPLACE STOP LIGHT SWITCH

Fig 1: Inspecting Stop Light Switch Assembly

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to next step

CHECK WIRE HARNESS (ECM - BODY GROUND)

Disconnect the E5 and E6 ECM connectors.
Turn the ignition switch ON.

Measure the voltage of the wire harness side connectors.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Brake Pedal Condition	Specified Condition
E5-4 (STP) - Body ground	Depressed	10 to 14 V
E5-4 (STP) - Body ground	Released	Below 1 V
E6-8 (ST1-) - Body ground	Depressed	Below 1 V
E6-8 (ST1-) - Body ground	Released	10 to 14 V

Result

RESULT REFERENCE CHART

Result	Proceed to
OK	A
NG (STP terminal is NG)	B
NG (ST1 - terminal is NG)	C

A: REPLACE ECM

C: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 2: Disconnecting E5 And E6 ECM Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

B: Go to next step

INSPECT FUSE (STOP)
1. Remove the STOP fuse from the driver side junction block ECU.
2. Measure the resistance of the fuse.
  Standard resistance:
  
  Below 1 Ω
NG: REPLACE FUSE

OK: Go to next step

CHECK WIRE HARNESS (MAIN BODY ECU - BATTERY)

Disconnect the D2 ECU connector.

Measure the voltage of the wire harness side connector.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Brake Pedal Condition	Specified Condition
D2-13 (STPI) - Body ground	Depressed	10 to 14 V
D2-13 (STPI) - Body ground	Released	Below 1 V

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 3: Identifying D2 Wire Harness Side Connector Terminals

OK: Go to next step

CHECK MAIN BODY ECU (for Driver Side)

Reconnect the D2 ECU connector.

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

Fig 4: Identifying D2 Driver Side Junction Block Connector Terminals

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Brake Pedal Condition	Specified Condition
D2-12 (STPO) - Body ground	Depressed	10 to 14 V
D2-12 (STPO) - Body ground	Released	Below 1 V

NG: REPLACE MAIN BODY ECU (for Driver Side)

OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU - ECM)