1ar-fe Engine Control

Starter Signal Circuit

~5min read
DESCRIPTION

1. w/o Smart Key System

While the engine is being cranked, current flows from terminal ST1 of the ignition switch assembly to the park/neutral position switch assembly and also flows to terminal STA of the ECM (STA Signal).

2. w/ Smart Key System

While the engine is being cranked, current flows from terminal STAR of the power management control ECU to the park/neutral position switch assembly and also flows to terminal STA of the ECM (STA signal).

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE
  1. READ VALUE USING TECHSTREAM (STARTER SIGNAL)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Starter Signal.

(e) Read the value displayed on the Techstream when the ignition switch is turned to ON and the engine is started.

OK:

Condition

Techstream Display

Ignition switch ON

OFF (starter signal OFF)

Engine started

ON (starter signal ON)


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG
  1. CHECK ST RELAY (POWER SOURCE)

(a) Inspect the ST relay (See page ).


Result

Proceed to

OK

A

NG (w/o Smart Key System)

B

NG (w/ Smart Key System)

C


A

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - PARK/NEUTRAL POSITION SWITCH ASSEMBLY)


C

GO TO STEP 7

B
  1. CHECK HARNESS AND CONNECTOR (ST RELAY - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM)

(a) Remove the ST relay from the engine room relay block.

(b) Disconnect the park/neutral position switch assembly connector.

(c) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

2 (ST relay terminal) - B2-9 (L)

Always

Below 1 Ω

2 (ST relay terminal) - A49-48 (STA)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

2 (ST relay terminal) or B2-9 (L) - Body ground

Always

10 kΩ or higher

2 (ST relay terminal) or A49-48 (STA) - Body ground

Always

10 kΩ or higher


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ST RELAY - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM)

OK
  1. INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY

(a) Inspect the park/neutral position switch assembly (See page for U760E, See page
for U760F).


Result

Proceed to

OK

A

NG (for U760E)

B

NG (for U760F)

C


B

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY


C

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY

A
  1. CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - ECM - PARK/NEUTRAL POSITION SWITCH)

(a) Disconnect the ignition switch assembly connector.

(b) Disconnect the park/neutral position switch assembly connector.

(c) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

D12-1 (ST1) - B58-47 (NSW)

Always

Below 1 Ω

D12-1 (ST1) - B2-4 (B)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

D12-1 (ST1) or B58-47 (NSW) - Body ground

Always

10 kΩ or higher

D12-1 (ST1) or B2-4 (B) - Body ground

Always

10 kΩ or higher


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH - ECM - PARK/NEUTRAL POSITION SWITCH)

OK
  1. INSPECT IGNITION SWITCH ASSEMBLY

(a) Inspect the ignition switch assembly (See page ).



OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH ASSEMBLY - BATTERY)


NG

REPLACE IGNITION SWITCH ASSEMBLY

  1. CHECK HARNESS AND CONNECTOR (ST RELAY - POWER MANAGEMENT CONTROL ECU - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM)

(a) Disconnect the ECM connector.

(b) Disconnect the park/neutral position switch assembly connector.

(c) Disconnect the power management control ECU connector.

(d) Remove the ST relay from the engine room relay block.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

2 (ST relay terminal ) or A49-48 (STA)

Always

Below 1 Ω

2 (ST relay terminal) - B2-9 (L)

Always

Below 1 Ω

2 (ST relay terminal) - D42-2 (STA)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

2 (ST relay terminal ) or A49-48 (STA) - Body ground

Always

10 kΩ or higher

2 (ST relay terminal ) or B2-9 (L) - Body ground

Always

10 kΩ or higher

2 (ST relay terminal ) or D42-2 (STA) - Body ground

Always

10 kΩ or higher


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ST RELAY - POWER MANAGEMENT CONTROL ECU - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM)

OK
  1. INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY

(a) Inspect the park/neutral position switch assembly (See page for U760E, See page
for U760F).


Result

Proceed to

OK

A

NG (for U760E)

B

NG (for U760F)

C


B

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY


C

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY

A
  1. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - ECM - PARK/NEUTRAL POSITION SWITCH ASSEMBLY)

(a) Disconnect the power management control ECU connector.

(b) Disconnect the ECM connector.

(c) Disconnect the park/neutral position switch assembly connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

D42-3 (STAR) - B58-47 (NSW)

Always

Below 1 Ω

D42-3 (STAR) - B2-4 (B)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

D42-3 (STAR) or B58-47 (NSW) - Body ground

Always

10 kΩ or higher

D42-3 (STAR) or B2-4 (B) - Body ground

Always

10 kΩ or higher


OK

GO TO SMART KEY SYSTEM


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - ECM - PARK/NEUTRAL POSITION SWITCH ASSEMBLY)

Test yourself

A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.