Toyota TechDoc

ECD SYSTEM > Starter Signal Circuit

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DESCRIPTION

w/o Entry and Start System:
While the engine is being cranked, current flows from terminal ST1 of the ignition switch to the clutch start switch and also flows to terminal STA of the ECM (STA Signal).
w/ Entry and Start System:
While the engine is being cranked, the ECM receives the STA signal from the power management ECU, and then the ECM performs starting based on its signal.

WIRING DIAGRAM

INSPECTION PROCEDURE

1.READ VALUE USING INTELLIGENT TESTER (STARTER SIGNAL)

Connect an intelligent tester to the DLC3.

Turn the ignition switch to ON and turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / Data List / Starter Signal.

Check the result when the ignition switch is turned to ON and when the engine is started.
OK:
Ignition Switch Condition
Display (Starter Signal)
ON
OFF
Engine start
ON
Result
Result
Proceed to
NG (w/ Entry and Start System)
A
NG (w/o Entry and Start System)
B
OK (w/ Entry and Start System)
C
OK (w/o Entry and Start System)
D

Result
Result	Proceed to
NG (w/ Entry and Start System)	A
NG (w/o Entry and Start System)	B
OK (w/ Entry and Start System)	C
OK (w/o Entry and Start System)	D

Go to step 5

CHECK ENTRY AND START SYSTEM (Click here)

Go to step 10

A

2.INSPECT CLUTCH START SWITCH ASSEMBLY (POWER SOURCE)

Remove the clutch start switch.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Switch Condition
Specified Condition
1 - 2
ON (Pushed)
Below 1 Ω
1 - 2
OFF (Not pushed)
10 kΩ or higher

Reinstall the clutch start switch.

REPLACE CLUTCH START SWITCH ASSEMBLY (Click here)

OK

3.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - ECM)

Disconnect the clutch start switch connector.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Tester Connection
Condition
Specified Condition
A29-1 - A19-6 (STA)
Always
Below 1 Ω
Standard Resistance (Check for Short):
Tester Connection
Condition
Specified Condition
A29-1 or A19-6 (STA) - Body ground
Always
10 kΩ or higher
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)
*2
Front view of wire harness connector
(to ECM)

Text in Illustration
*1	Front view of wire harness connector (to Clutch Start Switch)
*2	Front view of wire harness connector (to ECM)

Reconnect the clutch start switch connector.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - POWER SOURCE CONTROL ECU)

Disconnect the clutch start switch connector.

Disconnect the power source control ECU connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Tester Connection
Condition
Specified Condition
A29-2 - D72-3 (STAR)
Always
Below 1 Ω
Standard Resistance (Check for Short):
Tester Connection
Condition
Specified Condition
A29-2 or D72-3 (STAR) - Body ground
Always
10 kΩ or higher
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)
*2
Front view of wire harness connector
(to Power Source Control ECU)

Text in Illustration
*1	Front view of wire harness connector (to Clutch Start Switch)
*2	Front view of wire harness connector (to Power Source Control ECU)

Reconnect the clutch start switch connector.

Reconnect the power source control ECU connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK ENTRY AND START SYSTEM (Click here)

5.INSPECT CLUTCH START SWITCH ASSEMBLY

Disconnect the clutch start switch connector.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
A29-2 - Body ground
Ignition switch START
11 to 14 V
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)

Text in Illustration
*1	Front view of wire harness connector (to Clutch Start Switch)

Reconnect the clutch start switch connector.

Go to step 8

OK

6.INSPECT CLUTCH START SWITCH ASSEMBLY

Remove the clutch start switch.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Switch Condition
Specified Condition
1 - 2
ON (Pushed)
Below 1 Ω
1 - 2
OFF (Not pushed)
10 kΩ or higher

Reinstall the clutch start switch.

REPLACE CLUTCH START SWITCH ASSEMBLY (Click here)

OK

7.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - ECM - ST RELAY)

Disconnect the clutch start switch connector.

Remove the ST relay from the engine room relay block.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Tester Connection
Condition
Specified Condition
A29-1 - A19-6 (STA)
Always
Below 1 Ω
A29-1 - 2 (ST relay)
Always
Below 1 Ω
Standard Resistance (Check for Short):
Tester Connection
Condition
Specified Condition
A29-1 or A19-6 (STA) - Body ground
Always
10 kΩ or higher
A29-1 or 2 (ST relay) - Body ground
Always
10 kΩ or higher
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)
*2
Front view of wire harness connector
(to ECM)
*3
Engine Room Relay Block
*4
ST Relay

Reconnect the clutch start switch connector.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM (Click here)

8.INSPECT IGNITION SWITCH

Remove the ignition switch.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Switch Condition
Specified Condition
All terminals
LOCK
10 kΩ or higher
2 - 3
ACC
Below 1 Ω
2 - 3 - 4, 6 - 7
ON
Below 1 Ω
1 - 2 - 4, 6 - 7 - 8
START
Below 1 Ω
Text in Illustration
*1
Component without harness connected
(Ignition Switch)

Reinstall the ignition switch.

REPLACE IGNITION SWITCH (Click here)

OK

9.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - IGNITION SWITCH - ST RELAY)

Remove the ST relay from the engine room relay block.

Disconnect the clutch start switch connector.

Disconnect the ignition switch connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Tester Connection
Condition
Specified Condition
A29-2 - D28-1 (ST1)
Always
Below 1 Ω
D28-8 (ST2) - 5 (ST relay)
Always
Below 1 Ω
Standard Resistance (Check for Short):
Tester Connection
Condition
Specified Condition
A29-2 or D28-1 (ST1) - Body ground
Always
10 kΩ or higher
D28-8 (ST2) or 5 (ST relay) - Body ground
Always
10 kΩ or higher
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)
*2
Front view of wire harness connector
(to Ignition Switch)
*3
Engine Room Relay Block
*4
ST Relay

Reconnect the clutch start switch connector.

Reconnect the ignition switch connector.

Reinstall the ignition switch.

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

10.CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - ECM - ST RELAY)

Disconnect the clutch start switch connector.

Remove the ST relay from the engine room relay block.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Tester Connection
Condition
Specified Condition
A29-1 - A19-6 (STA)
Always
Below 1 Ω
A29-1 - 2 (ST relay)
Always
Below 1 Ω
Standard Resistance (Check for Short):
Tester Connection
Condition
Specified Condition
A29-1 or A19-6 (STA) - Body ground
Always
10 kΩ or higher
A29-1 or 2 (ST relay) - Body ground
Always
10 kΩ or higher
Text in Illustration
*1
Front view of wire harness connector
(to Clutch Start Switch)
*2
Front view of wire harness connector
(to ECM)
*3
Engine Room Relay Block
*4
ST Relay

Reconnect the clutch start switch connector.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Click here)

Ignition Switch Condition	Display (Starter Signal)
ON	OFF
Engine start	ON

Tester Connection	Switch Condition	Specified Condition
1 - 2	ON (Pushed)	Below 1 Ω
1 - 2	OFF (Not pushed)	10 kΩ or higher

Tester Connection	Condition	Specified Condition
A29-1 - A19-6 (STA)	Always	Below 1 Ω

*1	Front view of wire harness connector (to Clutch Start Switch)
*2	Front view of wire harness connector (to ECM)
*3	Engine Room Relay Block
*4	ST Relay