Lexus SC300 / Lexus SC400. Service manual — part 906

STANDARD VALUE OF ECU TERMINALS (Cont’d)

Symbols (Terminals No.)

STD Voltage (V)

Condition

ISC1 (B35), ISC2 (B34)

E1 (B69)

10

14

IG switch ON

ISC1 (B35), ISC2 (B34)
ISC3 (B33), ISC4 (B32)

–E1 (B69)

10 ~ 14

IG switch ON

VF1 (B29), VF2 (B28) – E1 (B69)

1.0 ~ 4.0

Maintain engine speed at 2,500 rpm for two
minutes
after warming up then return to idling.

OXL1 (B48), OXR1 (B47) – E1 (B69)

Pulse generation

(0 ~ 1.0)

Maintain engine speed at 2,500 rpm for two
minutes
after warming up.

HTL1 (B71), HTR1 (B72)

E01 (B80)

Below 2.0

Idling

HTL1 (B71), HTR1 (B72)
HTL2 (B52), HTR2 (B53)

– E01 (B80)

10 ~ 14

IG switch ON

EGR1 (B39), EGR2 (B38)

E1 (B69)*

10

14

IG switch ON

EGR1 (B39), EGR2 (B38)
EGR3 (B37), EGR4 (B36)

– E1 (B69)*

10 ~ 14

IG switch ON

EGR (B39) – E1 (B69)

10 ~ 14

IG switch ON

KNK1 (B50), KNK2 (B49) – E1 (B69)

Pulse generation

(Frequency : 6.6 KHz)

Idling

NSW (B76)

E1 (B69)

10 ~ 14

IG switch ON
Other shift position in ”P”, ”N” ranges.

NSW (B76) – E1 (B69)

Below 1.0

IG switch ON
Shift position in ”P”, ”N” ranges.

SPD (A2)–E1 (B69)

Pulse generation

(0 and 10 ~ 14)

IG switch ON
Rotate driving wheel slowly.

TE1 (A20) – E1 (B69)

10 ~ 14

IG switch ON

TE2 (A19) – E1 (B69)

10 ~ 14

IG switch ON

W (A6) E1 (B69)

10 ~ 14

Idling

W (A6)–E1 (B69)

Below 2.0

IG switch ON

AD (A11) – E1 (B69)

10 ~ 14

Idling

ODI (A12) – E1 (B69)

4.0 ~ 6.0

IG switch ON

A/C (A34)

E1 (B69)

Bellow 2.0

A/C switch ON (At idling)

A/C (A34) – E1 (B69)

10 ~ 14

A/C switch OFF

ACMG (A23) E1 (B69)

Below 2.0

A/C switch ON (At idling)

ACMG (A23)–E1 (B69)

10 ~ 14

A/C switch OFF

TR (A37) – E1 (B69)

10 ~ 14

IG switch ON

Below 1 0

IG switch ON

VTO1 (A40)

E2 (B65)

Below 1.0

IG switch ON
Main or sub throttle valve fully closed.

VTO1 (A40)
VTO2 (A39)

– E2 (B65)

3 0

5 5

IG switch ON

(

)

3.0 ~ 5.5

IG switch ON
Main or sub throttle valve fully open.

NEO (A38) – E1 (B69)

4.0 ~ 6.0

IG switch ON

* Only for USA specification vehicles.

TR–34

–

ENGINE TROUBLESHOOTING

Standard Value of ECU Terminals

TERMINALS OF ECU

Connectors of the engine (& ECT) ECU are water–proof and
are the bolt type.
For water proof type connectors, in order to measure the volt-
age of ECU terminals and the resistance of connected parts,
connect the inspection sub wire harness between the ECU
and vehicle wire harness, then perform the inspection.
The inspection method of inserting a tester probe from the
other side of connector noticeably reduces the water–proof
ability.
Disconnect the connector by fully loosening the bolt.

PREPARATION

1.

Turn the ignition switch to LOCK position.

2.

Turn up the passenger side floor mat.

3.

Remove the ECU protector.

4.

Disconnect the connector from the ECU.
After completely loosening the bolt, the two parts of the con-
nector can be separated.
NOTICE:

•

Do not pully the wire harness when disconnecting the

connector.

•

When disconnecting the connector, the ECU’s backup

power source is cut off, so the malfunction codes, etc.

recorded in the ECU memory are cancelled.

•

Never insert a tester probe or male terminal used for

inspection purposes into the female terminal of the

vehicle wire harness. Otherwise, the female terminal may

be widened, which can result in faulty connection.

5. Connect the Check Harness A between ECU and

connector of vehicle wire harness.
SST 09990–01000
HINT: The arrangement of the check connector terminals are
the same as those of the ECU.
See page

TR–35

6.

Disconnect the Check Harness A.

7.

Reconnect the connector to the ECU.
(a) Match the male connector correctly with the female

connector, then press them together.

(b) Tighten the bolt
Make sure the connector is completely connected, by tight-
ening the bolt until there is a clearance of less than 1 mm
(0.04 in.) between bottom of the male connector and end of
the female connector.

8.

Install the ECU protector and floor mat.

TR–34

–

ENGINE TROUBLESHOOTING

Terminals of ECU

TERMINALS OF ECU

*1: Only vehicles with ECT.

–

ENGINE TROUBLESHOOTING

Terminals of ECU

TR–35

TERMINALS OF ECU (Cont’d)

*1: Only vehicles with ECT.
*2: Only for USA specification vehicles.

TR–36

–

ENGINE TROUBLESHOOTING

Terminals of ECU