Lexus ES300 (1997 year). Manual - part 312

S06671

Engine Room J/B

EFI Relay

Junction
Connector

Fusible
Link
Block

From Ignition Switch

J23

Battery

FL
MAIN

EFI

2A

2K

2J

2F

B

B–R

EB

7

1

2

5

1

3

2

IGN

7

3

1W

1K

F8

F6

1

1

B–G

Junction
Connector

Mass Air
Flow Meter

B–Y

B–Y

B–Y

B–Y

W–B

R–B

ECM

E2G

VG

E2

E9

E8

P

4

J29

J28

B

B

IK3

9

4

A

A

5

3

8

7

Instrument Panel
J/B

DI–24

–

DIAGNOSTICS

ENGINE

176

1997 LEXUS ES300   (RM511U)

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Connect OBD II scan tool or LEXUS hand–held tester, and read value of mass air
flow rate.

PREPARATION:
(a)

Connect the OBD II scan tool or LEXUS hand–held tester to the DLC3.

(b)

Turn ignition switch ON and push the OBD II scan tool or LEXUS hand–held tester main switch ON.

(c)

Start the engine.

CHECK:
Read mass air flow rate on the OBD II scan tool or LEXUS hand–held tester.
RESULT:

Type I

Type II

Mass air flow rate (gm/sec.)

0.0

271.0 or more

Type I

 Go to step 2.

Type II

 Go to step 5.

A00436

ON

4(+)

BE6653
S05337

S05699

VG(+)

–

DIAGNOSTICS

ENGINE

DI–25

177

1997 LEXUS ES300   (RM511U)

2

Check voltage of mass air flow meter power source.

PREPARATION:
(a)

Disconnect the mass air flow meter connector.

(b)

Turn ignition switch ON.

CHECK:
Measure voltage between terminal 4 of mass air flow meter con-
nector and body ground.
OK:

Voltage: 9 

∼

 14 V

NG

 Check for open in harness and connector
between EFI main relay (Marking: EFI) and
mass air flow meter (See page 

IN–27

).

OK

3

Check voltage between terminal VG of ECM connector and body ground.

PREPARATION:
(a)

Remove the glove compartment (See page 

SF–64

).

(b)

Start the engine.

CHECK:
Measure voltage between terminal VG of ECM and body
ground while engine is idling.
OK:

Voltage: 
1.1 

∼

 1.5 V (P or N position and A/C switch OFF)

OK

 Check and replace ECM (See page 

IN–27

).

NG

P23859

E2G

DI–26

–

DIAGNOSTICS

ENGINE

178

1997 LEXUS ES300   (RM511U)

4

Check for open and short in harness and connector between mass air flow meter
and ECM (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

Replace mass air flow meter.

5

Check continuity between terminal E2G of ECM and body ground.

PREPARATION:
Remove the glove compartment (See page 

SF–64

).

CHECK:
Check continuity between terminal E2G of ECM connector and
body ground.
OK:

Continuity (1 

Ω

 or less)

NG

 Check and replace ECM (See page 

IN–27

).

OK

6

Check for open in harness and connector between mass air flow meter and ECM
(See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

 Replace mass air flow meter.

–

DIAGNOSTICS

ENGINE

DI–27

179

1997 LEXUS ES300   (RM511U)

DTC

P0101

Mass Air Flow Circuit Range/Performance
Problem

CIRCUIT DESCRIPTION

Refer to DTC P0100 (Mass Air Flow Circuit Malfunction) on page 

DI–23

.

DTC No.

DTC Detecting Condition

Trouble Area

P0101

Conditions (a), (b) and (c) continue 10 sec. or more with

engine speed 900 rpm or less:

(2 trip detection logic)

(a) Throttle valve fully closed

(b) Mass air flow meter output 



 2.2 V

(c) THW 

>

 70

°

C

Mass air flow meter

P0101

Conditions (a) and (b) continue 10 sec. or more with engine

speed 1,500 rpm or more: 

(2 trip detection logic)

(a) VTA 



 0.63 V

(b) Mass air flow meter output 

 1.06 V

Mass air flow meter

WIRING DIAGRAM

Refer to DTC P0100 on page 

DI–23

 for the WIRING DIAGRAM.

INSPECTION PROCEDURE

1

Are there any other codes (besides DTC P0101) being output?

NO

 Replace mass air flow meter.

YES

Go to relevant DTC chart.

DI09C–01