Lexus ES300 (1997 year). Service manual - part 311

DI–20

–

DIAGNOSTICS

ENGINE

172

1997 LEXUS ES300   (RM511U)

Symbols (Terminals No.)

Wiring Color

Condition

STD Voltage (V)

IGF (E10

12)

IG switch ON

4.5 

∼

 5.5

IGF (E10 – 12)

                     – E1 (E8 – 16)

W–R 

↔

BR

Idling

Pulse generation

(See page 

DI–112

)

THG (E8 – 14) – E2 (E9 – 22)

G–Y 

↔

BR

IG switch ON

4.5 

∼

 5.5

G22+ (E9 – 17)

                 –  NE– (E9 – 6)

B–W 

↔

L

Idling

Pulse generation

(See page 

DI–66

)

NE+ (E9 – 5)

                    –  NE– (E9 – 6)

B–R 

↔

L

Idling

Pulse generation

(See page 

DI–66

)

ELS (E7

3)

E1 (E8

16)

G O

BR

Taillight switch ON

7.5 

∼

 14

ELS (E7 – 3) – E1 (E8 – 16)

G–O 

↔

BR

Taillight switch OFF

0 

∼

 1.5

ELS2 (E7

2)

E1 (E8

16)

B Y

BR

Defogger switch ON

7.5 

∼

 14

ELS2 (E7 – 2) – E1 (E8 – 16)

B–Y 

↔

BR

Defogger switch OFF

0 

∼

 1.5

EGR (E8 – 12)

                    –  E01 (E10 –34)

Y–G 

↔

BR

IG switch ON

9 

∼

 14

ACIS (E8 – 6)

                   – E01 (E10 – 34)

R–G 

↔

BR

IG switch ON

9 

∼

 14

FC (E9

18)

E1 (E8

16)

G R

BR

IG switch ON

9 

∼

 14

FC (E9 – 18) – E1 (E8 – 16)

G–R 

↔

BR

Idling

0 

∼

 3.0

EVP1 (E8 – 2)

                   – E01 (E10 – 34)

LG 

↔

BR

IG switch ON

9 

∼

 14

RSC (E10 – 22)

                     – E01 (E10 – 34)

Y–B 

↔

BR

IG switch ON

Disconnect E10 of ECM connector

9 

∼

 14

RSO (E10 – 23)

                     – E01 (E10 – 34)

R–W 

↔

BR

IG switch ON

Disconnect E10 of ECM connector

9 

∼

 14

OXR1 (E9 – 13)

                        – E1 (E8 – 16)

W 

↔

BR

Maintain engine speed at 2,500 rpm for 2 min. after

 warming up

Pulse generation

(See page 

DI–84

)

OXL1 (E9 – 19)

                       – E1 (E8 – 16)

B 

↔

BR

Maintain engine speed at 2,500 rpm for 2 min. after

 warming up

Pulse generation

(See page 

DI–84

)

OXS (E7 – 18)

                      – E1 (E8 – 16)

B 

↔

BR

Maintain engine speed at 2,500 rpm for 2 min. after

 warming up

Pulse generation

(See page 

DI–84

)

HTL (E8– 10)

Y R

BR

Idling

Below 3.0

HTL (E8  10)

                  – E03 (E10 – 28)

Y–R 

↔

BR

IG switch ON

9 

∼

 14

HTR (E8 – 11)

L B

BR

Idling

Below 3.0

HTR (E8   11)

                   – E03 (E10 – 28)

L–B 

↔

BR

IG switch ON

9 

∼

 14

HTS (E7 – 17)

P B

BR

Idling

Below 3.0

HTS (E7   17)

                   – E03 (E10 –28)

P–B 

↔

BR

IG switch ON

9 

∼

 14

KNKR (E9 – 15)

                     – E1 (E8 – 16)

W 

↔

BR

Idling

Pulse generation

(See page 

DI–62

)

KNKL (E9 – 14)

                    – E1 (E8 – 16)

W 

↔

BR

Idling

Pulse generation

(See page 

DI–62

)

NSW (E10 – 14)

B W

BR

IG switch ON

Other shift position in ”P” ,”N” position

9 

∼

 14

NSW (E10   14)

                      – E1 (E8 – 16)

B–W 

↔

BR

IG switch ON

Shift position in ”P” ,”N” position

0 

∼

 3.0

SPD (E7 – 12)

                   – E1 (E8 – 16)

V–W 

↔

BR

IG switch ON

Rotate driving wheel slowly

Pulse generation

TC (E8 – 5) – E1 (E8 – 16)

L–W 

↔

BR

IG switch ON

9 

∼

 14

–

DIAGNOSTICS

ENGINE

DI–21

173

1997 LEXUS ES300   (RM511U)

Symbols (Terminals No.)

Wiring Color

Condition

STD Voltage (V)

W (E8 – 3) – E1 (E8 – 16)

G–R 

↔

BR

IG switch ON

Below 3.0

PS (E10 – 31) – E1 (E8 – 16)

B 

↔

 L

IG switch ON

9 

∼

 14

ACT (E7

5)

E1 (E8

16)

B Y

BR

A/C switch OFF

Below 2.0

ACT (E7 – 5) – E1 (E8 – 16)

B–Y 

↔

BR

A/C switch ON at idling

9 

∼

 14

A/C (E7

16)

E1 (E8

16)

LG W

BR

A/C switch ON at idling

Below 2.0

A/C (E7 – 16)  – E1 (E8 – 16)

LG–W 

↔

BR

A/C switch OFF

9 

∼

 14

CF (E8

9)

E1 (E8

16)

G W

BR

Electric cooling fan is operating on high speed

9 

∼

 14

CF (E8 – 9) – E1 (E8 – 16)

G–W 

↔

BR

Electric cooling fan is operating on low speed or OFF

0 

∼

 2

TACH (E7 – 13)

                      – E1 (E8–16)

B–O 

↔

BR

Idling

Pulse generation

TPC (E8 – 8)

                    – E1 (E8 – 16)

W–R 

↔

BR

IG switch ON

Disconnect the vacuum hose from the vapor pressure sensor

9 

∼

 14

IG switch ON

3.0 

∼

 3.6

PTNK (E8 – 13) – E1 (E8 – 16)

L–R 

↔

BR

IG switch ON

Apply vacuum 2.0 kPa (15 mmHg, 0.6 in.Hg)

1.3 

∼

 2.1

SIL (E7 – 8) – E1 (E8 – 16)

W 

↔

BR

During transmission

Pulse generation

STP (E7

24)

E1 (E8

16)

G W

BR

IG switch ON

Brake pedal depressed

7.5 

∼

 14

STP (E7 – 24) – E1 (E8 – 16)

G–W 

↔

BR

IG switch ON

Brake pedal  released

Below 1.5

EGLS (E8

15)

E1 (E8

16)

W G

BR

IG switch ON

Apply vacuum (0 kPa, 0 mmHg, 0 in.Hg) to EGR valve

0.4 

∼

 1.6

EGLS (E8 – 15) – E1 (E8 – 16)

W–G 

↔

BR

IG switch ON

Apply vacuum (17.3 kPa, 130 mmHg, 5.12 in.Hg) to EGR valve

3.2 

∼

 5.1

DI09A–01

DI–22

–

DIAGNOSTICS

ENGINE

174

1997 LEXUS ES300   (RM511U)

PROBLEM SYMPTOMS TABLE

Symptom

Suspect Area

See page

Engine does not crank (Does not start)

1. Starter and starter relay

ST–18

ST–20

No initial combustion (Does not start)

1. ECM power source circuit

2. Fuel pump control circuit

3. Engine control module (ECM)

DI–132

DI–138

IN–27

No complete combustion (Does not start)

1. Fuel pump control circuit

DI–138

Engine cranks normally (Difficult to start)

1. Starter signal circuit

2. Fuel pump control circuit

3. Compression

DI–132

DI–138

EM–3

Cold engine (Difficult to start)

1. Starter signal circuit

2. Fuel pump control circuit

DI–132

DI–138

Hot engine

1. Starter signal circuit

2. Fuel pump control circuit

DI–132

DI–138

High engine idle speed (Poor idling)

1. A/C signal circuit (Compressor circuit)

2. ECM power source circuit

DI–569

DI–135

Low engine idle speed (Poor idling)

1. A/C signal circuit  (Compressor circuit)

2. Fuel pump control circuit

DI–569

DI–138

Rough idling (Poor idling)

1. Compression

2. Fuel pump control circuit

EM–3

DI–138

Hunting (Poor idling)

1. ECM power source circuit

2. Fuel pump control circuit

DI–135

DI–138

Hesitation/Poor acceleration (Poor driveability)

1. Fuel pump control circuit

2. A/T faulty

DI–138

DI–148

Surging

1. Fuel pump control circuit

DI–138

Soon after starting (Engine stall)

1. Fuel pump control circuit

DI–138

During A/C operation (Engine stall)

1. A/C signal circuit (Compressor circuit)

2. Engine control module (ECM)

DI–569

IN–27

DI09B–01

A00435

B+

Thermister

Power Transister

Platinum Hot wire

B

Output

Platinum Hot
Wire

A

Voltage

Thermister

FI6929

S05741

–

DIAGNOSTICS

ENGINE

DI–23

175

1997 LEXUS ES300   (RM511U)

CIRCUIT INSPECTION

DTC

P0100

Mass Air Flow Circuit Malfunction

CIRCUIT DESCRIPTION

The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire,
thermistor and a control circuit installed in a plastic housing. The hot wire air flow meter works on the principle
that the hot wire and thermistor located in the intake air bypass of the housing detect any changes in the
intake air temp.
The hot wire is maintained at the set temp. by controlling the current flow through the hot wire. This  current
flow is then measured as the output voltage of the air flow meter.
The circuit is constructed so that the platinum hot wire and thermistor provide a bridge circuit,with the power
transistor controlled so that the potential of A and B remains equal to maintain the set temp.

DTC No.

DTC Detecting Condition

Trouble Area

P0100

Open or short in mass air flow meter circuit with more than 3

sec. engine speed 4,000 rpm or less

Open or short in mass air flow meter circuit

Mass air flow meter

ECM

If the ECM detects DTC ”P0100” it operates the fail–safe function, keeping the ignition timing and injection
volume constant and making it possible to drive the vehicle.
HINT:After confirming DTC P0100 use the OBD II scan tool or LEXUS hand–held tester to confirm the mass
air flow ratio from ”CURRENT DATA”.

Mass Air Flow Value (gm/sec.)

Malfunction

0.0

Mass air flow meter power source circuit open

VG circuit open or short

271.0 or more

E2G circuit open