Lexus RX300 (MCU15). Manual - part 216

DI–96

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

DTC

P1300

Igniter Circuit Malfunction (No. 1)

DTC

P1305

Igniter Circuit Malfunction (No. 2)

DTC

P1310

Igniter Circuit Malfunction (No. 3)

DTC

P1315

Igniter Circuit Malfunction (No. 4)

DTC

P1320

Igniter Circuit Malfunction (No.5)

DTC

P1325

Igniter Circuit Malfunction (No.6)

CIRCUIT DESCRIPTION

A Direct Ignition System (DIS) has been adopted. The DIS improves the ignition timing accuracy, reduces
high–voltage loss, and enhances the the overall reliability of the ignition system by eliminating the distributor.
The DIS is a 1–cylinder ignition system which ignites one cylinder with one ignition coil. In the 1–cylinder
ignition system, the one spark plug is connected to the end of the secondary winding. High voltage generated
in the secondary winding is applied directly to the spark plug. The spark of the spark plug pass from the center
electode to the ground electrode.
The engine ECU determines ignition timing and outputs the ignition signals (IGT) for each cylinder. Based
on IGT signals, the power transistors in the igniter cuts off the current to the primary coil in the ignition coil
is supplied to the spark plug that are connected to the end of the secondary coil. At the same time, the igniter
also sends an ignition confirmation signal (IGF) as a fail–safe measure to the engine ECU.

DTC No.

DTC Detecting Condition

Trouble Area

P1300

P1305

P1310

P1315

P1320

P1325

No IGF signal to engine ECU while engine is running

S Open or short in IGF and IGT1 – 6 circuit from 

ignition coil with igniter

S No. 1 – No. 6 ignition coil with igniter

S Engine ECU

DI84F–01

A14518

W–L (*1)
W–R (*2)

Engine Room J/B

F11 FL Block

AM2

3

6

Engine ECU

IGT1

E8

EB

1

1

B–Y

2

3

4

W

11

IG2

2I

AM2

1

1

IGT2

E8

12

IGT3

E8

13

IGF

E8

25

IGT4

E8

14

IGT5

E8

15

IGT6

E8

16

(*1): LHD
(*2): RHD

Battery

W

6

2C

7

Instrument Panel J/B

B

1

1C

3

1C

3

1G

12

1G

W–R

Noise
Filter

1

IH1

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–R

W–B

W–B

G–B

I6 Ignition Coil 
and Igniter No. 6

W–B

W–B

W–B

4

2

1

3

I5 Ignition Coil 
and Igniter No. 5

Y

W–B

4

2

1

3

B

B

B

B

I4 Ignition Coil 
and Igniter No. 4

L–Y

W–B

W–B

B

4

2

1

3

Y–G

W–B

I3 Ignition Coil 
and Igniter No. 3

4

2

1

3

B

B

B

B

B

W–B

L–R

4

3

1

2

I2 Ignition Coil 
and Igniter No. 2

I1 Ignition Coil 
and Igniter No. 1

W–B

1

I15
Ignition Switch

W–R

–

DIAGNOSTICS

ENGINE

DI–97

LEXUS RX300   (RM785E)

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

S

If DTC P1300 is displayed, check No. 1 ignition coil with igniter circuit.

S

If DTC P1305 is displayed, check No. 2 ignition coil with igniter circuit.

S

If DTC P1310 is displayed, check No. 3 ignition coil with igniter circuit.

S

If DTC P1315 is displayed, check No. 4 ignition coil with igniter circuit.

S

If DTC P1320 is displayed, check No. 5 ignition coil with igniter circuit.

S

If DTC P1325 is displayed, check No. 6 ignition coil with igniter circuit.

S

Read freeze frame data using hand–held tester. Because freeze frame records the engine conditions
when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle
was running or stopped, the engine warmed up or not, the air–fuel ratio lean or rich, etc. at the time
of the malfunction.

A02033

IGF

ON

(+)

(–)

DI–98

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

1

Check spark plug and spark (See page IG–1).

NG

Go to step 4.

OK

2

Check for open and short in harness and connector in IGF and IGT signal circuit
between engine ECU and ignition coil with igniter (See page IN–32).

NG

Repair or replace harness or connector.

OK

3

Disconnect ignition coil with igniter connector, and check voltage between 
terminals IGF of engine ECU connector and body ground.

PREPARATION:
(a)

Remove the engine ECU with connector still connected
(See page FI–70).

(b)

Disconnect the ignition coil with the igniter connector.

(c)

Turn the ignition switch ON.

CHECK:
Measure voltage between terminals IGF of the engine ECU
connector and body ground.
OK:

Voltage: 4.5 – 5.5 V

OK

Replace ignition coil with igniter.

NG

Check and replace engine ECU (See page
 IN–32).

4

Check for open and short in harness and connector in IGT signal circuit between
engine ECU and ignition coil with igniter (See page IN–32).

A07629

ON

IGT1

IGT4

IGT2

IGT3

(+)

(–)

IGT5

IGT6

A06097

IGT Signal Waveform

5 V/
Division

IGT

GND

IGF

GND

20 msec./Division

A07629

ON

IGT1

IGT4

IGT2

IGT3

(+)

(–)

IGT5

IGT6

–

DIAGNOSTICS

ENGINE

DI–99

LEXUS RX300   (RM785E)

NG

Repair or replace harness or connector.

OK

5

Check voltage between terminals IGT1 – 6 of engine ECU connector and body
ground.

PREPARATION:
Remove the engine ECU with connector still connected (See
page FI–70).
CHECK:
Measure voltage between terminals IGT1 – 6 of the engine
ECU connector and body ground when the engine is cranked.
OK:

Voltage: More than 0.1 V and less than 4.5 V

Reference: INSPECTION USING OSCILLOSCOPE
During cranking or idling, check waveform between terminals
IGT1 – 6 and E1 of the engine ECU connector.
HINT:
Correct waveform appears as shown, with rectangle waves.

NG

Check and replace engine ECU (See page 
IN–32).

OK

6

Disconnect ignition coil with igniter connector, and check voltage between ter-
minals IGT1 – 6 of engine ECU connector and body ground.

PREPARATION:
(a)

Remove the engine ECU with connector still connected
(See page FI–70).

(b)

Disconnect the ignition coil with the igniter connector.

CHECK:
Measure voltage between terminals IGT1 – 6 of the engine
ECU connector and body ground when the engine is cranked.
OK:

Voltage: More than 0.1 V and less than 4.5 V