Lexus RX300 (MCU15). Service manual - part 194

DI–8

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

5.

CHECK FOR INTERMITTENT PROBLEMS

HAND–HELD TESTER only:
By putting the vehicle’s engine ECU in check (test) mode, 1 trip detection logic is possible instead of 2 trip
detection logic and sensitivity to detect open circuits is increased. This makes it easier  to detect intermittent
problems.

(1)

Clear the DTC (See step 3.).

(2)

Set the check (test) mode (See step 3.).

(3)

Perform a simulation test (See page IN–22).

(4)

Check the connector and terminal (See page IN–32).

(5)

Check the visual check and contact pressure (See page IN–32).

(6)

Handle the connector (See page IN–32).

6.

BASIC INSPECTION

When the malfunction code is not confirmed in the DTC check, troubleshooting should be carried out in the
order for all possible circuits to be considered as the causes of the problems. In  many cases, by carrying
out the basic engine check shown in the following flow chart, the location  causing the problem can be found
quickly and efficiently. Therefore, use of this check is essential  in engine troubleshooting.

1

Is battery positive voltage 11V or more when engine is stopped ?

NO

Charge or replace battery.

YES

2

Is engine cranked ?

NO

Proceed to problem table on page DI–21.

YES

3

Does engine start ?

NO

Go to step 7.

YES

P00495

Outside

Inside

A09031

DLC3

SST

Tachometer

9 (TAC)

Battery

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DIAGNOSTICS

ENGINE

DI–9

LEXUS RX300   (RM785E)

4

Check air filter.

PREPARATION:
Remove the air filter.
CHECK:
Visually check that the air filter is not excessively dirty or oily.
HINT:
If necessary, clean the filter with compressed air. First blow from
inside thoroughly, then blow from outside of filter.

NG

Repair or replace.

OK

5

Check engine idle speed.

PREPARATION:
(a)

Warm up engine to normal operating temperature.

(b)

Switch off all accessories.

(c)

Switch off air conditioning.

(d)

Shift transmission into the ”P” position.

(e)

Connect the hand–held tester to DLC3 on the vehicle.

(f)

If you have no hand–held tester, connect tachometer test
prove to terminal 9 (TAC) of DLC3.
SST

09843–18030

(g)

Transit to inspection mode.

NOTICE:
As some tachometer are not compatible with this ignition
system, we recommend that you confirm the compatibility
of your until before use.
CHECK:
Check the idle speed.
OK:

Idle speed: 650 – 750 rpm

NG 

Proceed to problem symptoms table on page
DI–21.

OK

A04438

P12952

A14468

TC

CG

DI–10

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

6

Check ignition timing.

PREPARATION:
(a)

Warm up engine to normal operating temperature.

(b)

Switch off all accessories.

(c)

Switch off air conditioning

(d)

Shift transmission into the ”P” position.

(e)

Using SST, connect terminals 13 (TC) and 4 (CG) of
DLC3.
SST

09843–18040

(f)

Using a timing light, connect the tester to No.1 
high–tension cord.

(g)

Transit to inspection mode.

CHECK:
Check ignition timing.
OK:

Ignition timing: 

10° BTDC at idle

NG

Proceed to page IG–1 and continue to trouble-
shoot.

OK

Proceed to problem symptoms table on page
DI–21.

BE6653
A02330

A10579

–

DIAGNOSTICS

ENGINE

DI–11

LEXUS RX300   (RM785E)

7

Check fuel pressure.

PREPARATION:
(a)

Be sure that enough fuel is in the tank.

(b)

Turn the ignition switch ON.

(c)

Connect the hand–held tester to the DLC3.

(d)

Use ACTIVE TEST mode to operate the fuel pump.

(e)

If you have no hand–held tester, connect the positive (+)
and negative (–) leads from the battery to the fuel pump
connector (See page FI–5 ).

CHECK:
Check that the pulsation damper screw rises up when the fuel
pump operates.

NG

Proceed to page FI–5, and continue to trouble-
shoot.

OK

8

Check for spark.

PREPARATION:
(a)

Remove ignition coil.

(b)

Remove the spark plug.

(c)

Install the spark plug to the ignition coil, and connect the ignition coil connector.

(d)

Disconnect the injector connector.

(e)

Be sure to ground the screw of the spark plug securely.

CHECK:
Check if spark occurs while engine is being cranked.
NOTICE:
To prevent excess fuel being injected from the injectors during this test, don’t crank the engine for
more than 5 – 10 seconds at a time.

NG

Proceed to page IG–1 and continue to trouble-
shoot.

OK

Proceed to problem symptoms table on page
DI–21.