Lexus RX300 (MCU15). Service manual — part 225
A06105
A02330
A10581
ON
FC
DI–132
–
DIAGNOSTICS
ENGINE
LEXUS RX300 (RM785E)
OBD scan tool (excluding hand–held tester):
1
Check operation of fuel pump.
PREPARATION:
(a)
Remove the engine ECU with connector still connected
(See page FI–70).
(b)
Turn the ignition switch ON.
CHECK:
(a)
Connect between terminal FC of the engine ECU connec-
tor and body ground.
(b)
Check that the pulsation damper screw rises up when
connecting between terminal FC of the engine ECU con-
nector and body ground.
OK:
The pulsation damper screw rises up.
OK
Check for starter signal circuit
(See page DI–134).
NG
2
Check for engine ECU power source circuit (See page DI–124).
NG
Repair or replace.
OK
3
Check circuit opening relay (Marking: CIR OPN) (See page FI–57).
NG
Replace circuit opening relay.
OK
A02064
ON
FC
(+)
(–)
–
DIAGNOSTICS
ENGINE
DI–133
LEXUS RX300 (RM785E)
4
Check voltage between terminal FC of engine ECU connector and body ground.
PREPARATION:
(a)
Remove the engine ECU with connector still connected
(See page FI–70).
(b)
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the engine ECU
connector and body ground.
OK:
Voltage: 9 – 14 V
OK
Go to step 5
NG
Check for open in harness and connector between EFI main relay (Marking: EFI) and circuit open-
ing relay, and circuit opening relay and engine ECU.
5
Check fuel pump (See page FI–5).
NG
Repair or replace fuel pump.
OK
6
Check for open in harness and connector between circuit opening relay and fuel
pump, and fuel pump and body ground (See page IN–32).
NG
Repair or replace harness or connector.
OK
Check and replace engine ECU
(See page IN–32).
A05621
From Ignition
Switch
Instrument
Panel J/B
ST
AR
TER
From Battery
Engine Room J/B
MAIN
B–W
W–B
Starter
9
9
B
1
2
3
2
1
6
5
6
9
4
1
1
B
1G
1C
IH1
2A
2I
2D
2D
S2
IE
E9
STARTER Relay
E1
STA
A
J5
7
IH1
19
J/C
1
2
Neutral Start
Switch
B
Engine ECU
B–W
B–W
DI–134
–
DIAGNOSTICS
ENGINE
LEXUS RX300 (RM785E)
Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is therefore
necessary in order to achieve good startability. While the engine is being cranked, the battery positive volt-
age is applied to terminal STA of the engine ECU. The starter signal is mainly used to increase the fuel injec-
tion volume for the starting injection control and after–start injection control.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
This diagnostic chart is based on the premise that the engine is cranked normally. If the engine is not
cranked, proceed to the problem symptoms table on page DI–21.
DI0A7–07
A02045
START
STA
(+)
(–)
–
DIAGNOSTICS
ENGINE
DI–135
LEXUS RX300 (RM785E)
Hand–held tester:
1
Connect hand–held tester, and check STA signal.
PREPARATION:
(a)
Connect the hand–held tester to the DLC3.
(b)
Turn the ignition switch ON and push the hand–held tester main switch ON.
CHECK:
Read the STA signal on the hand–held tester while the starter operates.
OK:
Ignition Switch Position
ON
START
STA Signal
OFF
ON
OK
Proceed to next circuit inspection shown on
problem symptom table (See page DI–21).
NG
2
Check for open in harness and connector between engine ECU and starter relay
(See page IN–32).
NG
Repair or replace harness or connector.
OK
Check and replace engine ECU
(See page IN–32).
OBD scan tool (excluding hand–held tester):
1
Check voltage between terminal STA of engine ECU connector and body ground.
PREPARATION:
Remove the engine ECU with connector still connected (See
page FI–70).
CHECK:
Measure the voltage between terminal STA of the engine ECU
connector and body ground during the engine cranking.
OK:
Voltage: 6 V or more
OK
Proceed to next circuit inspection shown on
problem symptom table (See page DI–21).
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