Lexus RX300 (MCU15). Service manual — part 200
DI–32
–
DIAGNOSTICS
ENGINE
LEXUS RX300 (RM785E)
INSPECTION PROCEDURE
HINT:
S
If DTC P0110, P0115, P0120 are output simultaneously, E2 (Sensor Ground) may be open.
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.
1
Connect hand–held tester, and read value of water temperature.
PREPARATION:
(a)
Connect the hand–held tester to the DLC3.
(b)
Turn the ignition switch ON and switch the hand–held tester main switch ON.
CHECK:
Read temperature value on the hand–held tester.
OK:
Same as actual water temperature
HINT:
S
If there is open circuit, Hand–held tester indicates –40
°C (–40°F).
S
If there is short circuit, Hand–held tester indicates 140
°C (284°F) or more.
NG
–40
°C (–40°F)...Go to step 2.
140
°C (284°F) or more...Go to step 4.
OK
Check for intermittent problems (See page
DI–3).
BE6653
A00365
A00366
ON
Engine ECU
2
1
Water Temp. Sensor
Connecting
A02020
ON
Water Temp. Sensor
1
2
THW
E2
Engine ECU
5 V
E1
E2
THW
–
DIAGNOSTICS
ENGINE
DI–33
LEXUS RX300 (RM785E)
2
Check for open in harness or engine ECU.
PREPARATION:
(a)
Disconnect the water temp. sensor connector.
(b)
Connect sensor wire harness terminals together.
(c)
Turn the ignition switch ON.
CHECK:
Read temperature value on the hand–held tester.
OK:
Temperature value: 140°C (284°F) or more
OK
Confirm good connection at sensor. If OK, re-
place water temp. sensor.
NG
3
Check for open in harness or engine ECU.
PREPARATION:
(a)
Remove the engine ECU with connector still connected
(See page FI–70).
(b)
Connect between terminals THW, and E2 of the engine
ECU connector.
HINT:
Water temp. sensor connector is disconnected.
Before checking, do a visual and contact pressure check for the
engine ECU connector (See page IN–32).
(c)
Turn the ignition switch ON.
CHECK:
Read temperature value on the hand–held tester.
OK:
Temperature value: 140°C (284°F) or more
OK
Open in harness between terminals E2 or THW,
repair or replace harness.
NG
Confirm good connection at engine ECU.
If OK, check and replace engine ECU (See
page IN–32).
BE6653
A00372
A00373
ON
2
1
Engine ECU
Water Temp. Sensor
A02043
ON
Water Temp. Sensor
Engine ECU
5 V
E2
THW
E6 Connector
DI–34
–
DIAGNOSTICS
ENGINE
LEXUS RX300 (RM785E)
4
Check for short in harness and engine ECU.
PREPARATION:
(a)
Disconnect the water temp. sensor connector.
(b)
Turn the ignition switch ON.
CHECK:
Read temperature value on the hand–held tester.
OK:
Temperature value: –40°C (–40°F)
OK
Replace water temp. sensor.
NG
5
Check for short in harness or engine ECU.
PREPARATION:
(a)
Remove the engine ECU with connector still connected
(See page FI–70).
(b)
Disconnect the E6 connector of the engine ECU.
HINT:
Water temp. sensor connector is disconnected.
(c)
Turn the ignition switch ON.
CHECK:
Read temperature value on the hand–held tester.
OK:
Temperature value: –40°C (–40°F)
OK
Repair or replace harness or connector.
NG
Check and replace engine ECU (See page
IN–32).
–
DIAGNOSTICS
ENGINE
DI–35
LEXUS RX300 (RM785E)
DTC
P0116
Water Temp. Circuit Range/Performance
Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 onpage DI-31.
DTC No.
DTC Detecting Condition
Trouble Area
If THW < –6.7
°C (20°F), 20 min. or more after starting engine,
engine coolant temp. sensor value is 35
°C (95°F) or less (2
trip detection logic)
P0116
If THW y –6.7
°C (20°F) and < 10°C (50°F), 5 min. or more
after starting engine, engine coolant temp. sensor value is
35
°C (95°F) or less (2 trip detection logic)
S Engine coolant temp. sensor
S Cooling system
If THW y 10
°C (50°F), 2 min. or more after starting engine,
engine coolant temp. sensor value is 35
°C (95°F) or less (2
trip detection logic)
INSPECTION PROCEDURE
HINT:
S
If DTC P0115 and P0116 are output simultaneously, water temp. sensor circuit may be open. Perform
troubleshooting of DTC P0115 first.
S
Read freeze frame data using hand–held tester or OBD scan tool. 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.
1
Are there any other codes (besides DTC P0116) being output?
YES
Go to relevant DTC chart.
NO
2
Check thermostat (See page CO–10).
NG
Replace thermostat.
OK
Replace engine coolant temp. sensor.
DI6UZ–04
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