Lexus ES300 (2002 year). Manual — part 399
051LT-07
05-30
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DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
183
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
PROBLEM SYMPTOMS TABLE
Symptom
Suspect Area
See page
Engine does not crank (Does not start)
24.Starter
25.Starter relay
No initial combustion (Does not start)
1. ECM power source circuit
2. Fuel pump control circuit
3. ECM
No complete combustion (Does not start)
1. Fuel pump control circuit
Engine cranks normally (Difficult to start)
1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
Cold engine (Difficult to start)
1. Starter signal circuit
2. Fuel pump control circuit
Hot engine (Difficult to start)
1. Starter signal circuit
2. Fuel pump control circuit
High engine idle speed (Poor idling)
1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit
Low engine idle speed (Poor idling)
1. A/C signal circuit (Compressor circuit)
2. Fuel pump control circuit
Rough idling (Poor idling)
1. Compression
2. Fuel pump control circuit
3. Electric throttle control system
Hunting (Poor idling)
1. ECM power source circuit
2. Fuel pump control circuit
Hesitation/Poor acceleration (Poor driveability)
1. Fuel pump control circuit
2. A/T faulty
3. Electric throttle control system
Surging (Poor driveability)
1. Fuel pump control circuit
Soon after starting (Engine stall)
1. Fuel pump control circuit
During A/C operation (Engine stall)
1. A/C signal circuit (Compressor circuit)
2. ECM
Unable to refuel/Difficult to refuel
1. ORVR system
FI6929
A09074
A
B
B+
Power Transistor
Platinum Hot Wire
(Heater)
Output
Voltage
Temperature
sensor
Platinum Hot Wire (Heater)
Temperature sensor
A53295
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DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
05-31
184
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
DTC
P0100
MASS AIR FLOW CIRCUIT MALFUNCTION
CIRCUIT DESCRIPTION
The air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire, tem-
perature sensor and a control circuit installed in a plastic housing. The hot wire air flow meter works on the
principle that the hot wire and temperature sensor located in the intake air bypass of the housing detect any
changes in the intake air temperature.
The hot wire is maintained at the set temperature 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 temperature sensor provide a bridge circuit, with
the power transistor controlled so that the potential of A and B remains equal to maintain the set temperature.
DTC No.
DTC Detecting Condition
Trouble Area
P0100
Open or short in air flow meter circuit with more than 3 sec.
engine speed less than 4,000 rpm
Open or short in air flow meter circuit
Intake air flow meter
ECM
If the ECM detects DTC 0100, it operates the fail-safe function, keeping the ignition timing and injection vol-
ume constantly and making it possible to drive the vehicle.
HINT:
After confirming DTC P0100, use the hand-held tester to confirm the mass air flow ratio from the CURRENT
DATA.
Air Flow Value (g/s)
Malfunction
Approx. 0.0
Air flow meter power source circuit open
VG circuit open or short
160.0 or more
EVG circuit open
051LU-07
A59741
B - G
Battery
FL MAIN
Engine Room J/B
B - W
E.F.I. ECU Relay
Intake Air
Flow Meter
MREL
B - G
1
1
W - B
B - W
E2G
VG
5
3
2
1
6
1K
3
3
1
1B
R
2
2
5
1A
1C
ED
L - W
24
E9
32
E9
8
E6
ECM
E.F.I.
Engine
Room R/B
05-32
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DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
185
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
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 run-
ning or stopped, the engine warmed up or not, the air-fuel ratio lean or rich, etc. at the time of the malfunction.
1
READ VALUE OF OBD II SCAN TOOL OR HAND-HELD TESTER(MAF)
(a)
Read air flow rate on the hand-held tester.
Result:
A
B
Air flow rate (g/s)
0.0
160.0 or more
B
Go to step 5
A
A54396
+B
E2
A53763
E2
VG
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DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
05-33
186
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
2
INSPECT INTAKE AIR FLOW METER SUB-ASSY
(a)
Disconnect the intake air flow meter connector.
(b)
Turn the ignition switch ON.
(c)
Measure voltage between the terminals +B and E2 of the
air flow meter harness side connector.
Voltage: 9 - 14 V
NG
OK
3
INSPECT ECM
(a)
Start the engine.
(b)
Measure voltage between the terminals VG and E2 of the
ECM connector while the engine is idling.
Voltage: 0.5 - 3.0 V
HINT:
The shift position should be P or N and A/C switch should be
turned OFF.
OK
CHECK AND REPLACE ECM
NG
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