Toyota FJ Cruiser (GSJ 10, 15 series). Instruction — part 35
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–95
ES
DESCRIPTION
The Mass Air Flow (MAF) meter is a sensor that measures the amount of air flowing through the throttle
valve.
The ECM uses this information to determine the fuel injection time and to provide appropriate air-fuel
ratio.
Inside the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air.
By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of
incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a
constant current value, the ECM varies the voltage applied to these components in the MAF meter. The
voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake
air volume.
The circuit is constructed so that the platinum hot wire and the temperature sensor provide a bridge
circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the
predetermined temperature.
HINT:
When any of these DTCs are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition
timing is calculated by the ECM, according to the engine RPM and throttle valve position. Fail-safe mode
continues until a pass condition is detected.
DTC
P0100
Mass or Volume Air Flow Circuit
DTC
P0102
Mass or Volume Air Flow Circuit Low Input
DTC
P0103
Mass or Volume Air Flow Circuit High Input
DTC No.
DTC Detection Conditions
Trouble Areas
P0100
Open or short in Mass Air Flow (MAF) meter circuit for 3
seconds
(1 trip detection logic)
•
Open or short in MAF meter circuit
•
MAF meter
•
ECM
P0102
Open in Mass Air Flow (MAF) meter circuit for 3 seconds
(1 trip detection logic)
•
Open in MAF meter circuit
•
Short in ground circuit
•
MAF meter
•
ECM
P0103
Short in Mass Air Flow (MAF) meter circuit for 3 seconds
(1 trip detection logic)
•
Short in MAF meter circuit (+B circuit)
•
MAF meter
•
ECM
Temperature Sensor
(Thermistor)
Temperature Sensor (Thermistor)
Power Transistor
Piatinum Hot Wire
Piatinum Hot Wire (Heater)
Output Voltage
+B
B
A
A115747E01
ES–96
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
HINT:
When any of these DTCs are set, check the air-flow rate by selecting the following menu items on an
intelligent tester: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF.
MONITOR DESCRIPTION
If there is a defect in the MAF meter or an open or short circuit, the voltage level deviates from the normal
operating range. The ECM interprets this deviation as a malfunction in the MAF meter and sets a DTC.
Example:
When the sensor voltage output remains less than 0.2 V, or more than 4.9 V, for more than 3 seconds, the
ECM sets a DTC.
If the malfunction is not repaired successfully, a DTC is set 3 seconds after the engine is next started.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
P0100:
P0102:
P0103:
COMPONENT OPERATING RANGE
Mass Air Flow Rate (g/sec)
Malfunctions
Approximately 0.0
•
Open in Mass Air Flow (MAF) meter power source circuit
•
Open or short in VG circuit
271.0 or more
•
Open in EVG circuit
Related DTCs
P0100: Mass air flow meter range check (Fluctuating)
P0102: Mass air flow meter range check (Low voltage)
P0103: Mass air flow meter range check (High voltage)
Required Sensors/Components (Main)
MAF meter
Required Sensors/Components (Related)
Crankshaft position sensor
Frequency of Operation
Continuous
Duration
3 seconds
MIL Operation
Immediate: Engine RPM less than 4,000 rpm
2 driving cycles: Engine RPM 4,000 rpm or more
Sequence of Operation
None
Monitor runs whenever following DTCs not present
None
Mass air flow meter voltage
Less than 0.2 V or more than 4.9 V
Mass air flow meter voltage
Less than 0.2 V
Mass air flow meter voltage
More than 4.9 V
Mass air flow meter voltage
Between 0.2 V and 4.9 V
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–97
ES
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was
moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other
data, from the time the malfunction occurred.
(a) Connect an intelligent tester to the DLC3.
(b) Start the engine.
(c) Turn the tester ON.
(d) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DATA LIST / PRIMARY / MAF.
(e) Read the values displayed on the tester.
Result
1
READ VALUE USING INTELLIGENT TESTER (MASS AIR FLOW RATE)
Battery
EFI
EFI
EFI No. 2
ECM
VG
E2G
MREL
Mass Air Flow Meter
3
1
5
2
1
3
2
1
2
2
1
E47
8
B1
B1
30
29
B13
A133457E01
Mass Air Flow Rate (g/sec)
Proceed to
0.0
A
ES–98
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
*
1: The value must be changed when the throttle valve is
open or closed.
B
C
A
(a) Disconnect the B13 Mass Air Flow (MAF) meter
connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage between the terminal of the wire
harness side connector and body ground.
Standard Voltage
(d) Reconnect the MAF meter connector.
NG
OK
(a) Start the engine.
(b) Measure the voltage between the terminals of the B1
ECM connector.
HINT:
The transmission gear selector lever should be in the P
or N position and the A/C switch should be turned OFF.
Standard Voltage
OK
NG
271.0 or more
B
Between 1.0 and 270.0 (
*
1)
C
Mass Air Flow Rate (g/sec)
Proceed to
Go to step 6
CHECK FOR INTERMITTENT PROBLEMS
2
INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)
5
4
3
2
1
Front View
Wire Harness Side:
MAF Meter Connector
B13
+B
A107942E07
Tester Connections
Specified Conditions
+B (B13-1) - Body ground
11 to 14 V
Go to step 5
3
INSPECT ECM (VG VOLTAGE)
VG (+)
ECM Connector
B1
E2G (-)
A115970E16
Tester Connections
Conditions
Specified Conditions
VG (B1-30) - E2G (B1-29)
Engine idling
0.5 to 3.0 V
REPLACE ECM (See page
)
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