Toyota FJ Cruiser (GSJ 10, 15 series). Manual — part 50
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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ES
(a) Disconnect the B34 or B36 HO2 sensor connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage between the +B terminal of the HO2
sensor connector and body ground.
Standard Voltage
(d) Turn the ignition switch OFF.
(e) Disconnect the B1 and B2 ECM connectors.
(f)
Check the resistance.
Standard Resistance (Check for open)
Standard Resistance (Check for short)
(g) Reconnect the HO2 sensor connector.
(h) Reconnect the ECM connectors.
17
CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
B36
Wire Harness Side:
Front View
ECM Connector
Bank 1
B34 Bank 2
HO2 Sensor Connector
HT1B or
HT2B
OX1B or
OX2B
+B
E2
HT2B
OX1B
E2
B1
B2
OX2B
HT1B
A116170E04
Terminal Connections
Specified Conditions
+B (B36-2) - Body ground
11 to 14 V
+B (B34-2) - Body ground
Terminal Connections
Specified Conditions
HT1B (B36-1) - HT1B (B1-1)
Below 1
Ω
OX1B (B36-3) - OX1B (B1-18)
E2 (B36-4) - E2 (B1-28)
HT2B (B34-1) - HT2B (B2-5)
OX2B (B34-3) - OX2B (B2-33)
E2 (B34-4) - E2 (B1-28)
Terminal Connections
Specified Conditions
HT1B (B36-1) or HT1B (B1-1) - Body ground
10 k
Ω or higher
OX1B (B36-3) or OX1B (B1-18) - Body ground
HT2B (B34-1) or HT2B (B2-5) - Body ground
OX2B (B34-3) or OX2B (B2-33) - Body ground
ES–156
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
NG
OK
Reference (System Diagram of Bank 1 Sensor 2):
From
Battery
EFI
EFI
Ground
Heater
Sensor
HO2 Sensor
EFI NO. 2
OX1B
E2
MREL
HT1B
OX1B
HT1B
E2
+B
ECM
Duty
Control
A103832E33
REPAIR OR REPLACE HARNESS OR
CONNECTOR
REPLACE HEATED OXYGEN SENSOR (See page
)
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–157
ES
DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim
consists of both the short-term and long-term fuel trims.
The short-term fuel trim is fuel compensation that is used to constantly maintain the air-fuel ratio at
stoichiometric levels. The signal from the Air-Fuel Ratio (A/F) sensor indicates whether the air-fuel ratio is
rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the
air-fuel ratio is rich and an increase in the fuel injection volume if it is lean.
Factors such as individual engine differences, wear over time and changes in operating environment
cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall
fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by
the short- term fuel trim compensation.
If both the short-term and long-term fuel trims are lean or rich beyond predetermined values, it is
interpreted as a malfunction, and the ECM illuminates the MIL and sets a DTC.
HINT:
•
When DTC P0171 or P0174 is set, the actual air-fuel ratio is on the lean side. When DTC P0172 or
P0175 is set, the actual air-fuel ratio is on the rich side.
•
If the vehicle runs out of fuel, the air-fuel ratio is lean and DTC P0171 or P0174 may be set. The MIL is
then illuminated.
•
When the total of the short-term and long-term fuel trim values is within the malfunction threshold (and
the engine coolant temperature is more than 75
°C [167°F]), the system is functioning normally.
DTC
P0171
System Too Lean (Bank 1)
DTC
P0172
System Too Rich (Bank 1)
DTC
P0174
System Too Lean (Bank 2)
DTC
P0175
System Too Rich (Bank 2)
DTC No.
DTC Detection Conditions
Trouble Areas
P0171
P0174
With warm engine and stable air-fuel ratio feedback, fuel trim
considerably in error to lean side (2 trip detection logic)
•
Air induction system
•
Injector blockage
•
Mass Air Flow (MAF) meter
•
Engine Coolant Temperature (ECT) sensor
•
Fuel pressure
•
Gas leakage from exhaust system
•
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
•
A/F sensor (bank 1, 2 sensor 1)
•
A/F sensor heater (bank 1, 2 sensor 1)
•
A/F sensor heater relay
•
A/F sensor heater and A/F sensor heater relay circuits
•
PCV valve and hose
•
PCV hose connections
•
ECM
P0172
P0175
With warm engine and stable air-fuel ratio feedback, fuel trim
considerably in error to rich side (2 trip detection logic)
•
Injector leakage or blockage
•
MAF meter
•
ECT sensor
•
Ignition system
•
Fuel pressure
•
Gas leakage from exhaust system
•
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
•
A/F sensor (bank 1, 2 sensor 1)
•
A/F sensor heater (bank 1, 2 sensor 1)
•
A/F sensor heater relay
•
A/F sensor heater and A/F sensor heater relay circuits
•
ECM
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1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
MONITOR DESCRIPTION
Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the ECM
cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when
there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel
injection volumes also affect the average fuel trim learning value, which is a combination of the average
short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning
value of the air- fuel ratio). If the average fuel trim learning value exceeds the malfunction thresholds, the
ECM interprets this a fault in the fuel system and sets a DTC.
Example:
The average fuel trim learning value is more than +35 % or less than -35 %, the ECM interprets this as a
fuel system malfunction.
MONITOR STRATEGY
Related DTCs
P0171: Fuel trim Lean (bank 1)
P0172: Fuel trim Rich (bank 1)
P0174: Fuel trim Lean (bank 2)
P0175: Fuel trim Rich (bank 2)
Required Sensors/Components (Main)
Fuel system
Required Sensors/Components (Related)
A/F sensor, Mass air flow meter, Crankshaft position sensor
Frequency of Operation
Continuous
Duration
Within 10 seconds
MIL Operation
2 driving cycles
Sequence of Operation
None
Fuel Compensation
Amount
+35%:
Malfunction Threshold
of LEAN Condition
-35%:
Malfunction Threshold
of RICH Condition
1.35
1.0
0.65
P0171, P0174
P0172, P0175
A121607E01
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