apexdtec.pdf
(
367 KB
)
Pobierz
Appendix D
Technical Reference & Specifications
Diagnostic Tester
Fig. D-1
TL874fD01
D-1
Engine Control Systems II - Course 874
Appendix D
DIAGNOSTIC REFERENCE INFORMATION
Vane Air Flow Meter (Vs)
Circuit
Description
The vane air flow meter is located in the intake air duct between the air
cleaner housing and the engine throttle body. It provides the ECM
information on the amount of load placed on the engine by directly
measuring intake air volume.
During engine operation, intake air flow reacts against the meter’s
measuring plate, which causes it to deflect in proportion to the volume
of air flow. This movement is transferred through a shaft to a movable
arm on the meter’s potentiometer (variable resistor). The Vs signal to
ECM varies according to the potentiometer’s position.
The vane air flow meter also houses the intake air temperature sensor
and a fuel pump switch. The fuel pump switch is used to maintain fuel
pump operation after start-up (when sufficient air flow exists to open
the measuring plate).
Vane
Air Flow Meter
As shown in the graph, Vs
signal voltage decreases with
higher air flow (larger
measuring plate opening). The
Vc - E2 line represents the 5V
reference source.
E
2
Vc
The Vs signal represents
the amount of load
placed on the engine.
The potentiometer
provides a variable
voltage signal back to
the Vs terminal of the
ECM.
5.0
Vs
E
2
NOTE: The 22R-E and 4A-GE
engines use an air flow meter
with opposite voltage logic.
0
Measuring Plate Opening
ECM
Air Flow Meter
Vc
Vc
5VVc
r
1
R
1
Vs
r
2
Vs
Microcomputer
R
2
E
2
E
2
E
1
Pump Switch
E
1
Fig. D-2
TL874fD02
D-2
TOYOTA Technical Training
Technical Reference & Specifications
Troubleshooting
Hints
• The air flow meter is provided a regulated 5V reference at Vc terminal.
• As indicated in the graph, the voltage reading at Vs terminal with
Ignition ON, Engine OFF should be between 3.7V - 4.3V.
• Once the engine is started, Vs signal voltage should decrease to
indicate initial measuring plate opening.
• The r
2
resistor (which is connected in parallel to the r
1
) allows the
meter to continue to provide a Vs signal in the event an open occurs
in the main potentiometer (r
1
).
• The R
1
and R
2
resistors provide the ECM with self-diagnostic
capabilities and also provides a fail-safe voltage in the event of an
open circuit.
OBD Diagnostic
Trouble Codes
DTC #
Effected Circuit
Diagnostic Trouble Code Detection Condition
31
Vs Circuit
Open or Short (Vc) in Air Flow Meter Circuit for Specified Time
Open or Short (Vc – Vs) in Air Flow Meter Circuit
for Specified Time
32
Vs Circuit
OBD II
Diagnostic
Trouble Codes
DTC #
Effected Circuit
Diagnostic Trouble Code Detection Condition
Air Flow Meter
Circuit
P0100
Air Flow Meter Circuit Malfunction
Air Flow Meter
Circuit
P0101
Air Flow Meter Circuit Range/Performance Problem
Typical Serial
Data
Units
Data Source
Name
Warm Idle
2.5V ± 0.5V
1
OBD
Vs
volts
____________
____________
____________
OBDII
2.5V ± 0.5V
1
V-BoB
Vs
volts
1. 3VZ-FE = 2.8V ± 0.6V
D-3
Engine Control Systems II - Course 874
Appendix D
DIAGNOSTIC REFERENCE INFORMATION
Karman Vortex Air Flow Meter (Ks)
Circuit
Description
Like the vane air flow meter, the Karman Vortex Air Flow Meter is
located between the air cleaner housing and the engine's throttle body.
It also provides the ECM with the same type of information; an intake
air volume signal that is used to determine the amount of load placed
on the engine.
The operation of the Karman Vortex Air Flow Meter differs from that of
the vane type. During engine operation, a swirling effect is created in
the intake air stream when it reacts against the meter's vortex
generator. A sample of this pulsating air is then applied to a movable
metal foil mirror, which causes it to flutter. The oscillating mirror causes
light from the photo coupler's LED to be alternately applied and diverted
from a phototransistor.
As a result, the phototransistor rapidly switches the 5V Ks signal to the
ECM. As shown in the diagram, the frequency of the Ks signal increases
proportionally with intake air flow.
Karman Vortex
Air Flow Meter
As shown in the
diagram, the Ks
5V square wave
signal increases in
frequency with
higher intake air
volume.
High
Inside the Karman
Vortex air flow meter,
intake airflow oscillates
a movable mirror which
turns a light sensitive
photo transistor
on and off.
Voltage
Signal (Ks)
Volts
Low
Time
Low
High
Air Flow Meter
ECU
5VVc
Vc
Vc
Ks
Ks
E
2
E
2
Fig. D-3
TL874fD03
D-4
TOYOTA Technical Training
Technical Reference & Specifications
Troubleshooting
Hints
• Remember a 5V signal operating at a 50% duty cycle will read
approximately 2.5V. Since Ks operates at approximately 50% duty
cycle during engine operation, Ks signal voltage will provide little
useful information during diagnosis.
• Ks signal frequency changes dramatically with engine load changes.
For this reason, observing Ks frequency changes would provide the
most useful diagnostic information. Accurate Ks signal inspection
requires using an oscilloscope or high quality digital multimeter with
frequency capabilities (non-OBD vehicles).
OBD Diagnostic
Trouble Codes
DTC #
Effected Circuit
Diagnostic Trouble Code Detection Condition
31
Ks Circuit
Open or Short in Air Flow Meter Circuit for Specified Time
OBD II
Diagnostic
Trouble Codes
DTC #
Effected Circuit
Diagnostic Trouble Code Detection Condition
Air Flow Meter
Circuit
P0100
Air Flow Meter Circuit Malfunction
Air Flow Meter
Circuit
P0101
Air Flow Meter Circuit Range/Performance Problem
Typical Serial
Data
Data Source
Name
Units
Warm Idle
OBD
Ks
ms
40ms ± 15ms
____________
____________
____________
OBDII
V-BoB
Ks
ms
40ms ± 15ms
D-5
Engine Control Systems II - Course 874
Plik z chomika:
j_czaja1
Inne pliki z tego folderu:
apexftec.pdf
(2156 KB)
evaporat.pdf
(1615 KB)
apexaglo.pdf
(76 KB)
o2andafs.pdf
(969 KB)
diagnost.pdf
(950 KB)
Inne foldery tego chomika:
01 Toyota Prius
2007 Yaris Manual
2007 Yaris Manual 112
Documentos Toyota Avensis.rar
Manuales_de_taller_Toyota_Land_Cruiser_Hdj80(1).rar
Zgłoś jeśli
naruszono regulamin