Nissan Silvia. Instruction — part 162
Wiring Diagram
=NMEC0741
TEC807
GI
MA
EM
LC
FE
CL
MT
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
VEHICLE SPEED SENSOR (VSS)
Wiring Diagram
EC-163
Diagnostic Procedure
NMEC0742
1
INSPECTION START
Do you have CONSULT-II?
Yes or No
Yes
©
GO TO 2.
No
©
GO TO 3.
2
CHECK OVERALL FUNCTION
With CONSULT-II
1. Turn ignition switch “OFF”.
2. Lift up the vehicle.
3. Start engine and let it idle.
4. Select “VHCL SPEED SE” in “DATA MONITOR” mode with CONSULT-II.
5. Check “VHCL SPEED SE” indication when rotating wheels with suitable gear position.
SEC421C
OK or NG
OK
©
INSPECTION END
NG
©
GO TO 4.
3
CHECK OVERALL FUNCTION
Without CONSULT-II
1. Turn ignition switch “OFF”.
2. Lift up the vehicle.
3. Start engine and let it idle.
4. Read the voltage signal between ECM terminal 32 and ground with an oscilloscope.
5. Verify that the oscilloscope screen shows a signal wave as shown below under the following conditions.
SEC422C
OK or NG
OK
©
INSPECTION END
NG
©
GO TO 4.
VEHICLE SPEED SENSOR (VSS)
Diagnostic Procedure
EC-164
4
CHECK VEHICLE SPEED SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch “OFF”.
2. Disconnect ECM harness connector and combination meter harness connector.
3. Check harness continuity between ECM terminal 32 and combination meter terminal 31.
Refer to Wiring Diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK
©
GO TO 6.
NG
©
GO TO 5.
5
DETECT MALFUNCTIONING PART
Check the following.
I
Harness connectors F4, M60
I
Harness for open or short between ECM and combination meter
©
Repair open circuit or short to ground or short to power in harness or connectors.
6
CHECK SPEEDOMETER FUNCTION
Make sure that speedometer functions properly.
OK or NG
OK
©
GO TO 8.
NG
©
GO TO 7.
7
CHECK SPEEDOMETER CIRCUIT FOR OPEN AND SHORT
Check the following.
I
Harness connectors F4, M60
I
Harness for open or short between combination meter and ABS control unit
OK or NG
OK
©
Check combination meter and vehicle speed sensor. Refer to EL section.
NG
©
Repair open circuit or short to ground or short to power in harness or connectors.
8
CHECK INTERMITTENT INCIDENT
Refer to “TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT”, EC-82.
©
INSPECTION END
GI
MA
EM
LC
FE
CL
MT
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
VEHICLE SPEED SENSOR (VSS)
Diagnostic Procedure (Cont’d)
EC-165
Description
NMEC0743
SYSTEM DESCRIPTION
NMEC0743S01
Sensor
Input Signal to ECM
ECM func-
tion
Actuator
Camshaft position sensor
Engine speed
Idle air
control
IACV-AAC valve
Mass air flow sensor
Amount of intake air
Engine coolant temperature sensor
Engine coolant temperature
Ignition switch
Start signal
Throttle position sensor
Throttle position
Park/Neutral position switch
Park/Neutral position
Air conditioner switch
Air conditioner operation
Power steering oil pressure switch
Power steering load signal
Battery
Battery voltage
Vehicle speed sensor
Vehicle speed
This system automatically controls engine idle speed to a specified
level. Idle speed is controlled through fine adjustment of the
amount of air which bypasses the throttle valve via IACV-AAC
valve. The IACV-AAC valve repeats ON/OFF operation according
to the signal sent from the ECM. The camshaft position sensor
detects the actual engine speed and sends a signal to the ECM.
The ECM then controls the ON/OFF time of the IACV-AAC valve
so that engine speed coincides with the target value memorized in
ECM. The target engine speed is the lowest speed at which the
engine can operate steadily. The optimum value stored in the ECM
is determined by taking into consideration various engine
conditions, such as during warm up, deceleration, and engine load
(air conditioner and power steering).
SEF040E
COMPONENT DESCRIPTION
NMEC0743S02
IACV-AAC Valve
NMEC0743S0201
The IACV-AAC valve is moved by ON/OFF pulses from the ECM.
The longer the ON pulse, the greater the amount of air that will flow
through the valve. The more air that flows through the valve, the
higher the idle speed.
CONSULT-II Reference Value in Data Monitor
Mode
NMEC0744
Specification data are reference values.
MONITOR ITEM
CONDITION
SPECIFICATION
IACV-AAC/V
I
Engine: After warming up
I
Air conditioner switch: “OFF”
I
Shift lever: “N”
I
No-load
Idle
20 - 40%
2,000 rpm
—
IDLE AIR CONTROL VALVE (IACV) — AUXILIARY AIR CONTROL (AAC) VALVE
Description
EC-166
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