Nissan Silvia. Instruction — part 147
4
CHECK POWER SUPPLY
1. Disconnect mass air flow sensor harness connector.
SEC378C
2. Turn ignition switch “ON”.
3. Check voltage between terminal 3 and ground with CONSULT-II or tester.
SEC408C
OK or NG
OK
©
GO TO 6.
NG
©
GO TO 5.
5
DETECT MALFUNCTIONING PART
Check the following.
I
Harness for open or short between ECM relay and mass air flow sensor
I
Harness for open or short between mass air flow sensor and ECM
©
Repair harness or connectors.
6
CHECK GROUND CIRCUIT
1. Turn ignition switch “OFF”.
2. Disconnect ECM harness connector.
3. Check harness continuity between mass air flow sensor terminal 2 and ECM terminal 17.
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 7.
NG
©
Repair open circuit or short to ground or short to power in harness or connectors.
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DTC 0102 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure (Cont’d)
EC-103
7
CHECK INPUT SIGNAL CIRCUIT
1. Check harness continuity between mass air flow sensor terminal 1 and ECM terminal 16.
Refer to wiring diagram.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK
©
GO TO 8.
NG
©
Repair open circuit or short to ground or short to power in harness or connectors.
8
CHECK MASS AIR FLOW SENSOR
Refer to “Component Inspection”, EC-104.
OK or NG
OK
©
GO TO 9.
NG
©
Replace mass air flow sensor.
9
CHECK INTERMITTENT INCIDENT
Perform “TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT”, EC-82.
©
INSPECTION END
SEC409C
SEF977P
Component Inspection
NMEC0679
MASS AIR FLOW SENSOR
NMEC0679S01
1.
Turn ignition switch “ON”.
2.
Start engine and warm it up to normal operating temperature.
3.
Check voltage between ECM terminal 16 (Mass air flow sen-
sor signal) and ground.
Conditions
Voltage V
Ignition switch “ON” (Engine stopped.)
Less than 1.2
Idle (Engine is warmed-up to normal operating
temperature.)
0.8 - 1.5
3,000 rpm (Engine is warmed-up to normal oper-
ating temperature.)
1.4 - 2.0
Idle to about 4,000 rpm*
0.8 - 1.5 to Approx. 4.0
*: Check for linear voltage rise in response to increases to about 4,000 rpm in
engine speed.
4.
If the voltage is out of specification, disconnect mass air flow
sensor harness connector and connect it again. Repeat above
check.
5.
If NG, remove mass air flow sensor from air duct. Check hot
wire for damage or dust.
DTC 0102 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure (Cont’d)
EC-104
SEF594K
Component Description
NMEC0680
The engine coolant temperature sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the
engine coolant temperature input. The sensor uses a thermistor
which is sensitive to the change in temperature. The electrical
resistance of the thermistor decreases as temperature increases.
SEF012P
<Reference data>
Engine coolant temperature
°C (°F)
Voltage*
mV
Resistance
k
Ω
−10 (14)
222
7.0 - 11.4
20 (68)
176
2.1 - 2.9
50 (122)
114
0.68 - 1.00
90 (194)
47
0.236 - 0.260
110 (230)
32
0.143 - 0.153
150 (302)
16
0.050 - 0.065
*: These data are reference values and are measured between ECM terminal 18
(Engine coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM’s
transistor. Use a ground other than ECM terminals, such as
the ground.
CONSULT-II Reference Value in Data Monitor
Mode
NMEC0681
MONITOR ITEM
CONDITION
SPECIFICATION
COOLAN TEMP/S
I
Engine: After warming up
More than 70°C (158°F)
On Board Diagnosis Logic
NMEC0682
DTC No.
Malfunction is detected when ...
Check Items (Possible Cause)
0103
I
An excessively high or low voltage from the sensor is
sent to ECM.*
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Engine coolant temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
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DTC 0103 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Component Description
EC-105
Fail-safe Mode
NMEC0683
Detected items
Engine operating condition in fail-safe mode
Engine coolant tempera-
ture sensor circuit
Engine coolant temperature will be determined by ECM based on the time after turning ignition switch
“ON” or “START”.
CONSULT-II displays the engine coolant temperature decided by ECM.
Condition
Engine coolant temperature decided (CONSULT-II
display)
Just as ignition switch is turned ON or Start
20°C (68°F)
More than approx. 6 minutes after ignition ON or
Start
80°C (176°F)
Except as shown above
20 - 80°C (68 - 176°F)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates
while the engine is running.
SEF013Y
DTC Confirmation Procedure
NMEC0684
NOTE:
If “DTC Confirmation Procedure” has been previously conducted,
always turn ignition switch “OFF” and wait at least 5 seconds
before conducting the next test.
With CONSULT-II
1)
Turn ignition switch “ON”.
2)
Select “DATA MONITOR” mode with CONSULT-II.
3)
Wait at least 5 seconds.
4)
If DTC is detected, go to “Diagnostic Procedure”, EC-108 .
Without CONSULT-II
1)
Turn ignition switch “ON” and wait at least 5 seconds.
2)
Turn ignition switch “OFF”, wait at least 5 seconds and then
turn “ON”.
3)
Perform “Diagnostic Test Mode II (Self-diagnostic results)” with
ECM.
4)
If DTC is detected, go to “Diagnostic Procedure”, EC-108.
DTC 0103 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Fail-safe Mode
EC-106
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