Page 1105 of 3051

Fail-safe ModeNLEC1385
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuitEngine speed will not rise more than 2,400 rpm due to the fuel
cut.
DTC Confirmation ProcedureNLEC1386CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
SEF058Y
PROCEDURE FOR MALFUNCTION ANLEC1386S01With CONSULT-II
1) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 2 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-684.
With GST
Follow the procedure ªWith CONSULT-IIº above.
No Tools
1) Turn ignition switch ªONº, and wait at least 2 seconds.
2) Turn ignition switch ªOFFº, wait at least 10 seconds and then
turn ªONº.
3) Perform ªDiagnostic Test Mode II (Self-diagnostic results)º with
ECM.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-684.
SEF058Y
PROCEDURE FOR MALFUNCTION BNLEC1386S02With CONSULT-II
1) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and wait 2 seconds at most.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-684.
With GST
Follow the procedure ªWith CONSULT-IIº above.
No Tools
1) Start engine and wait 2 seconds at most.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Fail-safe Mode
EC-680
Page 1106 of 3051
2) Turn ignition switch ªOFFº, wait at least 10 seconds and then
turn ªONº.
3) Perform ªDiagnostic Test Mode II (Self-diagnostic results)º with
ECM.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-684.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
DTC Confirmation Procedure (Cont'd)
EC-681
Page 1107 of 3051
Wiring DiagramNLEC1387MODELS WITH ECM IN ENGINE COMPARTMENTNLEC1387S01
YEC687
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Wiring Diagram
EC-682
Page 1108 of 3051
MODELS WITH ECM IN CABINNLEC1387S02
YEC912
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Wiring Diagram (Cont'd)
EC-683
Page 1109 of 3051
Diagnostic ProcedureNLEC1388
1 INSPECTION START
Which malfunction (A, or B) is duplicated?
Malfunction A or B
A©GO TO 3.
B©GO TO 2.
2 CHECK INTAKE SYSTEM
Check the following for connection.
+Air duct
+Vacuum hoses
+Intake air passage between air duct to collector
OK or NG
OK©GO TO 3.
NG©Reconnect the parts.
3 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF202X
©GO TO 4.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Diagnostic Procedure
EC-684
Page 1110 of 3051

4 CHECK POWER SUPPLY
1. Disconnect mass air flow sensor harness connector.
SEF772Z
2. Turn ignition switch ªONº.
3. Check voltage between terminal 2, 4 and ground with CONSULT-II or tester.
SEF297X
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 DETECT MALFUNCTIONING PART
Check the following.
+Joint connector-3 (where fitted)
+Joint connector F46 (where fitted)
+Harness for open or short between ECM relay and mass air flow sensor
+Harness for open or short between mass air flow sensor and ECM
©Repair harness or connectors.
6 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between mass air flow sensor terminal 3 and ECM terminal 73.
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.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Diagnostic Procedure (Cont'd)
EC-685
Page 1111 of 3051

7 CHECK INPUT SIGNAL CIRCUIT
1. Check harness continuity between mass air flow sensor terminal 1 and ECM terminal 61.
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 ªComponent Inspectionº, EC-686.
OK or NG
OK©GO TO 9.
NG©Replace mass air flow sensor.
9 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-670.
©INSPECTION END
SEF993W
SEF987W
Component InspectionNLEC1389MASS AIR FLOW SENSORNLEC1389S011. Turn ignition switch ªONº.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 61 (Mass air flow sen-
sor signal) and ground.
Conditions Voltage V
Ignition switch ªONº (Engine stopped.) Less than 1.2
Idle (Engine is warmed-up to normal operating
temperature.)1.3 - 1.7
2,500 rpm (Engine is warmed-up to normal oper-
ating temperature.)1.8 - 2.4
Idle to about 4,000 rpm* 1.3 - 1.7 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
film for damage or dust.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Diagnostic Procedure (Cont'd)
EC-686
Page 1112 of 3051

SEF206T
Component DescriptionNLEC1390MODELS WITH INTAKE AIR TEMPERATURE SENSOR
ON INTAKE AIR DUCT
NLEC1390S01The intake air temperature sensor is mounted to the air duct hous-
ing. The sensor detects intake air temperature and transmits a sig-
nal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive
to the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.
SEF012P
Intake air temperature
ÉC (ÉF)Voltage*
VResistance
kW
20 (68) 3.5 2.1 - 2.9
80 (176) 1.23 0.27 - 0.38
*: These data are reference values and are measured between ECM terminal 64
(Intake air 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.
NEF306A
MODELS WITH INTAKE AIR TEMPERATURE SENSOR
IN MASS AIR FLOW SENSOR
NLEC1390S02The intake air temperature sensor is built into mass air flow sen-
sor. The sensor detects intake air temperature and transmits a sig-
nal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive
to the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.
SEF012P
Intake air temperature
ÉC (ÉF)Voltage*
VResistance
kW
20 (68) 3.5 2.1 - 2.9
80 (176) 1.23 0.27 - 0.38
*: These data are reference values and are measured between ECM terminal 64
(Intake air temperature sensor) and ground.
DTC P0110 INTAKE AIR TEMPERATURE SENSORSR20DE
Component Description
EC-687