Page 713 of 1767
TERMI-
NAL
NO.WIRE
COLORITEM CONDITIONDATA (DC Voltage and
Pulse Signal)
426 BAccelerator position switch
(Idle) ground[Ignition switch ªONº]Approximately 0V
433 R/WAccelerator position sen-
sor power supply[Ignition switch ªONº]Approximately 5V
434 GAccelerator position sen-
sor[Ignition switch ªONº]
IAccelerator pedal fully released0.30 - 0.50V
[Ignition switch ªONº]
IAccelerator pedal fully depressed3.0 - 4.3V
435 L/YAccelerator position switch
(Idle)[Ignition switch ªONº]
IAccelerator pedal fully releasedApproximately 0V
[Ignition switch ªONº]
IAccelerator pedal depressedBATTERY VOLTAGE
(11 - 14V)
439 L/B Tachometer[Engine is running]
IWarm-up condition
IIdle speedApproximately 3.0V
SEF325Y
[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpmApproximately 3.0V
SEF326Y
507 B/W Ignition switch[Ignition switch ªOFFº]0V
[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
TROUBLE DIAGNOSESTD27Ti
ECM Terminals and Reference Value (Cont'd)
EC-351
Page 714 of 1767
Wiring Diagram
YEC141A
TROUBLE DIAGNOSIS FOR POWER SUPPLYTD27Ti
EC-352
Page 715 of 1767

Diagnostic Procedure
INSPECTION START
Start engine.
Is engine running?
Ye s
ENo
CHECK POWER SUPPLY-I.
1. Turn ignition switch to ªONº posi-
tion.
2. Check voltage between ECM
connector terminal
507and
engine ground with
CONSULT-II or voltage tester.
Voltage: Battery voltage
If NG, check the following:
I10A fuse
IHarness for open or short-circuit
between ECM and ignition switch
If NG, replace 10A fuse or repair
harness or connectors.
OK
Go toq
BªCHECK GROUND CIR-
CUITº.
CHECK POWER SUPPLY-II.
1. Stop engine.
2. Check voltage between ECM
connector terminal
325and
engine ground with CON-
SULT-II or voltage tester.
Voltage: Battery voltage
OK
ENG
Check the following:
IECM relay
I20A fuse
IHarness for open or short-circuit
between ECM and battery
IHarness connectors M787, F66
(LHD models)
IBattery connection and charge
If NG, replace fuse or charge bat-
tery or repair harness or connec-
tors.
qA
NEF642
YEC283A
MEC946D
MEC943D
H
H
H
H
TROUBLE DIAGNOSIS FOR POWER SUPPLYTD27Ti
EC-353
Page 716 of 1767

qA
CHECK POWER SUPPLY-III.
1. Turn ignition switch to ªONº position
and then to ªLOCKº position.
2. Check voltage between ECM connector
terminals
107,108,109and engine
ground with CONSULT-II or tester.
Voltage:
After turning ignition switch to
ªLOCKº position, battery voltage
will exist for a few seconds, then
drop to approximately 0V.
NG
EOK
Go toqBªCHECK
GROUND CIRCUITº.
Case-1: Battery voltage does
not exist.
Case-2: Battery voltage exists
for more than a few
seconds.
Case-1
Case-2
EGo toªCHECK ECM
RELAYº.
CHECK HARNESS CONTINUITY
BETWEEN ECM RELAY AND ECM.
1. Disconnect ECM harness connector.
2. Disconnect ECM relay harness connec-
tor.
3. Check harness continuity between
ECM connector terminals
325and
ECM relay connector terminalq
2, and
ECM connector terminals
107,108,
109and ECM relay connector termi-
nalq
5. Refer to wiring diagram.
Continuity should exist.
If OK, check harness for short-circuit.
OK
ENG
Check the following:
IHarness connectors
M787,F66(LHD mod-
els)
IHarness for open or
short-circuit between
ECM relay connector
and ECM connector.
If NG, repair harness or
connectors.
CHECK VOLTAGE BETWEEN ECCS
RELAY AND ENGINE GROUND.
Check voltage between ECM relay con-
nector terminalsq
1,q3and engine ground
with CONSULT-II or tester.
Voltage: Battery voltage
OK
ENG
Check the following:
I20A fuse
IFuse box and battery
connections
IHarness for open or
short-circuit between
ECM relay and battery
If NG, replace fuse or
repair harness or connec-
tors.
CHECK ECM RELAY.
1. Remove ECM relay.
2. Apply 12V direct current between relay
terminalsq
1andq2.
3. Check continuity between relay termi-
nalsq
3andq5.
12V (q
1-q2) applied:
Continuity exists.
No voltage applied:
No continuity
OK
ENG
Replace ECM relay.
qB
MEC944D
MEC945D
NEF350
H
H
H
H
H
TROUBLE DIAGNOSIS FOR POWER SUPPLYTD27Ti
Diagnostic Procedure (Cont'd)
EC-354
Page 717 of 1767
qB
CHECK GROUND CIRCUIT.
1. Turn ignition switch to ªLOCKº position.
2. Disconnect ECM harness connector.
3. Check harness continuity between
ECM connector terminals
104,105,
106and engine ground. Refer to wir-
ing diagram.
Continuity should exist.
If OK, check harness for short-circuit.
OK
ENG
Check the following:
IEngine ground connec-
tions
IHarness for open or
short-circuit between
ECM and engine ground
If NG, repair harness or
connectors.
Check ECM pin terminals for damage and
check the connection of ECM harness
connector.
INSPECTION END
H
H
H
TROUBLE DIAGNOSIS FOR POWER SUPPLYTD27Ti
Diagnostic Procedure (Cont'd)
EC-355
Page 718 of 1767

Component Description
MASS AIR FLOW SENSOR (MAFS)
The mass air flow sensor measures the intake air flow rate by
monitoring a part of the entire flow. Measurements are made by the
ECM which receives electrical signals from the mass air flow sen-
sor which is proportional to the amount of heat emitted from the hot
wire placed in the stream of the intake air.
When intake air flows into the intake manifold through a route
around the hot wire, the heat generated by the hot wire is carried
away by the air flow. The amount of heat detected depends on the
volume of air flow. The temperature of the hot wire is automatically
controlled to maintain it within a finite range regardless of the air
flow rate by regulating the current supplied to the hot wire.
The ECM monitors the air flow by means of the corresponding
electric change.
On Board Diagnosis Logic
DTC Malfunction is detected when...Check Items
(Possible Cause)
P0100
0102IAn excessively high or low voltage from the sensor is
entered to ECM.IHarness or connectors
(The sensor circuit is open or short-circuited.)
IMass air flow sensor
DTC Confirmation Procedure
WITH CONSULT-II
1) Turn ignition switch to ªONº position.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and wait for at least 15 seconds.
WITHOUT CONSULT-II
1) Start engine and wait for at least 15 seconds.
2) Turn ignition switch off, wait for at least 5 seconds and then turn
on.
3) Perform ªDiagnostic Test Mode IIº (Self-diagnostic results).
SEF781K
SEF817Y
DTC P0100 MASS AIR FLOW SENTD27Ti
EC-356
Page 719 of 1767
Wiring Diagram
LHD MODELS
YEC142A
DTC P0100 MASS AIR FLOW SENTD27Ti
EC-357
Page 720 of 1767
RHD MODELS
YEC143A
DTC P0100 MASS AIR FLOW SENTD27Ti
Wiring Diagram (Cont'd)
EC-358