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MPI -Troubleshooting13A-114
CHECK CHART FOR RESISTANCE AND CONTINUITY
BETWEEN TERMINALS
1. Turn the ignition switch to “LOCK” (OFF) position.
2. Disconnect the engine-ECU connector.
3. Measure the resistance and check for continuity between
the terminals of the engine-ECU harness-side connector
while referring to the check chart.
NOTE
(1) When measuring resistance and checking continuity,
a harness for checking contact pin pressure should
be used instead of inserting a test probe.
(2) Checking need not be carried out in the order given
in the chart.
Caution
If the terminals that should be checked are mistaken,
or if connector terminals are not correctly shorted
to earth, damage may be caused to the vehicle wiring,
sensors, engine-ECU and/or ohmmeter.
Be careful to prevent this!
4. If the ohmmeter shows any deviation from the standard
value, check the corresponding sensor, actuator and
related electrical wiring, and then repair or replace.
5. After repair or replacement, recheck with the ohmmeter
to confirm that the repair or replacement has corrected
the problem.
Engine-ECU Harness Side Connector Terminal Arrangement
Terminal No.Inspection itemNormal condition (Check condition)
1-12No. 1 injector2-3Ω(at 20_C)
14 - 12No. 2 injector
2-12No. 3 injector
15 - 12No. 4 injector
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MPI -Troubleshooting13A-115
Terminal No. Normal condition (Check condition)Inspection item
3-12Fuel pressure control solenoid valve28 - 36Ω(at 20_C)
4-12Stepper motor coil (A1)28 - 33Ω(at 20_C)
17 - 12Stepper motor coil (A2)
5-12Stepper motor coil (B1)
18 - 12Stepper motor coil (B2)
6-12EGR control solenoid valve36 - 44Ω(at 20_C)
9-12Purge control solenoid valve22 - 26Ω(at 20_C)
11 - 1 2Waste gate solenoid valve62 - 74Ω(at 20_C)
13 - Body earthENGINE-ECU earthContinuity (0Ω)
26 - Body earthENGINE-ECU earth
53 - 12Secondary air control solenoid valve28 - 36Ω(at 20_C)
54 - 12Oxygen sensor heater (Rear)11 - 1 8Ω(at 20_C)
60 - 12Oxygen sensor heater (Front)4.5 - 8.0Ω(at 20_C)
72 - 92Intake air temperature sensor13 - 17 kΩ(When intake air temperature is - 20_C)
5.7 - 6.7 kΩ(When intake air temperature is 0_C)
2.3 - 3.0 kΩ(When intake air temperature is 20_C)
1.0 - 1.5 kΩ(When intake air temperature is 40_C)
0.56 - 0.76 kΩ(When intake air temperature is 60_C)
0.30 - 0.42 kΩ(When intake air temperature is 80_C)
83 - 92Engine coolant temperature sensor14 - 17 kΩ(When coolant temperature is - 20_C)
5.1 - 6.5 kΩ(When coolant temperature is 0_C)
2.1 - 2.7 kΩ(When coolant temperature is 20_C)
0.9 - 1.3 kΩ(When coolant temperature is 40_C)
0.48 - 0.68 kΩ(When coolant temperature is 60_C)
0.26 - 0.36 kΩ(When coolant temperature is 80_C)
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MPI -Troubleshooting13A-116
INSPECTION PROCEDURE USING AN
ANALYZER
AIR FLOW SENSOR
Measurement Method
1. Disconnect the air flow sensor connector, and connect
the special tool (test harness: MB991709) in between.
(All terminals should be connected.)
2. Connect the analyzer special patterns pickup to air flow
sensor connector terminal No. 3.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 65.
Standard Wave Pattern
Observation conditions
FunctionSpecial patterns
Pattern heightLow
Pattern selectorDisplay
Engine r/minIdle speed
Standard wave pattern
(V)
10
0The time (cycle time) T is reduced when
the amount of intake air increases.
Times T1 and T2 are equal.
Time T
T1 T2
Observation conditions (from conditions above engine speed is increased by racing.)
Time (V)
10
0T
Wave Pattern Observation Points
Check that cycle time T becomes shorter and the frequency increases when the engine speed is increased.
Analyzer
Special
patterns
pickup
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MPI -Troubleshooting13A-117
Examples of Abnormal Wave Patterns
DExample 1
Cause of problem
Sensor interface malfunction
Wave pattern characteristics
Rectangular wave pattern is output even when the engine
is not started.
DExample 2
Cause of problem
Damaged rectifier or vortex generation column
Wave pattern characteristics
Unstable wave pattern with non-uniform frequency.
However, when an ignition leak occurs during acceleration,
the wave pattern will be distorted temporarily, even if the air
flow sensor is normal.
CAMSHAFT POSITION SENSOR AND CRANK ANGLE
SENSOR
Measurement Method
1. Disconnect the camshaft position sensor connector and
connect the special tool (test harness: MB991709) in
between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to camshaft
position sensor terminal No. 2.
3. Disconnect the crank angle sensor connector and connect
the special tool (test harness: MD998478) in between.
4. Connect the analyzer special patterns pickup to crank
angle sensor terminal No. 2.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 88. (When checking the
camshaft position sensor signal wave pattern.)
2. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 89. (When checking the crank
angle sensor signal wave pattern.)
Crank angle
sensor connector
Camshaft position sensor
connectorAnalyzer
Special patterns
pick-up
Page 650 of 1449
MPI -Troubleshooting13A-118
Standard Wave Pattern
Observation condition
FunctionSpecial patterns
Pattern heightLow
Pattern selectorDisplay
Engine r/minIdle speed
Standard Wave Pattern
Crank angle
sensor output
wave pattern(V)
75_BTDC2 engine revolutions
(1 camshaft revolution)
5_BTDCThe time (cycle time) T is
reduced when the engine
speed increases
0
Camshaft position
sensor output
wave pattern
TDC: Top dead centre131_49_
No. 1 TDC No. 3 TDC No. 4 TDC No. 2 TDCTime
056_34_
Wave Pattern Observation Points
Check that cycle time T becomes shorter when the engine speed increases.
Examples of Abnormal Wave Patterns
DExample 1
Cause of problem
Sensor interface malfunction
Wave pattern characteristics
Rectangular wave pattern is output even when the engine
is not started.
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MPI -Troubleshooting13A-119
DExample 2
Cause of problem
Loose timing belt
Abnormality in sensor disk
Wave pattern characteristics
Wave pattern is displaced to the left or right.
INJECTOR
Measurement Method
1. Disconnect the injector connector, and then connect the
special tool (test harness: MB991348) in between.
(All terminals should be connected.)
2. Connect the analyzer special patterns pickup to terminal
No. 2 of the injector connector.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 1. (When checking the No. 1
cylinder.)
2. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 14. (When checking the No.
2 cylinder.)
3. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 2. (When checking the No. 3
cylinder.)
4. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 15. (When checking the No.
4 cylinder.)
Standard Wave Pattern
Observation conditions
FunctionSpecial patterns
Pattern heightVariable
Variable knobAdjust while viewing the wave pattern
Pattern selectorDisplay
Engine r/minIdle speed
Special
patterns
pickupAnalyzer
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MPI -Troubleshooting13A-120
Standard wave pattern
(V)
Point A
Point BSolenoid back electromotive force
(Approx. 7×10 V)
Injector drive time
Power voltage
Drive signal: ON Drive signal: OFF
Time 50
0
Wave Pattern Observation Points
Point A: Height of solenoid back electromotive force
Contrast with standard wave patternProbable cause
Solenoid coil back electromotive force is low or doesn’t
appear at all.Short in the injector solenoid
Point B: Injector drive time
DThe injector drive time will be synchronized with the MUT-II
tester display.
DWhen the engine is suddenly raced, the drive time will
be greatly extended at first, but the drive time will soon
match the engine speed.
When idling
When racing ---
--
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MPI -Troubleshooting13A-121
IDLE SPEED CONTROL SERVO (STEPPER MOTOR)
Measurement Method
1. Disconnect the idle speed control servo connector, and
connect the special tool (test harness: MB991709) in
between.
2. Connect the analyzer special patterns pickup to the idle
speed control servo-side connector terminal No. 1,
terminal No. 3, terminal No. 4 and terminal No. 6
respectively.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 4, connection terminal No. 5,
connection terminal No. 17, and connection terminal No.
18 respectively.
Standard Wave Pattern
Observation conditions
FunctionSpecial patterns
Pattern heightHigh
Pattern selectorDisplay
Engine conditionWhen the engine coolant temperature is 20_C or below, turn the ignition switch from “LOCK”
(OFF) position to “ON” position (without starting the engine).
While the engine is idling, turn the A/C switch to ON.
Immediately after starting the warm engine
Standard wave pattern
Stepper
motor
control
signal
wave
pattern(V)
30
20
10The wave pattern
appears for an
instant, but soon
disappears.Point B
Coil reverse electromotive
force (Approx. 3×10 V)Point A
Induced electromotive force
from the motor turning
Time
Special
patterns
pickupAnalyzer