Mitsubishi Space Star. Manual - part 71

MPI  – 

Troubleshooting

13B-71

CHECK AT THE ENGINE-ECU TERMINALS

TERMINAL VOLTAGE CHECK CHART

The following items have been added. The ignition timing adjustment terminal (terminal No. 52) has been
discontinued.

Terminal No.

Check item

Check condition

Normal condition

10

Ignition coil – No. 1,
No. 4 (Ignition power
transistor)

Engine r/min: 3,000 r/min

0.3 – 3.0 V

23

Ignition coil – No. 2,
No. 3 (Ignition power
transistor)

Engine r/min: 3,000 r/min

0.3 – 3.0 V

58

Engine ignition signal

Engine r/min: 3,000 r/min

0.3 – 3.0 V

88

Camshaft position 
sensor

Engine: Cranking

0.4 – 3.0 V

sensor

Engine: Idling

0.5 – 2.0 V

CHECK CHART FOR RESISTANCE AND CONTINUITY BETWEEN TERMINALS

Terminal No.

Check item

Normal condition (check condition)

54 – 12

Oxygen sensor heater (rear)

4.5 – 8.0 

Ω

 (at 20



C)

60 – 12

Oxygen sensor heater (front)

11 – 18 

Ω

 (at 20



C)

MPI  – 

Troubleshooting

13B-72

INSPECTION PROCEDURE USING AN
ANALYZER

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 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 2.

Alternate Method (Test harness not available)

1.

Connect the analyzer special patterns pickup to
engine-ECU terminal 88. (When checking the camshaft
position sensor signal wave pattern.)

2.

Connect the analyzer special patterns pickup to
engine-ECU terminal 89. (When checking the crank angle
sensor signal wave pattern.)

Standard Wave Pattern

Observation conditions

Function

Special patterns

Pattern height

Low

Pattern selector

Display

Engine r/min

Idle speed

Crank angle 
sensor connector

Camshaft position sen-
sor connector

Analyzer

Special patterns
pick-up

MPI  – 

Troubleshooting

13B-73

Standard wave pattern

Crank angle 
sensor output
wave pattern

(V)

75



BTDC

2 engine revolutions 
(1 camshaft revolution)

5



BTDC

The time (cycle time) T is
reduced when the engine
speed increases

0

Camshaft posi-
tion sensor out-
put wave pat-
tern

TDC: Top dead centre

130

°

50

°

No. 1
TDC

No. 3 TDC

No. 4
TDC

No. 2
TDC

Time

0

145

°

35

°

Wave Pattern Observation Points

Check that cycle time T becomes shorter when the engine speed increases.

Examples of Abnormal Wave Patterns



Example 1

Cause of problem

Sensor interface malfunction

Wave pattern characteristics

Rectangular wave pattern is output even when the engine
is not started.



Example 2

Cause of problem

Loose timing belt
Abnormality in sensor disk

Wave pattern characteristics

Wave pattern is displaced to the left or right.

MPI  – 

Troubleshooting

13B-74

IDLE SPEED CONTROL (ISC) SERVO (STEPPER
MOTOR)

Measurement Method

1.

Disconnect the ISC servo connector, and connect the
special tool (test harness: MB991709) in between. (All
terminals should be connected.)

2.

Connect the analyzer special patterns pickup to the ISC
servo-side connector terminal 1, terminal 3, terminal 4
and terminal 6 respectively.

Alternate Method (Test harness not available)

1.

Connect the analyzer special patterns pickup to
engine-ECU terminal 4, connection terminal 5, connection
terminal 17, and connection terminal 18 respectively.

Standard Wave Pattern

Observation conditions

Function

Special patterns

Pattern height

High

Pattern selector

Display

Engine condition

When the engine coolant temperature is 20



C or below, turn the ignition switch

from OFF to ON (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

The wave pattern 
appears for an 
instant, but soon 
disappears.

Point B
Coil reverse 
electromotive force
(Approx. 3 

×

 10 V)

Point A
Induced electro-
motive force from
the motor turning

(V)

30

20

10

ISC
servo
control
signal
pat-
tern

Time

Special patterns pickup

Analyzer