Isuzu Trooper (1998-2002 year). Manual - part 979

 

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Isuzu Trooper (1998-2002 year). Manual - part 979

 

 

8D–450

WIRING SYSTEM

1-4.  Speedometer Needle Fluctuations (May Be Wide Fluctuation)

•

DOES THE VEHICLE SPEED SENSOR OUTPUT
NORMALLY?

YES

THE OSCILLOSCOPE WAVEFORM IS DEFORMED

REPLACE THE METER ASSEMBLY

REPLACE THE VEHICLE SPEED SENSOR OR REPAIR
A POOR CONNECTION AT THE CONNECTORS IN THE
CIRCUIT OR A FAILURE IN THE CABLE HARNESS

NO

1-5.  Speedometer Needle Jumps Erratically

•

DOES THE VEHICLE SPEED SENSOR OUTPUT
NORMALLY?

YES

AN ABNORMAL PERIODIC WAVEFORM IS OUTPUT BY
OSCILLOSCOPE

REPLACE THE METER ASSEMBLY

REPLACE THE VEHICLE SPEED SENSOR, OR REPAIR
A POOR CONNECTION AT THE CONNECTORS IN THE
CIRCUIT OR A FAILURE IN THE CABLE HARNESS

NO

WIRING SYSTEM

8D–451

I-9

I-10

Inspection of a waveform by oscilloscope

1. Connect a resistance of 1.3 to 5k ohm (1.4W or more) between the harness side connectors 15   I-9

and 5   I-10   (w/o TOD) or 26   I-9   and 5   I-10

2.
3.
4.

Install a speedometer tester.
Turn on the starter SW.
Check the waveform at the time when the car speed is at 60 km/h.

Normal waveform

OV

23.6m sec.

2V or less

Approximate battery voltage

1

2

3

4

5

6

7

8

9 10 11 12 13 14

15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30

1 2 3 4

13 14

5

6 7 8 9 10

15 16

17 18 19 20

11 12

21 22

2.  Tachometer

2-1.  Tachometer Does Not Function

•

IS THE PULSE INPUT NORMAL?

YES

REPLACE THE PCM, ECM OR REPAIR A POOR
CONNECTION AT THE CONNECTORS IN THE CIRCUIT
OR A FAILURE IN THE CABLE HARNESS

NO

REPLACE THE METER ASSEMBLY

8D–452

WIRING SYSTEM

2-2.  Tachometer Needle Fluctuates (May Be Wide Fluctuation)

•

IS THE PULSE INPUT NORMAL?

YES

THE WAVEFORM BY OSCILLOSCOPE IS DEFORMED
(ABNORMAL INPUT)

NO

REPLACE THE METER ASSEMBLY

REPLACE THE PCM, ECM OR REPAIR A POOR
CONNECTION AT THE CONNECTORS IN THE CIRCUIT
OR A FAILURE IN THE CABLE HARNESS

2-3.  Tachometer Needle Jumps Erratically

•

IS THE PULSE INPUT NORMAL?

YES

AN ABNORMAL PERIODIC WAVEFORM IS OUTPUT
BY OSCILLOSCOPE

NO

REPLACE THE METER ASSEMBLY

REPLACE THE PCM, ECM OR REPAIR A POOR
CONNECTION AT THE CONNECTORS IN THE CIRCUIT
OR A FAILURE IN THE HARNESS

WIRING SYSTEM

8D–453

I-9

Inspection of a waveform by oscilloscope

1. Check the waveform of the meter assembly connector 9    I-9    (Tachometer pulse).

Normal waveform

OV

6.7m sec.

MIN. 0.4V

MAX. 4.3V

Engine revolution :  3000 rpm

1

2

3

4

5

6

7

8

9 10 11 12 13 14

15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30

 

 

 

 

 

 

 

Content   ..  977  978  979  980   ..