Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 1224

8-236  ELECTRICAL-BODY AND CHASSIS 

3.  Speedometer needle jumps erratically 
 

Checkpoint  

Trouble 

Cause 

 

Countermeasure 

 

Replace the vehicle speed
sensor, or repair an open
circuit in the circuit or a poor
connection at the connectors

Vehicle speed sensor
malfunction, or open circuit or
poor connector contact

NG

Replace the speedometer

Use meter tester to check the
speedometer function

Speedometer malfunction

NG

OK

Check the vehicle speed
sensor output by using the
oscilloscope

 

 
 

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 2 

B-24

 and 9

B-23

 of the meter.

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

 

 
4.  Trip odometer does not reset 
 

Replace the speedometer

Faulty reset mechanism or
worn gear

NG

Check at other kilometer
figures given by meter tester
(Reset should be made to
zero kilometer)

 

 

ELECTRICAL-BODY AND CHASSIS  8-237 

TACHOMETER 

1.  Tachometer does not function when engine is running 
 

Checkpoint  

Trouble 

Cause 

 

Countermeasure 

 

Replace the tacho sensor, or
repair open circuit or
connector contact

Tacho sensor malfunction, or
open circuit or poor connector
contact

NG

Replace the tachometer

Tachometer function

Tachometer malfunction

NG

OK

Pulse between connector

B-24

 and the ground when

engine is running (Should be
pulse present)

 

 
 
2.  Meter needle fluctuates 
 

(May be wide fluctuation) 

 

Replace the tachometer

Tachometer malfunction

NG

Use a meter tester to check
the tachometer function

 

 
 

8-238  ELECTRICAL-BODY AND CHASSIS 

TEMPERATURE GAUGE AND THERMO UNIT 

1.  No temperature indicates at all 
 

Checkpoint  

Trouble 

Cause 

 

Countermeasure 

 

Replace the thermo unit

Thermo unit malfunction

NG

Replace the temperature
gauge

Gauge function
1. Disconnect the unit

connector then connect
3.4W bulb to wire harness
side with ground

2. Check indicating point

when starter SW. is ON
position (Temperature
should indicate)

Gauge malfunction

Repair open circuit or
connector contact

Continuity between 1 

E-8

and 6 

B-24

Open circuit or poor connector
contact

NG

NG

OK

OK

Thermo unit continuity
between connector 

E-8

 and

the ground

 

 
 
2.  Temperature gauge incorrect readings in all ranges 
 

Replace the thermo unit

Thermo unit malfunction

NG

Thermo unit resistance
between connector 1 

E-8

and the ground when
disconnecting the connector
(Specified resistance should
indicate)

 

 
 

ELECTRICAL-BODY AND CHASSIS  8-239 

FUEL GAUGE AND FUEL TANK UNIT 

1.  No fuel level indicates at all 
 

Checkpoint  

Trouble 

Cause 

 

Countermeasure 

 

Replace the tank unit

Open circuit inside the tank
unit

NG

Thermo unit malfunction

Replace the fuel gauge

Fuel gauge function
1. Disconnect the tank unit

connector then connect
3.4W bulb to wire harness
side

2. Check indicating point

when starter SW. is ON
position (Fuel level should
indicate)

Gauge malfunction

Repair open circuit or
connector contact

Continuity between
connectors 11 

B-23

 and 1

F-1

Open circuit or poor connector
contact

NG

NG

OK

OK

Tank unit continuity between
connector 1 

F-1

 and ground

 

 
 
2.  Fuel gauge gives incorrect readings in all ranges 
 

Replace the tank unit

Tank unit malfunction

NG

Tank unit resistance position
with the float at checking
points (Specified resistance
should indicate)