Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 1124

ELECTRICAL-BODY AND CHASSIS  8-253

Speedometer Off-Vehicle Inspection

Remove the speedometer from the meter assembly and
measure the resistance and the current consumption between
each terminal.
Speedometer Resistance

Tester

Terminal

terminal

symbol

Red (+)

Black (-) Black (-)

Red (+)

IGN

GND

IGN

GND

∞

30.6 - 37.4k

SEN

GND

SEN

GND

28.8 - 35.2k

∞

4P

GND

4P

GND

13.5 - 16.5k

∞

4P - GND

SEN - GND

IGN - GND

Note: Use the analog type circuit tester (range: 

× 1k).

Speedometer Current Consumption

Terminal

symbol

Current

consumption

Remarks

IGN - GND

+

-

85 

± 15mA

(when 12 

± 1V

applied)

No signal input

Note: 1. Use the analog type circuit tester.

2. Since the current consumption fluctuates when the

source voltage varies, check to be sure that the
voltage applied is 12V 

± 1V.

Tachometer On-Vehicle Inspection

1. Attach a tune-up tester to the engine.

2. Start the engine.

3. Compare the tachometer reading and the tester reading.

If  the  tachometer  indication  is  outside  the  permissible

range, the tachometer must be replaced.

4. Gradually increase and decrease the engine speed.

Note the movement of the tachometer needle.

If the needle movement is sluggish, the tachometer must be

replaced.

Gasoline engine

rpm

Indication

Permissible Range

1,000

940-1060

2,000

1875-2125

3,000

2850-3150

4,000

3820-4180

5,000

4820-5180

6,000

5820-6180

8-254  ELECTRICAL-BODY AND CHASSIS

Gasoline engine (6VD1)

Gasoline engine (6VD1)

rpm

Indication

Permissible Range

1,000

900-1060

2,000

1820-2070

3,000

2820-3120

4,000

3820-4180

5,000

4820-5180

6,000

5820-6180

7,000

6820-7180

Diesel engine

Diesel engine

rpm

Indication

Permissible Range

750

690-810

2,000

1875-2125

3,000

2850-3150

4,000

3820-4180

5,000

4820-5180

Tachometer Off-Vehicle Inspection

Remove the tachometer from the meter assembly and
measure the resistance value and the current consumption
between each terminal.

Tachometer Resistance

Tester

Terminal

terminal

symbol

Red (+)

Black (-) Black (-)

Red (+)

IGN

GND

IGN

GND

∞

23 - 31k

P

GND

P

GND

28.8 - 35.2k

∞

P - GND

IGN - GND

Note: Use the analog type circuit tester (range: 

× 1k).

Tachometer Current Consumption

Terminal

symbol

Current

consumption

Remarks

IGN - GND

+

-

90 

± 15mA

(12 

± 1V when

voltage applied)

No signal input

Note: 1. Use the analog type circuit tester.

2.

Since the current consumption fluctuates as the
source voltage varies, check to be sure that the
voltage applied is 12V 

± 1V.

ELECTRICAL-BODY AND CHASSIS  8-255

TEMPERATURE GAUGE AND THERMO

UNIT

Temperature Gauge On-Vehicle Inspection

1. Disconnect the temperature gauge wire connector.

2. Connect a 3.4 Watt test bulb 

1

 to the ground.

The  gauge  needle  should  move  the  middle  part  of  the

gauge

Temperature Gauge Off-Vehicle Inspection

Use a circuit tester to measure the temperature gauge
resistance.
Temperature Gauge Resistance

Ω

Standard

Measuring Point

With

Tachometer

Without

Tachometer

IGN (+) - Ground

130

-

IGN (+) - UNIT

82

-

UNIT - Ground

212

-

VOLTAGE

REGULATOR - UNIT

-

25

8-256  ELECTRICAL-BODY AND CHASSIS

Thermo Unit Inspection

The thermo unit is thermistor type and must be inspected
under the conditions as shown in the left chart.
1. Put  the  deviation  of  the  galvanometer  to  0  by  using  the

variable  resistor,  switch  the  thermo  unit  off  and  then

measure the resistance of the resistor through the bridge.

Confirm  that  the  resistance  is  continuously  variable  in  any

other points than those shown in the following table.

2. Dip the thermo unit into 80 - 90

°C (176 - 194°F) water and

confirm  that  there  is  no  bubble  continuously  coming  out  of

inside of the unit.

Replace  the  unit  when  the  result  of  inspection  is  found

abnormal.

Temperature

Check

condition

50

°C

(122

°F)

115

°C

(239

°F)

7V 55 

Ω

Gauge

Resistance

+33.6

226.0 

-36.6

+1.71

26.4 

-2.21

7V 25 

Ω

Gauge

value (

Ω)

-

+2.68

24.3 

-3.68