Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 1332

8–248 ELECTRICAL-BODY AND CHASSIS

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 permis-
sible 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.

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

Gasoline engine

rpm

821RV121

Indication

Permissible Range

750

690–810

2,000

1875–2125

3,000

2850–3150

4,000

3820–4180

5,000

4820–5180

Diesel engine

rpm

821RV118

Gasoline engine

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

Gasoline engine (6VD1)

rpm

825RW256

Gasoline engine (6VD1)

Diesel engine

ELECTRICAL-BODY AND CHASSIS 8–249

Tachometer Resistance

Note: Use the analog type circuit tester (range: x 1k).

Tester 

terminal

Red (+)

Black (–) Black (–)

Red (+)

Terminal 
symbol

IGN – GND

IGN

GND

IGN

GND

∞

23 – 31k

P

– GND

P

GND

P

GND

∞

24.7 – 33.4k

Tachometer Current Consumption

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.

Terminal Current  Remarks

symbol

consumption

90 ± 15 mA

(12 ± 1V when

No signal input

voltage applied)

IGN – GND

,

.

Tachometer Off-Vehicle Inspection

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

P

IGN

GND

821RV117

8–250 ELECTRICAL-BODY AND CHASSIS

TEMPERATURE GAUGE AND THERMO UNIT

W/O Tachometer

W/Tachometer

826RV041

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

＋

−

1

W/Tachometer

Unit

Ground

IGN 

＋

140RV006

＋

−

1

Voltage 
regulator

W/O Tachometer

Unit

140RV005

Temperature Gauge Off-Vehicle Inspection

Use a circuit tester to measure the temperature gauge
resistance.

Temperature Gauge Resistance

Ω

Standard

Measuring Point

With

Without

Tachometer

Tachometer

IGN (+) – Ground

130

–

IGN (+) – UNIT

82

–

UNIT – Ground

212

–

VOLTAGE
REGULATOR – UNIT

–

25

ELECTRICAL-BODY AND CHASSIS 8–251

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.

A

GA

Bridge

Variable resistor

Switch

Galvano
meter

55

Ω or 25Ω (Including

resistance of ammeter)

Ammeter

DC
7.0V

825RV112

FUEL GAUGE AND TANK UNIT

W/O Tachometer

W/Tachometer

826RV042

Fuel Gauge On-Vehicle Inspection

1. Disconnect the fuel gauge wire connector.

2. Connect a 3.4 Watt test bulb 1 to the ground.

The gauge needle should more the middle part of the
gauge.

＋

−

1

W/Tachometer

Unit

Ground

IGN 

＋

140RV006

Temperature

50°C

115°C

Check

(122°F)

(239°F)

condition

7V 55

Ω

226.0

+33.6

26.4

+1.71

Gauge

226.0

–36.6

26.4

–2.21

7V 25

Ω

26.4

+2.68

Gauge

—

24.3

–3.68

Resistance

value

(

Ω

)