Isuzu N-Series. Manual - part 637

ENGINE ELECTRICAL 6D-41

QOS III Flow Chart

N6A3722E

6D-42 ENGINE ELECTRICAL

QOS II Timing Chart

Inspection on QOSIII System Operation

Inspection on Quick Heating Operation

1. Disconnect thermo-sensor connection on the ther-

mostat housing.

2. Connect the circuit tester between glow plug and

engine earth.

3. Inspect the following items with starter switch set to

ON position (but do not start the engine).
1) The glow indicator shall light for 1 — 6 seconds.

2) The circuit tester shall indicate power supply

voltage for 9 — 13 seconds.

• If above specifications are not satisfied, inspect

wire harness, glow relay and thermo-sensor. If
satisfied, inspect glow plug.

N6A3723E

N6A3039E

N6A3725E

ENGINE ELECTRICAL 6D-43

Inspection on Quick Heating Afterglow Operation

1. Disconnect thermo-sensor connection on the ther-

mostat housing.

2. Connect the circuit tester between glow plug and

engine earth.

3. Inspect the following item with start the engine.

1) The circuit tester shall indicate power supply

voltage for about 5 seconds.

• If above specification is not satisfied, inspect

battery voltage, engine earth, wire harness and
starter switch “st” signal to control unit.
If satisfied, inspect wiring harness, engine
earth and starter switch.

Inspection on Afterglow Operation

1. Disconnect thermo-sensor connection on the ther-

mostat housing.

2. Connect the circuit tester between glow plug and

engine earth.

3. Inspect the following items with start the engine.

1) The circuit tester shall indicate about 7 volts af-

ter 360 seconds of engine start.

• If above specifications are not satisfied, inspect

battery voltage, engine earth, wiring harness,
glow plug, dropping resistor, relay No. 2 and
charge relay.

N6A3039E

N6A3725E

N6A3039E

N6A3725E

6D-44 ENGINE ELECTRICAL

Thermo Sensor

Measure the resistance depending on the water temper-
ature as shown in the left figure. (Measuring range: 10

°C

— 50

°C)

When installing the thermo sensor, apply sealant (Loc-
tite #262 or equivalent) (1) to narrowed portion in figure
to prevent water leakage.

Tighten:
Thermo sensor to 8 N

⋅m (0.8 kg⋅m/69 lb⋅in)

Glow Plug

Inspect the resistance

Tighten:
Glow plug to 23 N

⋅m (2.3 kg⋅m/17 lb⋅ft)

Dropping Resistor

Inspect the resistance

Glow Plug Relay

Inspect the continuity

If apply the battery voltage to terminal between 4 — 5

Temperature

Current (mA)

Resistance (KW)

20 

± 1

1.0

2.0 — 3.0

50 

± 1

1.0

0.68 — 1.0

Resistance at normal temperature

Ω

0.8 — 1.0

N6A3730E

N6A3731E

Resistance of normal ambient temperature

m

Ω

225 — 255

2 — 3

No Continuity

2 — 3

Continuity

N6A3732E

N6A3733E