Isuzu N-Series. Manual — part 1009

CAB AND CHASSIS ELECTRICAL 8-141

Diagnosis

Quick Chart for Check Point
1. Headlight

Notice:
Figure in parenthesis “( )” indicates the order of inspection.

Check point

Fuse

Fus-

ible
link

Head-

light

relay

Light-

ing

SW

Dim-

mer /

Pass-

ing

SW

Dim-

mer

relay

Headlight

bulb

Cable

har-

ness

F-6
F-8

(10 A)

F-23

(10 A)

F-24

(10 A)

FL-4

(30A)

LH

RH

Trouble
mode

1-1. Both Head-
lights inopera-
tive

❍

(2)

❍

(1)

❍

(4)

❍

(3)

1-2. Headlight
on the left (or
right) side inop-
erative

❍

(1)

❍

((1))

❍

(2)

1-3. Headlight in
low-beam inop-
erative

❍

(1)

❍

(2)

1-4. Headlight in
high-beam inop-
erative

❍

(1)

❍

(2)

1-5. Headlight
on the left (or
right) side in low
(or high)-beam
inoperative

❍

(1)

❍

((1))

❍

(2)

1-6. Headlight
beam does not
change

❍

(1)

❍

(2)

❍

(3)

❍

(4)

1-7. Headlights
remain on when
the lighting
switch turned off

❍

(1)

❍

(2)

❍

(3)

1-8. Headlights
come on with
the lighting SW
at the clearance
light position

❍

(1)

8-142 CAB AND CHASSIS ELECTRICAL

2. Fog Light

Notice:
Figure in parenthesis “( )” indicates the order of inspection.

3. Cornering Light

4. Rear Fog Light

Check point

Fuse

F-6 (10 A): 4JH1,4JB1, 4JB1-

TC

F-8 (10 A): 24V, 4HG1-T (12 V)

Tail-
light

relay

Fog

light

SW

Fog light

bulb

Cable

harness

LH

RH

Trouble
mode

2-1. Both fog lights inopera-
tive (while lighting switch is
on)

❍

(1)

❍

(2)

❍

(3)

❍

(4)

2-2. Fog light on the left (or
right) side inoperative (while
lighting switch is on)

❍

(1)

❍

((1))

❍

(2)

2-3. Fog lights remain on

❍

(1)

❍

(2)

❍

(3)

Check point

Fuse

Cornering

light SW

Cornering

light bulb

Cornering

light relay

Cable

harness

F-6 : 4JH1,4JB1,4JB1-

TC

F-8 : 24V,4HG1-T(12V)

F-16

(10 A)

Trouble
mode

3-1. Both corner-
ing lights inoper-
ative

❍

(2)

❍

(1)

❍

(5)

❍

(3)

❍

(4)

3-2. Cornering
light on the left
(or right) side
inoperative

❍

(2)

❍

(1)

❍

(3)

3-3. Cornering
light remains on
even when steer-
ing wheel is in
the straight
ahead position

❍

(1)

Check point

Fuse

F-27 (15 A)

Rear fog

light SW

Rear fog

light relay

Rear fog

light bulb

Cable

harness

Trouble
mode

4-1. Rear fog light inoperative
(while headlight is ON)

❍

(2)

❍

(4)

❍

(3)

❍

(1)

❍

(5)

CAB AND CHASSIS ELECTRICAL 8-143

1. Headlight
1-1. Both Headlights Inoperative

1-2. Headlight on The Left (or Right) Side Inoperative

N8A0118E

IS FUSE F-24 OR F-23 (10A) NORMAL?

YES

NO

REPLACE THE FUSE

REPAIR A POOR CONNECTION AT THE CONNECTORS
OR AN OPEN CIRCUIT BETWEEN FUSE F-24 (10A) AND
3 B-4 (OR 3 B-148 ) OR FUSE F-23 (10A) AND 3 B-73
(OR 3 B-150 )

•

N8A0119E

8-144 CAB AND CHASSIS ELECTRICAL

1-3. Headlight in Low-beam Inoperative

1-4. Headlight in High-beam Inoperative

N8A0120E

• IS THE DIMMER RELAY NORMAL?

• DISCONNECT THE DIMMER / PASSING SW

CONNECTOR

• IS THERE ANY CONTINUITY BETWEEN SW SIDE

CONNECTORS 4 B-70 AND 10 B-70 WHEN THE SW IS
AT HIGH-BEAM POSITION?

YES

NO

REPLACE THE RELAY

REPAIR A POOR CONNECTION AT THE CONNECTORS
OR AN OPEN CIRCUIT BETWEEN 1 X-6 AND 2 B-74

YES

NO

REPAIR OR REPLACE THE SW

• DISCONNECT THE HEADLIGHT RELAY

• IS THERE ANY CONTINUITY BETWEEN CHASSIS SIDE

CONNECTORS 10 B-70 AND 5 X-3 ?

YES

NO

REPAIR A POOR CONNECTION AT THE
CONNECTORS OR AN OPEN CIRCUIT
BETWEEN 10 B-70 AND 5 X-3

IS FUSE F-6 OR F-8 CONNECTED?

YES

NO

REPLACE THE FUSE

•

N8A0121E