Isuzu N-Series. Manual - part 974

CAB AND CHASSIS ELECTRICAL 8-1

CAB AND CHASSIS ELECTRICAL

SECTION 8

CAB AND CHASSIS ELECTRICAL

Contents

GENERAL INFORMATION..................................... 8-2

General Information............................................. 8-2
Notes for Working on Electrical Items ................. 8-2
Symbols and Abbreviations ................................. 8-8
Parts for Electrical Circuit .................................. 8-11
Reading The Circuit Diagram ............................ 8-19

MAIN DATA AND SPECIFICATIONS ................... 8-22

Bulb Specifications ............................................ 8-22
Fuse and Fusible Link Location......................... 8-25
Reference Table of Fuse and Circuit Breaker ... 8-36
Relay Location................................................... 8-42
Diode Location................................................... 8-48
Reference Table of Grounding Point ................. 8-49
Grounding Point Location .................................. 8-49
Cable Harness Routing ..................................... 8-50

SYSTEM REPAIR ................................................. 8-54

Start and Charging ............................................ 8-54
QOS (Quick On Start) II System (4HF1 and 4JB1 En-
gine Model)........................................................ 8-68
Exhaust Brake System ...................................... 8-74
Exhaust Brake System and Engine Control ...... 8-84
Engine Stop System ........................................ 8-126
Headlight, Fog Light, Rear Fog Light and Cornering 
Light................................................................. 8-133
Headlight Leveling ........................................... 8-159
Clearance Light, Taillight, License Plate Light and Illu-
mination Light .................................................. 8-168
Turn Signal Light, Hazard Warning Light, and Stop-
light .................................................................. 8-183
Horn, Backup Light and Backup Buzzer.......... 8-197
Dome Light and Key Remind Buzzer .............. 8-209
Power Door Lock ............................................. 8-219
Power Window................................................. 8-231
Windshield Wiper and Washer ........................ 8-247
Audio and Cigar Lighter................................... 8-266
Meter and Warning/indicator Light................... 8-274
Heater and Air Conditioning ............................ 8-330
Fuel Heater and Rear Heater .......................... 8-342
4WD Transfer (Vacuum Control) ..................... 8-348
ABS (Anti-lock Brake System, Without ASR) .. 8-354
ABS/ASR System ............................................ 8-363
Transmission Control System (Smoother)....... 8-368
Electronic Control Type PTO........................... 8-386

8-2 CAB AND CHASSIS ELECTRICAL

GENERAL INFORMATION

General Information

The chassis electrical system is of 12-volt specifications
with a negative ground polarity.
Wire sizes are appropriate to respective circuits, and
classified by color. (The classification of harnesses by
color is shown on the circuit diagram for ease of harness
identification.)
The wire size is determined by load capacity and the
length of wire required.
The vehicle harnesses are: body harness, floor harness,
engine harness, frame front harness, frame rear har-
ness, rear body harness, dome light harness, door har-
ness and battery cable.
The harnesses are protected either by tape or corrugat-
ed tube, depending on harness location.
The circuit for each system consists of the power
source, wire, fuse, relay switch, load parts and ground,
all of which are shown on the circuit diagram.
In this manual, each electrical device is classified by
system. For major parts shown on the circuit based on
the circuit diagram for each system, a summary, diagno-
sis of troubles, inspection and removal and installation
procedures are detailed.

Notes for Working on Electrical Items

Battery Cable

Disconnecting The Battery Cable

1. All switches should be in the “OFF” position.
2. Disconnect the battery ground cable 1.
3. Disconnect the battery positive cable 2.
4. Disconnect the battery cable 3.

Caution:
It is important that the battery ground cable be discon-
nected first.
Disconnecting the battery positive cable first can result
in a short circuit.

Connecting The Battery Cable
Follow the disconnecting procedure in the reverse or-
der.

Caution:
Clean the battery terminal and apply a light coat of
grease to prevent terminal corrosion.

Connector Handling
Disconnecting The Connectors
Some connectors have a tang lock to hold the connec-
tors together during vehicle operation.
Some tang locks are released by pulling them towards
you 1.
Other tang locks are released by pressing them forward
2.
Determine which type of tang lock is on the connector
being handled.
Firmly grasp both sides (male and female) of the con-
nector.
Release the tang lock and carefully pull the two halves
of the connector apart.

N8A0001E

N8A0002E

CAB AND CHASSIS ELECTRICAL 8-3

Never pull on the wires to separate the connectors.
This will result in wire breakage.

Connecting the Connector
Firmly grasp both sides (male and female) of the con-
nector. Be sure that the connector pins and pin holes
match. Be sure that both sides of the connector are
aligned with each other. Firmly but carefully push the
two sides of the connector together until a distinct click
is heard.

Connector Inspection
Use a circuit tester to check the connector for continuity.
Insert the test probes from the connector wire side.

N8A0003E

N8A0004E

N8A0005E

N8A0006E

8-4 CAB AND CHASSIS ELECTRICAL

Never insert the circuit tester test probes into the con-
nector open end to test the continuity. Broken or open
connector terminals will result.

Waterproof Connector Inspection
It is not possible to insert the test probes into the con-
nector wire side of a waterproof connector.
Use one side of a connector 1 with its wires cut to make
the test. Connect the test connector 2 to the connector
to be tested. Connect the test probes to the cut wires to
check the connector continuity.

Connector Pin Removal
Connector Housing Tang Lock Type

1. Insert a slender shaft into the connector housing

open end.

2. Push the tang lock up (in the direction of the arrow

in the illustration). Pull the wire with pin free from
the wire side of the connector.

Pin Tang Lock Type

1. Insert a slender shaft into the connector housing

open end.

2. Push the tang lock flat (toward the wire side of the

connector). Pull the wire with pin free from the wire
side of the connector.

N8A0007E

N8A0008E

N8A0009E

N8A0010E