NISSAN PICK-UP 1998 Repair Manual

FOLDOUT PAGE
The foldout page should be opened when reading wiring diagram.
Super multiple junction (SMJ)
In wiring diagram, connectors consisting of terminals having terminal numbers with an alphabet (1B, 0D, etc.)
are SMJ connectors.
If connector numbers are shown in Reference Area, these connector symbols are not shown in Connector
Area. For terminal arrangement of these connectors, refer to the foldout page at the end of this manual.
Joint connector
Joint connector symbols are shown in Connector Area in the wiring diagram concerned. Foldout page also
carries inside wiring layout together with such joint connector symbols.
SGI943
HOW TO READ WIRING DIAGRAMS
Description (Cont'd)
GI-17

How to Probe Connectors
Connector damage and an intermittent connection can result
from improperly probing of the connector during circuit checks.
The probe of a digital multimeter (DMM) may not correctly fit the
connector cavity. To correctly probe the connector, follow the
procedures below using a ``T'' pin. For the best contact grasp the
``T'' pin using an alligator clip.
PROBING FROM HARNESS SIDE
Standard type (not waterproof type) connector should be probed
from harness side with ``T'' pin.
lIf the connector has a rear cover such as a ECM
connector, remove the rear cover before probing the ter-
minal.
lDo not probe waterproof connector from harness side.
Damage to the seal between wire and connector may
result.
PROBING FROM TERMINAL SIDE
Female terminal
lThere is a small notch above each female terminal. Probe
each terminal with the ``T'' pin through the notch.
Do not insert any object other than the same type male ter-
minal into female terminal.
lSome connectors do not have a notch above each terminal.
To probe each terminal, remove the connector retainer to
make contact space for probing.
Male terminal
Carefully probe the contact surface of each terminal using a ``T''
pin.
Do not bend terminal.
SGI841
SEL265V
SEL266V
SEL267V
HOW TO CHECK TERMINAL
GI-18

How to Check Enlarged Contact Spring of
Terminal
An enlarged contact spring of a terminal may create intermittent
signals in the circuit.
If the intermittent open circuit occurs, follow the procedure below
to inspect for open wires and enlarged contact spring of female
terminal.
1. Assemble a male terminal and approx. 10 cm (3.9 in) of wire.
Use a male terminal which matches the female terminal.
2. Disconnect the suspected faulty connector and hold it termi-
nal side up.
3. While holding the wire of the male terminal, try to insert the
male terminal into the female terminal.
Do not force the male terminal into the female terminal with
your hands.
4. While moving the connector, check whether the male termi-
nal can be easily inserted or not.
lIf the male terminal can be easily inserted into the female
terminal, replace the female terminal.
SEL270V
SEL271V
SEL272V
SEL273V
HOW TO CHECK TERMINAL
GI-19

Waterproof Connector Inspection
If water enters the connector, it can short interior circuits. This
may lead to intermittent problems.
Check the following items to maintain the original waterproof
characteristics.
RUBBER SEAL INSPECTION
lMost waterproof connectors are provided with a rubber seal
between the male and female connectors. If the seal is
missing, the waterproof performance may not meet specifi-
cations.
lThe rubber seal may come off when connectors are discon-
nected. Whenever connectors are reconnected, make sure
the rubber seal is properly installed on either side of male or
female connector.
WIRE SEAL INSPECTION
The wire seal must be installed on the wire insertion area of a
waterproof connector. Be sure that the seal is installed properly.
Terminal Lock Inspection
Check for unlocked terminals by pulling wire at the end of con-
nector. An unlocked terminal may create intermittent signals in
the circuit.
SEL275V
SEL330V
HOW TO CHECK TERMINAL
GI-20

Work Flow
STEP DESCRIPTION
STEP 1 Get detailed information about the conditions and the environment when the incident occurred.
The following are key pieces of information required to make a good analysis:
WHATVehicle Model, Engine, Transmission and the System (i.e. Radio).
WHENDate, Time of Day, Weather Conditions, Frequency.
WHERERoad Conditions, Altitude and Traffic Situation.
HOWSystem Symptoms, Operating Conditions (Other Components Interaction).
Service History and if any After Market Accessories have been installed.
STEP 2 Operate the system, road test if necessary.
Verify the parameter of the incident.
If the problem can not be duplicated, refer to ``Incident Simulation Tests'' next page.
STEP 3 Get the proper diagnosis materials together including:
POWER SUPPLY ROUTING
System Operation Descriptions
Applicable Service Manual Sections
Check for any Service Bulletin.
Identify where to begin diagnosis based upon your knowledge of the system operation and the customer comments.
STEP 4 Inspect the system for mechanical binding, loose connectors or wiring damage.
Determine which circuits and components are involved and diagnose using the Power Supply Routing and Harness
Layouts.
STEP 5 Repair or replace the incident circuit or component.
STEP 6 Operate the system in all modes. Verify the system works properly under all conditions. Make sure you have not inad-
vertently created a new incident during your diagnosis or repair steps.
SGI838
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
GI-21

Incident Simulation Tests
INTRODUCTION
Sometimes the symptom is not present when the vehicle is brought in for service. If possible, re-create the
conditions present at the time of the incident. Doing so may help avoid a No Trouble Found Diagnosis. The
following section illustrates ways to simulate the conditions/environment under which the owner experiences
an electrical incident.
The section is broken into the six following topics:
lVehicle vibration
lHeat sensitive
lFreezing
lWater intrusion
lElectrical load
lCold or hot start up
Get a thorough description of the incident from the customer. It is important for simulating the conditions of
the problem.
VEHICLE VIBRATION
The problem may occur or become worse while driving on a rough road or when engine is vibrating (idle
with A/C on). In such a case, you will want to check for a vibration related condition. Refer to the illustra-
tion below.
Connectors & harness
Determine which connectors and wiring harness would affect the electrical system you are inspecting.Gen-
tlyshake each connector and harness while monitoring the system for the incident you are trying to dupli-
cate. This test may indicate a loose or poor electrical connection.
Hint
Connectors can be exposed to moisture. It is possible to get a thin film of corrosion on the connector ter-
minals. A visual inspection may not reveal this without disconnecting the connector. If the problem occurs
intermittently, perhaps the problem is caused by corrosion. It is a good idea to disconnect, inspect and clean
the terminals on related connectors in the system.
Sensors & relays
Gentlyapply a slight vibration to sensors and relays in the system you are inspecting.
This test may indicate a loose or poorly mounted sensor or relay.
SGI839
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
GI-22

Engine compartment
There are several reasons a vehicle or engine vibration could
cause an electrical complaint. Some of the things to check for
are:
lConnectors not fully seated.
lWiring harness not long enough and is being stressed due
to engine vibrations or rocking.
lWires laying across brackets or moving components.
lLoose, dirty or corroded ground wires.
lWires routed too close to hot components.
To inspect components under the hood, start by verifying the
integrity of ground connections. (Refer to GROUND INSPEC-
TION described later.) First check that the system is properly
grounded. Then check for loose connection bygently shaking
the wiring or components as previously explained. Using the
wiring diagrams inspect the wiring for continuity.
Behind the instrument panel
An improperly routed or improperly clamped harness can
become pinched during accessory installation. Vehicle vibration
can aggravate a harness which is routed along a bracket or near
a screw.
Under seating areas
An unclamped or loose harness can cause wiring to be pinched
by seat components (such as slide guides) during vehicle vibra-
tion. If the wiring runs under seating areas, inspect wire routing
for possible damage or pinching.
HEAT SENSITIVE
The owner's problem may occur during hot weather or after car
has sat for a short time. In such cases you will want to check for
a heat sensitive condition.
To determine if an electrical component is heat sensitive, heat
the component with a heat gun or equivalent.
Do not heat components above 60ÉC (140ÉF).If incident
occurs while heating the unit, either replace or properly insulate
the component.
SGI842
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests (Cont'd)
GI-23

FREEZING
The customer may indicate the incident goes away after the car
warms up (winter time). The cause could be related to water
freezing somewhere in the wiring/electrical system.
There are two methods to check for this. The first is to arrange
for the owner to leave his car overnight. Make sure it will get cold
enough to demonstrate his complaint. Leave the car parked out-
side overnight. In the morning, do a quick and thorough diagno-
sis of those electrical components which could be affected.
The second method is to put the suspect component into a
freezer long enough for any water to freeze. Reinstall the part
into the car and check for the reoccurrence of the incident. If it
occurs, repair or replace the component.
WATER INTRUSION
The incident may occur only during high humidity or in rainy/
snowy weather. In such cases the incident could be caused by
water intrusion on an electrical part. This can be simulated by
soaking the car or running it through a car wash.
Do not spray water directly on any electrical components.
ELECTRICAL LOAD
The incident may be electrical load sensitive. Perform diagnosis
with all accessories (including A/C, rear window defogger, radio,
fog lamps) turned on.
COLD OR HOT START UP
On some occasions an electrical incident may occur only when
the car is started cold. Or it may occur when the car is restarted
hot shortly after being turned off. In these cases you may have
to keep the car overnight to make a proper diagnosis.
SGI843
SGI844
SGI845
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests (Cont'd)
GI-24

Circuit Inspection
INTRODUCTION
In general, testing electrical circuits is an easy task if it is approached in a logical and organized method.
Before beginning it is important to have all available information on the system to be tested. Also, get a
thorough understanding of system operation. Then you will be able to use the appropriate equipment and
follow the correct test procedure.
You may have to simulate vehicle vibrations while testing electrical components.Gently shakethe wiring
harness or electrical component to do this.
OPEN A circuit is open when there is no continuity through a section of the circuit.
SHORT There are two types of shorts.
lSHORT CIRCUITWhen a circuit contacts another circuit and causes the
normal resistance to change.
lSHORT TO GROUNDWhen a circuit contacts a ground source and grounds the
circuit.
TESTING FOR ``OPENS'' IN THE CIRCUIT
Before you begin to diagnose and test the system, you should rough sketch a schematic of the system. This
will help you to logically walk through the diagnosis process. Drawing the sketch will also reinforce your
working knowledge of the system.
Continuity check method
The continuity check is used to find an open in the circuit. The Digital Multimeter (DMM) set on the resis-
tance function will indicate an open circuit as over limit (no beep tone or no ohms symbol). Make sure to
always start with the DMM at the highest resistance level.
To help in understanding the diagnosis of open circuits please refer to the schematic above.
1. Disconnect the battery negative cable.
2. Start at one end of the circuit and work your way to the other end. (At the fuse block in this example)
3. Connect one probe of the DMM to the fuse block terminal on the load side.
4. Connect the other probe to the fuse block (power) side of SW1. Little or no resistance will indicate that
portion of the circuit has good continuity. If there were an open in the circuit, the DMM would indicate
an over limit or infinite resistance condition. (point A)
5. Connect the probes between SW1 and the relay. Little or no resistance will indicate that portion of the
circuit has good continuity. If there were an open in the circuit, the DMM would indicate an over limit or
infinite resistance condition. (point B)
6. Connect the probes between the relay and the solenoid. Little or no resistance will indicate that portion
of the circuit has good continuity. If there were an open in the circuit, the DMM would indicate an over
limit or infinite resistance condition. (point C)
Any circuit can be diagnosed using the approach in the above example.
SGI846
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
GI-25

Voltage check method
To help in understanding the diagnosis of open circuits please refer to the previous schematic.
In any powered circuit, an open can be found by methodically checking the system for the presence of volt-
age. This is done by switching the DMM to the voltage function.
1. Connect one probe of the DMM to a known good ground.
2. Begin probing at one end of the circuit and work your way to the other end.
3. With SW1 open, probe at SW1 to check for voltage.
voltage; open is further down the circuit than SW1.
no voltage; open is between fuse block and SW1 (point A).
4. Close SW1 and probe at relay.
voltage; open is further down the circuit than the relay.
no voltage; open is between SW1 and relay (point B).
5. Close the relay and probe at the solenoid.
voltage; open is further down the circuit than the solenoid.
no voltage; open is between relay and solenoid (point C).
Any powered circuit can be diagnosed using the approach in the above example.
TESTING FOR ``SHORTS'' IN THE CIRCUIT
To simplify the discussion of shorts in the system please refer to the schematic below.
Resistance check method
1. Disconnect the battery negative cable and remove the blown fuse.
2. Disconnect all loads (SW1 open, relay disconnected and solenoid disconnected) powered through the
fuse.
3. Connect one probe of the ohmmeter to the load side of the fuse terminal. Connect the other probe to a
known good ground.
4. With SW1 open, check for continuity.
continuity; short is between fuse terminal and SW1 (point A).
no continuity; short is further down the circuit than SW1.
5. Close SW1 and disconnect the relay. Put probes at the load side of fuse terminal and a known good
ground. Then, check for continuity.
continuity; short is between SW1 and the relay (point B).
no continuity; short is further down the circuit than the relay.
6. Close SW1 and jump the relay contacts with jumper wire. Put probes at the load side of fuse terminal
and a known good ground. Then, check for continuity.
continuity; short is between relay and solenoid (point C).
no continuity; check solenoid, retrace steps.
SGI847
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont'd)
GI-26