Nissan Almera Tino V10. Manual — part 32
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.
SGI844
WATER INTRUSION
NLGI0005S0205
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.
SGI845
ELECTRICAL LOAD
NLGI0005S0206
The incident may be electrical load sensitive. Perform diagnoses
with all accessories (including A/C, rear window defogger, radio,
fog lamps) turned on.
COLD OR HOT START UP
NLGI0005S0207
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 diagnoses.
Circuit Inspection
NLGI0005S03
INTRODUCTION
NLGI0005S0301
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 shake the wiring harness or electrical com-
ponent 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.
I
SHORT CIRCUIT
When a circuit contacts another circuit
and causes the normal resistance to
change.
I
SHORT TO GROUND
When a circuit contacts a ground source
and grounds the circuit.
HOW TO PERFORM EFFICIENT DIAGNOSES FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests (Cont’d)
GI-24
TESTING FOR “OPENS” IN THE CIRCUIT
NLGI0005S0302
Before you begin to diagnose and test the system, you should
rough sketch a schematic of the system. This will help you to logi-
cally walk through the diagnoses process. Drawing the sketch will
also reinforce your working knowledge of the system.
SGI846
Continuity Check Method
The continuity check is used to find an open in the circuit. The
Digital Multimeter (DMM) set on the resistance 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 diagnoses 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 con-
tinuity. 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.
Voltage Check Method
To help in understanding the diagnoses 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 voltage. 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.
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HOW TO PERFORM EFFICIENT DIAGNOSES FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-25
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
NLGI0005S0303
To simplify the discussion of shorts in the system please refer to
the schematic below.
SGI847
Resistance Check Method
1)
Disconnect the battery negative cable and remove the blown
fuse.
2)
Disconnect all loads (SW1 open, relay disconnected and sole-
noid 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.
Voltage Check Method
1)
Remove the blown fuse and disconnect all loads (i.e. SW1
open, relay disconnected and solenoid disconnected) powered
through the fuse.
2)
Turn the ignition key to the ON or START position. Verify bat-
tery voltage at the B + side of the fuse terminal (one lead on
the B + terminal side of the fuse block and one lead on a known
good ground).
3)
With SW1 open and the DMM leads across both fuse
terminals, check for voltage.
voltage; short is between fuse block and SW1 (point A).
no voltage; short is further down the circuit than SW1.
4)
With SW1 closed, relay and solenoid disconnected and the
DMM leads across both fuse terminals, check for voltage.
voltage; short is between SW1 and the relay (point B).
HOW TO PERFORM EFFICIENT DIAGNOSES FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-26
no voltage; short is further down the circuit than the relay.
5)
With SW1 closed, relay contacts jumped with fused jumper
wire check for voltage.
voltage; short is down the circuit of the relay or between the
relay and the disconnected solenoid (point C).
no voltage; retrace steps and check power to fuse block.
GROUND INSPECTION
NLGI0005S0304
Ground connections are very important to the proper operation of
electrical and electronic circuits. Ground connections are often
exposed to moisture, dirt and other corrosive elements. The corro-
sion (rust) can become an unwanted resistance. This unwanted
resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper
grounding. A loose or corroded ground can drastically affect an
electronically controlled circuit. A poor or corroded ground can eas-
ily affect the circuit. Even when the ground connection looks clean,
there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:
1)
Remove the ground bolt or screw.
2)
Inspect all mating surfaces for tarnish, dirt, rust, etc.
3)
Clean as required to assure good contact.
4)
Reinstall bolt or screw securely.
5)
Inspect for “add-on” accessories which may be interfering with
the ground circuit.
6)
If several wires are crimped into one ground eyelet terminal,
check for proper crimps. Make sure all of the wires are clean,
securely fastened and providing a good ground path. If multiple
wires are cased in one eyelet make sure no ground wires have
excess wire insulation.
SGI853
VOLTAGE DROP TESTS
NLGI0005S0305
Voltage drop tests are often used to find components or circuits
which have excessive resistance. A voltage drop in a circuit is
caused by a resistance when the circuit is in operation.
Check the wire in the illustration. When measuring resistance with
ohmmeter, contact by a single strand of wire will give reading of 0
ohms. This would indicate a good circuit. When the circuit operates,
this single strand of wire is not able to carry the current. The single
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HOW TO PERFORM EFFICIENT DIAGNOSES FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-27
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