2004 INFINITI QX56 Factory Service Manual

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INFINITI QX56 2004 Factory Service Manual GI-24
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
SERVICE INFORMATION FOR ELECTRICAL INCIDENTPFP:00000
How to Check Terminal EAS0014N
CONNECTOR AND TERMINAL PIN KIT
Use

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INFINITI QX56 2004 Factory Service Manual SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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Some connectors do not have a notch above each terminal. To
probe each terminal, remove the

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INFINITI QX56 2004 Factory Service Manual GI-26
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
4. While moving the connector, check whether the male terminal
can be easily inserted or not.
If the male terminal can

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INFINITI QX56 2004 Factory Service Manual SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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How to Perform Efficient Diagnosis for an Electrical IncidentEAS0014O
WORK FLOW
INCIDENT SIMU

SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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How to Perform Efficient Diagnosis for an Electrical IncidentEAS0014O
WORK FLOW
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 fol-
lowing 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:
Vehicle vibration
Heat sensitive
SG I8 38
STEP DESCRIPTION
STEP 1Get 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/Transaxle 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 2Operate the system, road test if necessary.
Verify the parameter of the incident.
If the problem cannot be duplicated, refer to “Incident Simulation Tests”.
STEP 3Get the proper diagnosis materials together including:
Power Supply Routing
System Operation Descriptions
Applicable Service Manual Sections
Check for any Service Bulletins
Identify where to begin diagnosis based upon your knowledge of the system operation and the customer comments.
STEP 4Inspect 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 6Operate 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.

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INFINITI QX56 2004 Factory Service Manual GI-28
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
Freezing
Water intrusion
Electrical load
Cold or hot start up
Get a thorough description of the incident from the c

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SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
Freezing
Water intrusion
Electrical load
Cold 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 following illustra-
tion.
CONNECTORS & HARNESS
Determine which connectors and wiring harness would affect the electrical system you are inspecting. Gently
shake each connector and harness while monitoring the system for the incident you are trying to duplicate.
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 termi-
nals. A visual inspection may not reveal this without disconnecting the connector. If the problem occurs inter-
mittently, 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
Gently apply 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.
ENGINE COMPARTMENT
There are several reasons a vehicle or engine vibration could cause an electrical complaint. Some of the
things to check for are:
Connectors not fully seated.
Wiring harness not long enough and is being stressed due to engine vibrations or rocking.
Wires laying across brackets or moving components.
Loose, dirty or corroded ground wires.
Wires routed too close to hot components.
To inspect components under the hood, start by verifying the integrity of ground connections. (Refer to Ground
Inspection described later.) First check that the system is properly grounded. Then check for loose connection
by gently 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. Vehi-
cle vibration can aggravate a harness which is routed along a bracket or near a screw.
SG I8 39

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INFINITI QX56 2004 Factory Service Manual SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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UNDER SEATING AREAS
An unclamped or loose harness can cause wiring to be pinched by seat comp

SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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UNDER SEATING AREAS
An unclamped or loose harness can cause wiring to be pinched by seat components (such as slide guides)
during vehicle vibration. If the wiring runs under seating areas, inspect wire routing for possible damage or
pinching.
Heat Sensitive
The customer's concern 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 60°C (140°F). If incident occurs
while heating the unit, either replace or properly insulate the compo-
nent.
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 outside
overnight. In the morning, do a quick and thorough diagnosis 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 intru-
sion 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.
SGI842
SGI843
SGI844
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INFINITI QX56 2004 Factory Service Manual GI-30
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
Cold or Hot Start Up
On some occasions an electrical incident may occur only when the car is started cold, or it may o

GI-30
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
Revision: August 20072004 QX56
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.
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 thor-
ough 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 har-
ness or electrical component to do this.
NOTE:
Refer to “How to Check Terminal” to probe or check terminal.
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 work-
ing 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 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 diagnosis of open circuits, please refer to the previous schematic.
Disconnect the battery negative cable.
Start at one end of the circuit and work your way to the other end. (At the fuse block in this example)
Connect one probe of the DMM to the fuse block terminal on the load side.
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)
Connect the probes between SW1 and the relay. Little or no resistance will indicate that portion of the cir-
cuit has good continuity. If there were an open in the circuit, the DMM would indicate an over limit or infi-
nite resistance condition. (point B)
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 previous example.
OPEN A circuit is open when there is no continuity through a section of the circuit.
SHORTThere are two types of shorts.
SHORT CIRCUITWhen a circuit contacts another circuit and causes the normal resistance to
change.
SHORT TO GROUND When a circuit contacts a ground source and grounds the circuit.
SG I8 46 -A

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INFINITI QX56 2004 Factory Service Manual SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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VOLTAGE CHECK METHOD
To help in understanding the diagnosis of open circuits please refer to

SERVICE INFORMATION FOR ELECTRICAL INCIDENT
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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 voltage.
This is done by switching the DMM to the voltage function.
Connect one probe of the DMM to a known good ground.
Begin probing at one end of the circuit and work your way to the other end.
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).
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).
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 previous example.
Testing for “Shorts” in the Circuit
To simplify the discussion of shorts in the system, please refer to the following schematic.
RESISTANCE CHECK METHOD
Disconnect the battery negative cable and remove the blown fuse.
Disconnect all loads (SW1 open, relay disconnected and solenoid disconnected) powered through the
fuse.
Connect one probe of the DMM to the load side of the fuse terminal. Connect the other probe to a known
good ground.
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.
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.
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
Remove the blown fuse and disconnect all loads (i.e. SW1 open, relay disconnected and solenoid discon-
nected) powered through the fuse.
Turn the ignition key to the ON or START position. Verify battery voltage at the battery + side of the fuse
terminal (one lead on the battery + terminal side of the fuse block and one lead on a known good ground).
With SW1 open and the DMM leads across both fuse terminals, check for voltage.
voltage; short is between fuse block and SW1 (point A).
SG I8 47 -A

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