Nissan Primera P11. Manual — part 456
Voltage check method
1. Remove the blown fuse and disconnect all loads (i.e. SW1 open, relay disconnected and solenoid dis-
connected) powered through the fuse.
2. Turn the ignition key to the ON or START position. Verify battery voltage at the B
+
side of the fuse ter-
minal (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).
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
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 corrosion (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 easily 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 screw or clip.
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
Ground Inspection
Remove bolt (screw).
Inspect mating surfaces
for tarnish, dirt, rust, etc.
Clean as required to
assure good contact.
Reinstall bolt (screw)
securely.
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-31
VOLTAGE DROP TESTS
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 strand will have a high resistance to the current.
This will be picked up as a slight voltage drop.
Unwanted resistance can be caused by many situations as follows:
Undersized wiring (single strand example)
Corrosion on switch contacts
Loose wire connections or splices.
If repairs are needed always use wire that is of the same or larger gauge.
Measuring voltage drop — Accumulated method
1. Connect the voltmeter across the connector or part of the circuit you want to check. The positive lead
of the voltmeter should be closer to power and the negative lead closer to ground.
2. Operate the circuit.
3. The voltmeter will indicate how many volts are being used to “push” current through that part of the cir-
cuit.
Note in the illustration that there is an excessive 4.1 volt drop between the battery and the bulb.
Measuring voltage drop — Step by step
The step by step method is most useful for isolating excessive drops in low voltage systems (such as those
in “Computer Controlled Systems”).
Circuits in the “Computer Controlled System” operate on very low amperage.
The (Computer Controlled) system operations can be adversely affected by any variation in resistance in
the system. Such resistance variation may be caused by poor connection, improper installation, improper
wire gauge or corrosion.
The step by step voltage drop test can identify a component or wire with too much resistance.
SGI848
Symptom: Dim bulb or no operation
0 (zero) ohm
resistance
between switch
and bulb
Ground
Battery
DMM
Power
Switch
Load
Connection with
high resistance
Ground
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-32
SGI854
1. Connect the voltmeter as shown, starting at the battery and
working your way around the circuit.
2. An unusually large voltage drop will indicate a component or
wire that needs to be repaired. The illustration shows a poor
connection causes a 4 volt drop.
The chart that follows illustrates some maximum allowable voltage drops. These values are given as a guideline, the exact value for each component
may vary.
COMPONENT
Wire
Ground Connections
Switch Contacts
VOLTAGE DROP
Negligible <.001 volts
Approx. 0.1 volts
Approx. 0.3 volts
Battery
Switch
Connection
with high
resistance
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-33
Relationship between open/short (high resistance) circuit and the ECM pin control
System Description: When the switch is ON, the ECM lights up the lamp.
SGI849-A
Case 1
Battery
FUSE
Switch
TERMINAL: 1
Monitoring
of the switch
operation (ON/OFF)
TERMINAL: 2
Power supply
to light up
the lamp
Lamp
Short:
FUSE blows.
Open:
Inoperative lamp
Short:
FUSE blows
when switch is ON.
Open:
Inoperative lamp
High resistance:
(Single strand) See below.*
ECM
Short & Open:
Inoperative lamp
Short:
No problem
Open:
Inoperative lamp
Case 2
Battery
FUSE
Lamp
TERMINAL: 1
Ground control
to light up the lamp
TERMINAL: 2
Monitoring
of the switch
operation (ON/OFF)
Switch
Short:
FUSE blows.
Open:
Inoperative lamp
Short:
Lamp stays ON.
Open:
Inoperative lamp
Short:
Lamp stays ON.
(Same as the switch ON)
Open:
Inoperative lamp
High resistance: See below.
(Single strand)*
Short:
No problem
Open:
Inoperative lamp
ECM
Pin
No.
Item
Condition
Voltage
value [V]
In case of high resistance such
as single strand [V] *
1
Switch
Switch
Battery
Lower than battery voltage
ON
voltage
Approx. 8 (Example)
OFF
Approx. 0
Approx. 0
2
Lamp
Switch
Battery
Approx. 0
ON
voltage
(Inoperative lamp)
OFF
Approx. 0
Approx. 0
The voltage value is based on the body ground.
Input-output voltage chart
Pin
No.
Item
Condition
Voltage
value [V]
In case of high resistance
such as single strand [V] *
1
Lamp
Switch
Approx. 0
Battery voltage
ON
(Inoperative lamp)
OFF
Battery
voltage
Battery voltage
2
Switch
Switch
Approx. 0
Higher than 0
ON
Approx. 4 (Example)
OFF
Approx. 5
Approx. 5
The voltage value is based on the body ground.
Input-output voltage chart
* : If high resistance exists in the switch side circuit (caused by a single strand), terminal 1 does not detect battery voltage. ECM does not detect the
switch is ON even if the switch does turn ON. Therefore, the ECM does not supply power to light up the lamp.
* : If high resistance exists in the switch side circuit (caused by a single strand), terminal 2 does not detect approx. 0V. ECM does not detect the switch
is ON even if the switch does turn ON. Therefore, the ECM does not control ground to light up the lamp.
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-34
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