1) Using the diagnostics narrow down the causes.
2) If necessary, use a voltmeter, ohmmeter, etc.
3) Before replacing certain component parts
(switch, relay, etc.), check the power supply,
ground, for open wiring harness, poor connectors,
etc. If no problems are encountered, check the
component parts.

5. CONFIRMATION OF SYSTEM OPERA-
TION

After repairing, ensure that the system operates
properly.

B: BASIC INSPECTION

1. VOLTAGE MEASUREMENT

1) Using a voltmeter, connect the negative lead to a
good ground point or negative battery terminal and
the positive lead to the connector or component ter-
minal.
2) Contact the positive probe of the voltmeter on
connector (A).
The voltmeter will indicate a voltage.

3) Shift the positive probe to connector (B). The
voltmeter will indicate no voltage.

4) With test set-up held as it is, turn switch ON. The
voltmeter will indicate a voltage and, at the same
time, the light will come on.
5) The circuit is in good order. If a problem such as
a lamp failing to light occurs, use the procedures
outlined above to track down the malfunction.

2. CIRCUIT CONTINUITY CHECKS

1) Disconnect the battery terminal or connector so
there is no voltage between the check points.
Contact the two leads of an ohmmeter to each of
the check points.
If the circuit has diodes, reverse the two leads and
check again.
2) Use an ohmmeter to check for diode continuity.
When contacting the negative lead to the diode
positive side and the positive lead to the negative
side, there should be continuity.
When contacting the two leads in reverse, there
should be no continuity.

WI-00094

To power

FUSE

supply

Switch

Light

(A)

(B)

WI-00095

Continuity

No continuity

WI-4

WIRING SYSTEM

BASIC DIAGNOSTICS PROCEDURE

3) Symbol “

❍

—

❍

” indicates that continuity exists

between two points or terminals. For example,
when a switch position is “3”, continuity exists
among terminals 1, 3 and 6, as shown in table be-
low.

3. HOW TO DETERMINE AN OPEN CIR-
CUIT

1) Voltmeter Method:
An open circuit is determined by measuring the
voltage between respective connectors and ground
using a voltmeter, starting with the connector clos-
est to the power supply. The power supply must be
turned ON so that current flows in the circuit. If volt-
age is not present between a particular connector
and ground, the circuit between that connector and
the previous connector is open.

2) Ohmmeter method:
Disconnect all connectors affected, and check con-
tinuity in the wiring between adjacent connectors.
When the ohmmeter indicates “infinite”, the wiring
is open.

4. HOW TO DETERMINE A SHORT CIR-
CUIT

1) Test lamp method:
Connect a test lamp (rated at approximately 3
watts) in place of the blown fuse and allow current
to flow through the circuit. Disconnect one connec-
tor at a time from the circuit, starting with the one lo-
cated farthest from the power supply. If the test
lamp goes out when a connector is disconnected,
the wiring between that connection and the next
connector (farther from the power supply) is short-
ed.

2) Ohmmeter method:
Disconnect all affected connectors, and check
continuity between each connector and ground.
When ohmmeter indicates continuity between a
particular connector and ground, that connector is
shorted.

WI-00096

Terminal

Switch Position

OFF

WI-00097

Open circuit or wiring

No voltage is present

Voltage is present

WI-00098

Open circuit

Continuity does not exist.

Continuity exists.

WI-00099

Shorted wiring

Test lamp

Fuse holder

WI-00100

Shorted connector

Continuity does not exist.

Continuity exists.

WI-5

WIRING SYSTEM

BASIC DIAGNOSTICS PROCEDURE

C: HOW TO READ WIRING DIA-

GRAMS

1. WIRING DIAGRAM

The wiring diagram of each system is illustrated so that you can understand the path through which the elec-
tric current flows from the battery.
Sketches and codes are used in the diagrams. They should read as follows:
• Each connector and its terminal position are indicated by a sketch of the connector in a disconnected state
which is viewed from the front.

• The number of poles or pins, presence of a lock, and pin number of each terminal are indicated in the
sketch of each connector. In the sketch, the highest pole number refers to the number of poles which the con-
nector has. For example, the sketch of the connector shown in figure indicates the connector has 9 poles.

WI-00101

Viewed from this direction

WI-00102

Connector used in vehicle

Sketch

Symbol

Number of poles

Numbered in order from upper
right to lower left.

Numbered in order from upper
left to lower right

Connector shown in wiring diagram

Double frames

Indicates a lock
is included.

Indicates the number of poles.

Indicates a lock is included.

Single frame

Content .. 1010 1011 1012 1013 ..