Toyota FJ Cruiser (GSJ 10, 15 series). Instruction - part 272

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

IN–43

•

Do not apply heat directly to the parts in
the ECU.

When a malfunction seems to occur on a rainy day
or in high-humidity.
(1) Sprinkle water onto the vehicle and check if the

malfunction occurs.
NOTICE:
•

Never sprinkle water directly into the
engine compartment. Indirectly change
the temperature and humidity by spraying
water onto the front of the radiator.

•

Never apply water directly onto the
electronic components.

HINT:
If the vehicle has or had a water leakage
problem, the leakage may have damaged the
ECU or connections. Look for evidence of
corrosion or short circuits. Proceed with caution
during water tests.

(d) HIGH ELECTRICAL LOAD METHOD:

When a malfunction seems to occur when electrical
load is excessive.
(1) Turn on the heater blower, headlight, rear

window defogger and all other electrical loads.
Check if the malfunction reoccurs.

DIAGNOSTIC TROUBLE CODE CHART

Look for output Diagnostic Trouble Codes (DTCs) (from the
DTC checks) in the appropriate section's Diagnostic Trouble
Code Chart. Use the chart to determine the trouble area and
the proper inspection procedure. A description of each of the
chart's columns are below.

PROBLEM SYMPTOMS TABLE
When a "Normal" code is output during a DTC check but
the problem is still occurring, use the Problem Symptoms
Table. The suspected areas (circuits or parts) for each
problem symptom are in the table. The suspected areas
are listed in order of probability. A description of each of
the chart's columns are below.
HINT:
In some cases, the problem is not detected by the
diagnostic system even though a problem symptom is
present. It is possible that the problem is occurring
outside the detection range of the diagnostic system, or
that the problem is occurring in a completely different
system.

D025085E02

AUTO

B107149

Item

Description

DTC No.

Indicates the diagnostic trouble code

Detection Item

Indicates the system or details of the problem

Trouble Area

Indicates the suspect areas of the problem

See Page

Indicates the page where the inspection procedures for each circuit is
to be found, or gives instruction for checking and repairs.

IN–44

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

CIRCUIT INSPECTION
A description of the main areas of each circuit inspection
is below.

Item

Description

Problem Symptom

Circuit Inspection, Inspection Order

Indicates the order in which the circuits need to be checked

Circuit or Part Name

Indicates the circuit or part which needs to be checked

See Page

Indicates the page where the flowchart for each circuit is located

Item

Description

Circuit Description

The major role, operation of the circuit and its component parts are
explained.

Diagnostic Trouble Code No. and Detection Item

Indicates the diagnostic trouble codes, diagnostic trouble code
settings and suspected areas for a problem

Wiring Diagram

This shows a wiring diagram of the circuit.
Use this diagram together with ELECTRICAL WIRING DIAGRAM to
thoroughly understand the circuit.
Wire colors are indicated by an alphabetical code:
•

B = Black

•

L = Blue

•

R = Red

•

BR = Brown

•

LG = Light Green

•

V = Violet

•

G = Green

•

O = Orange

•

W = White

•

GR = Gray

•

P = Pink

•

Y = Yellow

•

SB = Sky Blue

The first letter indicates the basic wire color and the second letter
indicates the color of the stripe.

Inspection Procedures

Use the inspection procedures to determine if the circuit is normal or
abnormal. If abnormal, use the inspection procedures to determine
whether the problem is located in the sensors, actuators, wire
harnesses or ECU.

Indicates the condition of the connector of the ECU during the check

Connector being checked is connected.
Connections of tester are indicated by (+) or (-) after the terminal
name.
Connector being checked is disconnected.
For illustrations of inspections between a connector and body ground,
information about the body ground is not shown in the illustration.

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

IN–45

ELECTRONIC CIRCUIT INSPECTION
PROCEDURE

BASIC INSPECTION
(a) WHEN MEASURING RESISTANCE OF

ELECTRONIC PARTS
(1) Unless otherwise stated, all resistance

measurements should be made at an ambient
temperature of 20

°C (68°F). Resistance

measurements may be inaccurate if measured
at high temperatures, i.e. immediately after the
vehicle has been running. Measurements should
be made after the engine has cooled down.

(b) HANDLING CONNECTORS

(1) When disconnecting a connector, first squeeze

the mating halves tightly together to release the
lock, and then press the lock claw and separate
the connector.

(2) When disconnecting a connector, do not pull on

the harnesses. Grasp the connector directly and
separate it.

(3) Before connecting a connector, check that there

are no deformed, damaged, loose or missing
terminals.

(4) When connecting a connector, press firmly until

it locks with a "click" sound.

(5) If checking a connector with a TOYOTA

electrical tester, check the connector from the
backside (harness side) using a mini test lead.
NOTICE:
•

As a waterproof connector cannot be
checked from the backside, check it by
connecting a sub-harness.

•

Do not damage the terminals by moving
the inserted tester needle.

(1) Checking when a connector is disconnected:

Squeeze the connector together to confirm that
they are fully connected and locked.

(2) Checking when a connector is disconnected:

Check by pulling the wire harness lightly from
the backside of the connector. Look for
unlatched terminals, missing terminals, loose
crimps or broken conductor wires. Check
visually for corrosion, metallic or foreign matter
and water, and bent, rusted, overheated,
contaminated, or deformed terminals.

INCORRECT

CORRECT

D032092E01

Core Wire

Terminal
Deformation

Pull Lightly

Looseness of
Crimping

D025087E03

IN–46

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

(3) Checking the contact pressure of the terminal:

Prepare a spare male terminal. Insert it into a
female terminal, and check for ample tension
when inserting and after full engagement.
NOTICE:
When testing a gold-plated female terminal,
always use a gold-plated male terminal.

(d) REPAIR METHOD OF CONNECTOR TERMINAL

(1) If there is any foreign matter on the terminal,

clean the contact point using an air gun or cloth.
Never rub the contact point using sandpaper as
the plating may come off.

(2) If there is abnormal contact pressure, replace

the female terminal. If the male terminal is gold-
plated (gold color), use a gold-plated female
terminal; if it is silver-plated (silver color), use a
silver-plated female terminal.

(3) Damaged, deformed, or corroded terminals

should be replaced. If the terminal does not lock
into the housing, the housing may have to be
replaced.

(e) HANDLING OF WIRE HARNESS

(1) If removing a wire harness, check the wiring and

clamping before proceeding so that it can be
restored in the same way.

(2) Never twist, pull or slacken the wire harness

more than necessary.

(3) The wire harness should never come into

contact with a high temperature part, or rotating,
moving, vibrating or sharp-edged parts. Avoid
contact with panel edges, screw tips and other
sharp items.

(4) When installing parts, never pinch the wire

harness.

(5) Never cut or break the cover of the wire harness.

If it is cut or broken, replace it or repair it with
vinyl tape.

CHECK FOR OPEN CIRCUIT
(a) For an open circuit in the wire harness in Fig. 1,

check the resistance or voltage, as described below.

D025088E02

CORRECT

INCORRECT

D032093E01

INCORRECT

D032094E01

Fig. 1

OPEN

ECU

SENSOR

Z017004E02

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