Lexus GS300/400 (2000 year). Manual — part 158

DTC No.

Indicates the diagnostic trouble code.

Page or Instructions

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

Detection Item

Indicates the system of the problem or
contents of the problem.

Trouble Area

Indicates the suspect area of the
problem.

Mass Air Flow Circuit Malfunction

Detection Item

Open or short in mass air flow meter circuit

Mass air flow meter

ECM

DTC No.

(See page)

Trouble Area

MIL*

Memory

P0100

(DI–24)

P0101

(DI–28)

P0115

(DI–33)

Open or short in intake air temp. sensor

circuit

Intake air temp. sensor

ECM

Intake Air Temp. Circuit

Malfunction

P0110

(DI–29)

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM

Throttle/ Pedal Position Sensor/Switch

”A” Circuit Malfunction

Engine Coolant Temp.

Circuit Malfunction

Open or short in throttle position sensor circuit

Throttle position sensor

ECM

DTC CHART (SAE Controlled)

HINT:
Parameters listed in the chart may not be exactly the same as your reading due to the type of instrument or other
factors.

If a malfunction code is displayed during the DTC check mode, check the circuit for that code listed in the table
below. For details of each code, turn to the page referred to under the ”See page” for the respective ”DTC No.”
in the DTC chart.

Mass Air Flow Circuit

Range/ Performance Problem

Mass air flow meter

Throttle position sensor

Throttle/ Pedal Position Sensor/ Switch

”A” Circuit Range / Performance Prob-

lem

P0116

(DI–37)

Engine Coolant Temp.

Circuit Range/ Performance Problem

Engine coolant temp. sensor

Cooling system

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INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS

IN–27

27

4.

DIAGNOSTIC TROUBLE CODE CHART

The inspection procedure is shown in the table below. This table permits efficient and accurate troubleshoot-
ing using the diagnostic trouble codes displayed in the diagnostic trouble code check. Proceed with trouble-
shooting in accordance with the inspection procedure given in the diagnostic chart corresponding to the
diagnostic trouble codes displayed. The engine diagnostic trouble code chart is shown below as an example.

IN–28

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INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS

28

5.

PROBLEM SYMPTOMS TABLE

The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to
troubleshoot the problem when a ”Normal” code is displayed in the diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the problem symptom is present,
it is considered that the problem is occurring outside the detection range of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.

Symptom

Suspect Area

See page

Engine does not crank (Does not start)

No initial combustion (Does not start)

No complete combustion (Does not start)

1. Starter and starter relay

1. ECM power source circuit

2. Fuel pump control circuit

3. Engine control module (ECM)

1. Starter signal circuit

2. Fuel pump control circuit

1. Fuel pump control circuit

DI–147

DI–151

IN–29

PROBLEM SYMPTOMS TABLE

1. Compression

2. Fuel pump control circuit

1. A/C signal circuit

2. Fuel pump control circuit

1. A/C signal circuit (Compressor circuit)

2. ECM power source circuit

1. Starter signal circuit

2. Fuel pump control circuit

1. Starter signal circuit

2. Fuel pump control circuit

3. Compression

idling)

High engine idle speed (Poor idling)

Hot engine

Cold engine (Difficult to start)

Engine cranks normally (Difficult to start)

AC–88

DI–144

DI–151

EM–3

DI–151

Problem Symptom

Page

Indicates the page where the flow chart for each circuit
is located.

Circuit Inspection, Inspection Order

Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.

Circuit or Part Name

Indicates the circuit or part which needs to be checked.

ST–2
ST–17

DI–144

DI–151

DI–144

DI–151

V08423

Knock Sensor 1

GR

ECM

KNK

E1

12
E6

WIRING DIAGRAM

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.

DTC

P0325

Knock Sensor 1 Circuit Malfunction

CIRCUIT DESCRIPTION

Knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which

generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine

knocking occurs, ignition timing is retarded to suppress it.

DTC No.

DTC Detecting Condition

Trouble Area

P0325

No knock sensor 1 signal to ECM with engine speed,

1,200 rpm or more.

Open or short in knock sensor1 circuit

Knock sensor 1 (looseness)

ECM

If the ECM detects the above diagnosis conditions, it operates the fall safe function in which the corrective retard angle

value is set to the maximum value.

Diagnostic Trouble Code No. and Detection Item

Circuit Description

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

Indicates the diagnostic trouble code, diagnostic

trouble code set parameter and suspect area of
the problem.

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INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS

IN–29

29

6.

CIRCUIT INSPECTION

How to read and use each page is shown below.

V08425

LOCK

KNK

E6 Connector

(a) Remove the glove compartment (See page SF–68).
(b) Disconnect the E6 connector of ECM.

INSPECTION PROCEDURE

Replace knock sensor.

1

Check continuity between terminal KNK of ECM connector and body ground.

OK:

Check knock sensor (See page SF–61).

Measure resistance between terminal KNK of ECM connector
and body ground.

Resistance: 1 M

Ω

or higher

Connector being checked is connected.

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

PREPARATION:

CHECK:

2

Go to step 3.

OK

OK

NG

Indicates the position of the ignition switch during the check.

Check from the connector back side.
(with harness)

Ignition Switch LOCK (OFF)

Ignition Switch START

LOCK

Ignition Switch ON

Ignition Switch ACC

START

ON

ACC

Indicates the place to check the voltage or resistance.

Indicates the connector position to be checked, from the front or back side.

Connector being checked is disconnected.

Check from the connector front side. (without harness)
In this case, care must be taken not to bend the terminals.

E6 Connector

KNK

Wire Harness

E6 Connector

KNK

A00255

AB0117
A00265

Inspection Procedure
Use the inspection procedure to determine if
the circuit is normal or abnormal, and, if it is
abnormal, use it to determine whether the
problem is located in the sensors, actuators,
wire harness or ECU.

IN–30

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SYSTEMS

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