TOYOTA T100 1996 Factory Owner's Manual

Downloaded from www.Manualslib.com manuals search engine DIAGNOSTIC TROUBLE CODE CHECK PROCEDURE
Diagnostic Trouble
Code Check (Make a
note of and then clear)Confirmation
of SymptomsDiagnostic Trouble
Code CheckProblem Condition
Diagnostic Trouble
Code DisplayProblem symptoms
existSame diagnostic
trouble code is
displayedProblem is still occurring in the diagnostic
circuit.
Normal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit.
(The diagnostic trouble code displayed
first is either for a past problem or it is a
secondary problem.)
No problem
symptoms existThe problem occurred in the diagnostic
circuit in the past.
Normal Code DisplayProblem symptoms
existNormal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit.
No problem
symptoms existNormal code is
displayedThe problem occurred in a place other
than in the diagnostic circuit in the past.
IN−18− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
2. SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the TOYOTA T100 fulfills various functions. The first function is the Diagnostic
Trouble Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU
memory at the time of occurrence, to be output by the technician during troubleshooting. Another function
is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can
be performed effectively. Diagnostic functions are incorporated in the following systems in the TOYOTA
T100.
SystemDiagnostic Trouble
Code CheckInput Signal Check
(Sensor Check)Other Diagnosis
Function
Engine (3RZ−FE, 5VZ−FE)
Automatic Transmission
Anti−Lock Brake system
Supplemental Restraint System
Cruise Control (with Test Mode)
 (with Test Mode)






Cancel Signal
Check
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diag-
nostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition,
it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic
trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes
should be checked before and after the symptom confirmation to determine the current conditions, as shown
in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting
for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent
to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble
code check.

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Making a note of and clearing of the diagnostic trouble codes displayed
Symptom confirmation
No problem symptoms
exist Problem symptoms
exist
Simulation test using the symptom
simulation methods
 Normal code displayed
 Problem symptoms exist Normal code displayed
 No problem symptoms exist Diagnostic trouble code check
Troubleshooting of problem indicated
by diagnostic trouble code Diagnostic trouble code displayed
 Problem symptoms exist
System Normal Troubleshooting of each
problem symptom
If a diagnostic trouble code was
displayed in the initial diagnostic
trouble code check, it indicates
that the trouble may have occurred
in a wire harness or connector in
that circuit in the past. Therefore,
check the wire harness and con-
nectors (See page IN−26).
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−19
1996 TOYOTA T100 (RM449U)
Taking into account the points on the previous page, a flow chart showing how to proceed with troubleshoot-
ing using the diagnostic trouble code check is shown below. This flow chart shows how to utilize the diagnos-
tic trouble code check effectively, then by carefully checking the results, indicates how to proceed either to
diagnostic trouble code troubleshooting or to troubleshooting of problem symptoms.

Downloaded from www.Manualslib.com manuals search engine V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check if the
malfunction occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT: Applying strong vibration to relays may result in open
relays. IN−20
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer’s vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot condition or the
vehicle at a standstill. Since vibration, heat or water penetration (moisture) is likely cause for problem which
is difficult to reproduce, the symptom simulation tests introduced here are effective measures in that the ex-
ternal causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the matrix chart of problem symptoms for each system to narrow down the
possible causes of the symptom.

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HEAT METHOD: When the problem seems to occur when the suspect area is heated. 2
NOTICE:
(1) Do not heat to more than 60 °C (140 °F). (Temperature
is limited not to damage the components.)
(2) Do not apply heat directly to parts in the ECU.
3 WATER SPRINKLING METHOD:
NOTICE:
(1) Never sprinkle water directly into the engine
compartment, but indirectly change the temperature and
humidity by applying water spray onto the radiator front
surface.
(2) Never apply water directly onto the electronic
components.
4 OTHER: When a malfunction seems to occur when electrical load is excessive.When the malfunction seems to occur on a rainy day or in a
high−humidity condition. Heat the component that is the likely cause of the malfunction
with a hair dryer or similar object. Check to see if the malfunction
occurs.
Sprinkle water onto the vehicle and check to see if the malfunc-
tion occurs.
Turn on all electrical loads including the heater blower, head
lights, rear window defogger, etc. and check to see if the mal-
function occurs.ON (Service hint)
If a vehicle is subject to water leakage, the leaked water may
contaminate the ECU. When testing a vehicle with a water leak-
age problem, special caution must be taken.
Malfunc-
tion
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−21
1996 TOYOTA T100 (RM449U)

Downloaded from www.Manualslib.com manuals search engine  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 MalfunctionDetection Item
 Open or short in mass air flow meter circuit
 Mass air flow meter
 ECM DTC No.
(See page)Trouble AreaMIL*MemoryP0100
(DI − 26)
P0101
(DI − 31)Mass Air Flow Circuit
Range/Performance Problem Mass air flow meter
P0115
(DI − 37) Open or short in intake air temp. sensor circuit
 Intake air temp. sensor
 ECM Intake Air Temp. Circuit Malfunction P0110
(DI − 32)
Engine Coolant Temp. Circuit
Range/Performance Problem Open or short in engine coolant temp. sensor circuit
 Engine coolant temp. sensor
 ECM
P0120
(DI − 43)
Throttle/ Pedal Position Sensor/Switch
”A” Circuit Range/Performance
P0116
(DI − 41)
Throttle/Pedal Position Sensor/Switch
”A” Circuit Malfunction
Insufficient Coolant Temp. for Closed Engine coolant temp. sensor
 Cooling system Engine Coolant Temp. Circuit
Malfunction
 Open or short in throttle position sensor circuit
 Throttle position sensor
 ECM
 Throttle position sensor
 Open or short in heated oxygen sensor circuit
 Heated oxygen sensor
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.
IN−22− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
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.

Downloaded from www.Manualslib.com manuals search engine − INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−23
1996 TOYOTA T100 (RM449U)
5. PROBLEM SYMPTOMS TABLE
The suspect circuits or parts for each problem symptom are shown in the table below. Use this table to trou-
bleshoot the problem when a ”Normal” code is displayed in the diagnostic trouble code check but the prob-
lem 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 AreaSee 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 circuit1. Fuel pump control circuitST − 2, ST − 17
DI − 101
DI − 104
IN − 28
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 circuit1. 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)
DI − 101 DI − 173
DI − 104 DI − 173
DI − 104 DI − 104
DI − 173
DI − 104
 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.
AC − 85 EM − 3

Downloaded from www.Manualslib.com manuals search engine V08423 Knock Sensor 1
GRECM
KNK
E1 12
E6
WIRING DIAGRAM
 Wiring Diagram
DTC P0325Knock 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
P0325No 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.
This shows a wring diagram of the circuit.
Use the diagram together with ELECTRICAL
WIRING DIAGRAM to thoroughly understand the
circuit.
Wiring 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
The first letter indicates the basic wire color and
the second letter indicates the color of the stripe. IN−24
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
6. CIRCUIT INSPECTION
How to read and use each page is shown below.

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LOCK
KNK
E6 Connector
(a) Remove the glove compartment (See page SF − 37).
(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 − 34). Measure resistance between terminal KNK of ECM connector
and body ground.
Resistance: 1 MΩ or higher
Connector being checked is connected.  Indicates the condition of the connector of ECU during the check.
PREPARATION:
CHECK:
2Go 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
LOCKIgnition Switch ON
Ignition Switch ACC
STARTON
ACC
 Inspection Procedure
 Indicates the place to check the voltage or resistance.
 Indicates the connector position to 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 KNKWire Harness
E6 Connector KNK
A00255 AB0117
A00265
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.
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−25
1996 TOYOTA T100 (RM449U)

Downloaded from www.Manualslib.com manuals search engine FI0046
FI0047
FI0048
IN02K−03
IN−26− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
HOW TO USE THE DIAGNOSTIC
CHART AND INSPECTION
PROCEDURE
1. CONNECTOR CONNECTION AND TERMINAL IN-
SPECTION
For troubleshooting, diagnostic trouble code charts or
problem symptom table are provided for each circuit with
detailed inspection procedures on the following pages.
When all the component parts, wire harnesses and con-
nectors of each circuit except the ECU are found to be
normal in troubleshooting, then it is determined that the
problem is in the ECU. Accordingly, if diagnosis is per-
formed without the problem symptoms occurring,refer to
step 8 to replace the ECU, even if the problem is not in the
ECU. So always confirm that the problem symptoms are
occurring, or proceed with inspection while using the
symptom simulation method.
The instructions ”Check wire harness and connector” and
”Check and replace ECU” which appear in the inspection
procedure, are common and applicable to all diagnostic
trouble codes. Follow the procedure outlined below
whenever these instructions appear.
OPEN CIRCUIT:
This could be due to and a disconnected wire harness, faulty
contact in the connector, a connector terminal pulled out, etc.
HINT:
It is rarely the case that a wire is broken in the middle of
it. Most cases occur at the connector. In particular, care-
fully check the connectors of sensors and actuators.
Faulty contact could be due to rusting of the connector
terminals, to foreign materials entering terminals or a de-
formation of connector terminals between the male and
female terminals of the connector. Simply disconnecting
and reconnecting the connectors once changes the
condition of the connection and may result in a return to
normal operation. Therefore, in troubleshooting, if no ab-
normality is found in the wire harness and connector
check, but the problem disappears after the check, then
the cause is considered to be in the wire harness or con-
nectors.
SHORT CIRCUIT:
This could be due to a connect between the wire harness and
the body ground or to a short occurred inside the switch etc.
HINT:
When there is a short circuit between the wire harness and body
ground, check thoroughly whether the wire harness is caught
in the body or is clamped properly.

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Sensor Side
ECU Side
IN0378
Sensor SideECU Side
IN0380
Sensor SideECU Side
IN0381
Pull Lightly
Looseness of Crimping
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−27
1996 TOYOTA T100 (RM449U)
2. CONTINUITY CHECK (OPEN CIRCUIT CHECK)
(a) Disconnect the connectors at both ECU and sensor
sides.
(b) Measure the resistance between the applicable terminals
of the connectors.
HINT:
Measure the resistance while lightly shaking the wire har-
ness vertically and horizontally.
When tester probes are inserted into a connector, insert
the probes from the back. For waterproof connectors in
which the probes cannot be inserted from the back, be
careful not to bend the terminals when inserting the tester
probes.
3. RESISTANCE CHECK (SHORT CIRCUIT CHECK)
(a) Disconnect the connectors on both ends.
(b) Measure the resistance between the applicable terminals
of the connectors and body ground. Be sure to carry out
this check on the connectors on both ends.
Resistance: 1 MΩ or higher
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
4. VISUAL CHECK AND CONTACT PRESSURE CHECK
(a) Disconnect the connectors at both ends.
(b) Check for rust or foreign material, etc. in the terminals of
the connectors.
(c) Check crimped portions for looseness or damage and
check if the terminals are secured in lock portion.
HINT:
The terminals should not come out when pulled lightly.
(d) Prepare a test male terminal and insert it in the female ter-
minal, then pull it out.
NOTICE:
When testing a gold−plated female terminal, always use a
gold−plated male terminal.
HINT:
When the test terminal is pulled out more easily than others,
there may be poor contact in that section.