1996 TOYOTA T100 engine

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.

Downloaded from www.Manualslib.com manuals search engine V08425
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.

Downloaded from www.Manualslib.com manuals search engine IN0379
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.

Downloaded from www.Manualslib.com manuals search engine FI7187
Z17004
CB
AOPENSensor Fig. 1 ECU
1
21
21
221
Z17005
Fig. 2
SensorECU
C
BA1
21
21
2
B04722
Fig. 3
ECU
Sensor
21A B1 C
1
1
221
2 B2
IN−28− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TOYOTA T100 (RM449U)
5. CONNECTOR HANDLING
When inserting tester probes into a connector, insert them from
the rear of the connector. When necessary, use mini test leads.
For water resistant connectors which cannot be accessed from
behind, take good care not to deform the connector terminals.
6. CHECK OPEN CIRCUIT
For the open circuit in the wire harness in Fig.1, perform ”(a)
Continuity Check” or ”(b) Voltage Check” to locate the section.
(a) Check the continuity.
(1) Disconnect connectors ”A” and ”C” and measure
the resistance between them.
In the case of Fig.2,
Between terminal 1 of connector ”A” and terminal 1
of connector ”C” → No continuity (open)
Between terminal 2 of connector ”A” and terminal 2
of connector ”C” → Continuity
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.
(2) Disconnect connector ”B” and measure the resis-
tance between the connectors.
In the case of Fig.3,
Between terminal 1 of connector ”A” and terminal 1
of connector ”B1” → Continuity
Between terminal 1 of connector ”B2” and terminal
1 of connector ”C” → No continuity (open)
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ”B2” and terminal
1 of connector ”C”.

Downloaded from www.Manualslib.com manuals search engine Z17007
Fig. 4
Sensor
CA1
21
21
2ECU
B
5 V
5 V0 V5 V
Z17008
CBASHORT
Fig. 5
1
21
22 1
Z17009
Fig. 6
SensorECU
CB
A1
21
21
2
− INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−29
1996 TOYOTA T100 (RM449U)
(b) Check the voltage.
In a circuit in which voltage is applied (to the ECU connec-
tor terminal), an open circuit can be checked for by con-
ducting a voltage check.
As shown in Fig.4, with each connector still connected,
measure the voltage between body ground and terminal
1 of connector ”A” at the ECU 5V output terminal, terminal
1 of connector ”B”, and terminal 1 of connector ”C”, in that
order.
If the results are:
5V: Between Terminal 1 of connector ”A” and Body Ground
5V: Between Terminal 1 of connector ”B” and Body Ground
0V: Between Terminal 1 of connector ”C” and Body Ground
Then it is found out that there is an open circuit in the wire har-
ness between terminal 1 of ”B” and terminal 1 of ”C”.
7. CHECK SHORT CIRCUIT
If the wire harness is ground shorted as in Fig.5, locate the sec-
tion by conducting a ”continuity check with ground”.
Check the continuity with ground.
(1) Disconnect connectors ”A” and ”C” and measure
the resistance between terminal 1 and 2 of connec-
tor ”A” and body ground.
In the case of Fig.6
Between terminal 1 of connector ”A” and body
ground → Continuity (short)
Between terminal 2 of connector ”A” and body
ground → No continuity
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.