IN-26 TOYOTA TERCEL 1996 Service Repair Manual

Diagnostic trouble code check
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 TERCEL (RM440U)
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 table.

FI0048
FI0047
FI0046
IN05X-13
IN-26- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1996 TERCEL (RM440U)
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. So always confirm that the
problem symptoms are occurring, or proceed with inspec-
tion while using the symptom simulation method.

The instructions ºCheck wire harness and connectorº and
ºCheck and replace ECUº 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 a disconnected wire harness, faulty con-
tact 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. 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 contact between wire harness and the
body ground or to a short circuit 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.

- DIAGNOSTICSENGINE
DI-7
1996 TERCEL (RM440U)
(b) Clear the DTC.
The following actions will erase the DTC and freezed
frame data.
(1) Operating the OBD II scan tool (complying with SAE
J1978) or TOYOTA hand-held tester to erase the
codes. (See the OBD II scan tool's instruction book
for operating instructions.)
(2) Disconnecting the battery terminals or EFI fuse.
NOTICE:
If the TOYOTA hand-held tester switches the ECM from
normal mode to check mode or vice-versa, or if the igni-
tion switch is turned from ON to ACC or OFF during check
mode, the DTC and freezed frame data will be erased.
4. FAIL-SAFE CHART
If any of the following codes is recorded, the ECM enters fail-safe mode.
DTC No.Fail-Safe OperationFail-Safe Deactivation Conditions
P0105Ignition timing fixed at 5° BTDCReturned to normal condition
P0110Intake air temp. is fixed at 20°C (68°F)Returned to normal condition
P0115Engine coolant temp. is fixed at 80°C (176°F)Returned to normal condition
P0120VTA is fixed at 0°
The following condition must be repeated at least 2 times
consecutively
When closed throttle position switch is ON:
0.1 V
VTA
0.95 V
P0141The heater circuit in which an abnormality is detected is
turned offIgnition switch OFF
P0325Max. timing retardationIgnition switch OFF
P1300Fuel cutIGF signal is detected for 4 consecutive ignitions
5. CHECK FOR INTERMITTENT PROBLEMS
HINT:
TOYOTA hand-held tester only:
By putting the vehicle's ECM in check mode, 1 trip detection logic is possible instead of 2 trip detection logic
and sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
(a) Clear the DTC (See page DI-13).
(b) Set the check mode (See page DI-13).
(c) Perform a simulation test (See page IN-26).
(d) Check the connector and terminal (See page IN-26).
(e) Handle the connector (See page IN-26).
6. BASIC INSPECTION
When the malfunction code is not confirmed in the DTC check, troubleshooting should be performed in the
order for all possible circuits to be considered as the causes of the problems. In many cases, by carrying
out the basic engine check shown in the following flow chart, the location causing the problem can be found
quickly and efficiently. Therefore, use of this check is essential in engine troubleshooting.
1 Is battery positive voltage 11V or more when engine is stopped ?
NO Charge or replace battery.

DI4LI-02
- DIAGNOSTICSENGINE
DI-19
1996 TERCEL (RM440U)
PROBLEM SYMPTOMS TABLE
SymptomSuspect AreaSee page
Does not start (Engine does not crank)1. Starter and starter relayST-13
ST-31
Does not start (No combustion)1. ECM power source circuit
2. Fuel pump control circuitDI-97
DI-100
Does not start (No complete combustion)1. Fuel pump control circuitDI-100
Difficult to start (Engine cranks normally)
1. Starter signal circuit
2. Fuel pump control circuit
3. CompressionDI-90
DI-100
EM-3
Difficult to start (Cold engine)1. Starter signal circuit
2. Fuel pump control circuitDI-90
DI-100
Difficult to start (Hot engine)1. Starter signal circuit
2. Fuel pump control circuitDI-90
DI-100
Poor idling (High engine idle speed)1. A/C signal circuit
2. ECM power source circuitAC-66
DI-97
Poor idling (Low engine idle speed)1. A/C signal circuit
2. Fuel pump control circuitAC-66
DI-100
Poor idling (Rough idling)1. Compression
2. Fuel pump control circuitEM-3
DI-100
Poor idling (Hunting)1. ECM power source circuit
2. Fuel pump control circuitDI-97
DI-100
Poor driveability (Hesitation/Poor acceleration)
1. Fuel pump control circuit
2. A/T faulty (A132L)
A/T faulty (A242L)
3. A/C cut control circuitDI-100
AX-10
AX-13
DI-106
Poor driveability (Surging)1. Fuel pump control circuitDI-100
Engine stall (Soon after starting)1. Fuel pump control circuitDI-100
Engine stall (During A/C operation)1. A/C signal circuit
2. Engine control module (ECM)AC-66
IN-26

A15678
A15679
DI-22
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
2 Check voltage between terminals VC and E2 of ECM connector.
PREPARATION:
(a) Remove the lower finish panel.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals VC and E2 of the ECM
connector.
OK:
Voltage: 4.5 - 5.5 V
NG Check and replace ECM (See page IN-26).
OK
3 Check voltage between terminals PIM and E2 of ECM connector.
PREPARATION:
(a) Remove the lower finish panel.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals PIM and E2 of ECM con-
nector.
OK:
Voltage: 3.3 - 3.9 V
OK Check and replace ECM (See page IN-26).
NG
4 Check for open and short in harness and connector between manifold absolute
pressure sensor and ECM.
NG Repair or replace harness or connector.
OK
Replace manifold absolute pressure sensor.

A15681
A15682
DI-26
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the intake air temp. sensor connector.
(b) Connect sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Confirm good connection at sensor.
If OK, replace intake air temp. sensor.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Connect terminals THA and E2 of ECM connector togeth-
er.
HINT:
Intake air temperature sensor connector is disconnected. Be-
fore checking, do a visual and contact pressure check for the
ECM connector (See page IN-26).
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Open in harness between terminal E2 or termi-
nal THA, repair or replace harness.
NG
Confirm good connection at ECM.
If OK, replace ECM.

A15742
A15683
- DIAGNOSTICSENGINE
DI-27
1996 TERCEL (RM440U)
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the intake air temp. sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Replace intake air temp. sensor.
NG
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Disconnect the E7 connector of ECM.
HINT:
Intake air temperature sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN-26).

A15686
A15687
DI-30
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Connect terminals THW and E2 of ECM connector to-
gether.
HINT:
Engine coolant temperature sensor connector is disconnected.
Before checking, do a visual and contact pressure check for the
ECM connector (See page IN-26).
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Open in harness between terminal E2 or termi-
nal THW, repair or replace harness.
NG
Confirm good connection at ECM.
If OK, replace ECM.
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the engine coolant temperature sensor con-
nector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Replace engine coolant temperature sensor.
NG

A15688
- DIAGNOSTICSENGINE
DI-31
1996 TERCEL (RM440U)
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Disconnect the E7 connector of ECM.
HINT:
The engine coolant temperature sensor connector is discon-
nected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN-26).

A00369
1 (+) ON
S03529 BE6653A00854
ON
VTA (+) E2 (-)
- DIAGNOSTICSENGINE
DI-35
1996 TERCEL (RM440U)
2 Check voltage between terminal 1 of wire harness side connector and body
ground.
PREPARATION:
(a) Disconnect the throttle position sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal 1 of wire harness side
connector and the body ground.
OK:
Voltage: 4.5 - 5.5 V
NG Go to step 5.
OK
3 Check throttle position sensor (See page MF-26).
NG Replace throttle position sensor.
OK
4 Check voltage between terminals VTA and E2 of ECM connector.
PREPARATION:
(a) Remove the lower finish panel.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals VTA and E2 of the ECM
connector.
OK:
Throttle ValveVoltage
Fully closed0.3 - 1.0 V
Fully open3.2 - 4.9 V
NG Check for open and short in harness and con-
nector between ECM and throttle position sen-
sor (VTA or E2 line) (See page IN-26).
OK