2. CHECK FUEL PRESSURE
(a) Check that the battery voltages is above 12 volts.
(b) Disconnect the negative (±) terminal cable from the
battery.
CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº
position and the negative (±) terminal cable is discon±
nected from the battery.
If there is no pressure, check the following parts:
wFusible link
wFuses (AM2 30A, EFI 15A, IGN 7.5A)
wEFI main relay
wFuel pump
wWiring connections (c) Check that there is pressure in the hose from the fuel
filter.
HINT: At this time, you will hear fuel return noise.
(e) Remove the SST.
SST 09843±18020 (d) Turn the ignition switch OFF.
± 5S±FE ENGINEMFI/SFI SYSTEMEG1±178
9=4 ±01
ELECTRIC COOLING FAN COMPONENTS
INSPECTION
1. INSPECT ENGINE COOLANT TEMPERATURE
SWITCH
(a) Using an ohmmeter, check that there is no continuity
between the terminals when the engine coolant tem±
perature is above 93C (199F).
(b) Using an ohmmeter, check that there is continuity
between the terminals when the engine coolant tem±
perature is below 83C (181 F).
If continuity is not as specified, replace the switch. 2. DISCONNECT ENGINE COOLANT TEMPERATURE
SWITCH CONNECTOR
Check that the cooling fan rotates.
If not, check the cooling fan relay, cooling fan, engine
main relay and fuse, and check for a short circuit
between the cooling fan relay and engine coolant
temperature switch.
3. CONNECT ENGINE COOLANT TEMPERATURE
SWITCH CONNECTOR
ON±VEHICLE INSPECTION
Low Temperature (Below 83
C (181F))
1. TURN IGNITION SWITCH ªONº
Check that the cooling fan stops.
If not, check the cooling fan relay and engine coolant
temperature switch, and check for a separated con±
nector or severed wire between the cooling fan relay
and engine coolant temperature switch.
High Temperature (Above 93C (199F))
4. START ENGINE
(a) Raise engine coolant temperature to above 93C
(199F).
(b) Check that the cooling fan rotates.
If not, replace the engine coolant temperature switch.
± 5S±FE ENGINECOOLING SYSTEMEG1±262
DIAGNOSIS SYSTEM
DESCRIPTION
The ECM contains a built±in self±diagnosis system by which
troubles with the engine signal network are detected and a
Malfunction indicator lamp on the instrument panel lights up.
By analyzing various signals as shown in the later table (See
page EG1±300) the Engine Control Module (ECM) detects
system malfunctions relating to the sensors or actuators.
In the normal mode, the self±diagnosis system monitors 14
items, indicated by code No. as shown in EG1±300. A mal-
function indicator lamp informs the driver that a malfunction
has been detected. The light goes off automatically when the
malfunction has been repaired. But the diagnostic trouble
code(s) remains stored in the ECM memory (except for code
Nos. 16). The ECM stores the code(s) until it is cleared by
removing the EFI fuse with the ignition switch off.
The diagnostic trouble code can be read by the number of
blinks of the malfunction indicator lamp when TE1 and E1
terminals on the data link connector 1 or 2 are connected.
When 2 or more codes are indicated, the lowest number
(code) will appear first.
In the test mode, 9 items, indicated by code No. as shown in
EG1±300 are monitored. If a malfunction is detected in any
one of the systems indicated by code Nos. 13, 22, 24, 25, 26,
27, 31, 41 and 71 the ECM lights the malfunction indicator
lamp to warn the technician that malfunction has been de-
tected. In this case, TE2 and E1 terminals on the data link
connector 1 or 2 should be connected as shown later. (See
page EG1±298).
In the test mode, even if the malfunction is corrected, the
malfunction code is stored in the ECM memory even when
the ignition switch is off (except code Nos. 43 and 51). This
also applies in the normal mode. The diagnostic mode (nor-
mal or test) and the output of the malfunction indicator lamp
can be selected by connecting the TE1, TE2 and E1 termi-
nals on the data link connector 1 or 2, as shown later.
A test mode function has been added to the functions of the
self±diagnostic system of the normal mode for the purpose of
detecting malfunctions such as poor contact, which are diffi-
cult to detect in the normal mode. This function fills up the
self±diagnosis system. The test mode can be implemented
by the technician following the appropriate procedures of
check terminal connection and operation described later.
(See page
EG1±298)
± 5S±FE ENGINEDIAGNOSIS SYSTEMEG1±296
ECM DATA MONITOR USING TOYOTA
HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the D LC2.
2. Monitor the ECM data by following the prompts on the
tester screen.
HINT: TOYOTA hand±held tester has a ªSnapshotº
function which records the monitored data.
Please refer to the TOYOTA hand±held tester operator's
manual for further details.
ECM TERMINAL VALUES MEASUREMENT
USING TOYOTA BREAK±OUT±BOX AND
TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA break±out±box and TOYOTA
hand±held tester to the vehicle.
2. Read the ECM input/output values by following the
prompts on the tester screen.
HINT: TOYOTA hand±held tester has ªSnapshotº func±
tion. This records the measured values and is effective in
the diagnosis of intermittent problems.
Please refer to the TOYOTA hand±held tester/Toyota
break±out±box operator's manual for further details.
DIAGNOSTIC TROUBLE CODE CLEARANCE
1. After repair of the trouble areas, the diagnostic trouble
code retained in the ECM memory must be cleared out by
removing the E F I fuse (15A) from J/13 No. 2 for 10 seconds or
more, with the ignition switch OFF.
HINT:
wCancellation can also be done by removing the battery
negative (±) terminal, but in this case, other memory
systems (clock, etc.) will also be cancelled out.
wIf it is necessary to work on engine components requir±
ing removal of the battery terminal, a check must first
be made to see if a diagnostic trouble code has been
recorded.
2. After cancellation, road test the vehicle to check that a
normal code is now read on the malfunction indicator
lamp.
If the same diagnostic trouble code appears, it indicates
that the trouble area has not been repaired thoroughly.
DIAGNOSTIC TROUBLE CODE CHECK
USING TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Read the diagnostic trouble codes by following the
prompts on the tester screen.
Please refer to the TOYOTA hand±held tester operator's
manual for further details.
± 5S±FE ENGINEDIAGNOSIS SYSTEMEG1±299
Disconnect the EFI fuse (15A) for 10 sec. or more, with IG switch OFF.
Initiate test mode (Connect terminal TE2 and E1 of data link connector 1 or 2 with IG switch
OFF).
Start the engine and warm up with all ACC switch OFF.
After the engine is warmed up, let it idle for 3 min.
After performing the idling in (3) , perform gradual acceleration with in the range
1,300~1,700 rpm (centered around 1,500 rpm) with the A/C switch ON and D position for A/T
(5th for M /T).
(Take care that the engine speed does not fall below 1,200 rpm when shifting. Gradually
depress the accelerator pedal and keep it. Steady so that engine braking does not occur).
Maintain the vehicle speed at 40 ± 50 mph (64 ± 80 km/h).
Keep the vehicle running for 1 ± 2 min. after starting acceleration.
HINT: If a malfunction exists, the malfunction indicator lamp will light up after approx.
60 sec. from the start of acceleration.
NOTICE: If the conditions in this test are not strictly followed, detection of the mal-
function will not be possible.
CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is
recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diag-
nostic trouble code is no longer detected.
Malfunction: Main Oxygen Sensor Deterioration
± 5S±FE ENGINECIRCUIT INSPECTIONEG1±353
H I NT: Before this test, check the feedback voltage for oxygen sensor.
Disconnect the EFI fuse (15 A) for 10 sec. or more, with IG switch OFF.
Initiate test mode (Connect terminal TE2 and E1 of data link connector 1 or 2 with
IG switch OFF).
Start engine and warm up.
After the engine is warmed up, let it race at 2,500 rpm for 3 min.
After performing the racing in (3) , perform idling 1 min.
HINT: If a malfunction exists, the malfunction indicator lamp will light up during step (4).
NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction
will not be possible.
CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diagnostic
trouble code is no longer detected.
Malfunction: Open or Short in Main Oxygen Sensor.
Open or Short in Injector Circuit, Injector Leak or Blockage.
± 5S±FE ENGINECIRCUIT INSPECTIONEG1±364
Disconnect the E F I fuse (15 A) for 10 sec. or more, with IG switch OFF.
Initiate test mode (Connect terminals TE2 and E1 of data link connector 1 or 2
with I G switch OFF).
Start the engine and warm up, with all ACC switch OFF.
After the engine is warmed up, let it drive at 50 ~ 55 mph (80 ~ 88 km/h)
for 10 min. or more.
After driving, stop at a safe place and perform idling for 2 min. or less.
After performing the idling in (4) , perform acceleration to 60 mph (96 km/h)
with the throttle valve fully open.
HINT: If a malfunction exists, the malfunction indicator lamp will light up during
step.
NOTICE: If the conditions in this test are not strictly followed, detection of the
malfunction will not be possible.
CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is
recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diagnos±
tic trouble code is no longer detected.
Malfunction: Open or Short in Sub Oxygen Sensor
± 5S±FE ENGINECIRCUIT INSPECTIONEG1±370
Disconnect the EFI fuse (15 A) for 10 sec. or more, with IG switch OFF. Initiate
test mode (Connect terminals TE2 and E1 of data link connector, 1 or 2 with IG
switch OFF).
CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is
recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diag-
nostic trouble code is no longer detected.
Malfunction: Open in EGR gas temp. sensor circuit
Start the engine and warm up.
After the engine is warmed up, let it idle for 3 min.
With the A/C ON and transmission in 5th gear A/T in ªDº position), drive at
55 ± 60 mph (88 ± 96 km/h) for 4 min. or less.
HINT: If a malfunction exists, the malfunction indicator lamp will light up dur-
ing step (4) .
NOTICE: If the conditions in this test are not strictly observed, detection of
the malfunction will not be possible.
± 5S±FE ENGINECIRCUIT INSPECTIONEG1±391