1987 TOYOTA CELICA sensor

EFI SYSTEM - Diagnosis System
. .
DIAGNOSIS SYSTEM
__ --
FL25
(MA)
The ECU contains a built-in self-diagnosis system by which
troubles with the engine signal network are detected and a
“CHECK ENGINE” warning light on the instrument panel
flashes,
By analyzing various signals as shown in the later table (See
pages Fl-30, 31) the Electronic Control Unit (ECU) detects
system malfunctions which are related to the various operating
parameter sensors or to the actuator. The ECU stores the
failure until the diagnosis system is cleared by removing the EFI
fuse with the ignition switch off.
A “CHECK ENGINE” warning light on the instrument panel
informs the driver that a malfunction has been detected.
The light goes out automatically when the malfunction has
been cleared.
The diagnostic code can be read by the number of the blinks of
the “CHECK ENGINE” warning light when T and El are short-
circuit.
(MS)
The ECU contains a built-in self-diagnosis system by which
troubles with the engine signal network are detected and a
“CHECK ENGINE” warning light on the instrument panel
flashes.
By analyzing various signals as shown in the later table (See
page FI-32) the Electronic Control Unit (ECU) detects system
malfunctions which are related to the various operating
parameter sensors or to the actuator. The ECU stores the
failure until the diagnosis system is cleared by removing the EFI
fuse with the ignition switch off.
In the ECU, a test mode function has been added to the func-
tions of the self-diagnosis system of the previous diagnosis
mode (normal mode) for the purpose of detecting malfunctions
such as poor contact which are difficult to detect in the normal
mode. This function fills up the self-diagnosis system. The test
mode can be implemented by the technician to follow the pro-
cedures of appropriate check terminal connection and opera-
tion described in later (See page FI-28).
In the normal mode, the self-diagnosis system monitors 14
items, indicated by the codes except for code No. 51 as shown
in FI-32. A “CHECK ENGINE” warning light on the instrument
panel informs the driver that a malfunction has been detected.
The light goes out automatically when the malfunction has
been cleared.
The diagnostic code can be read by the number of the blinks of
the “CHECK ENGINE” warning light when TEl and El are
short-circuited.

FI-26 EFI SYSTEM - Diagnosis System
-.
i
“CHECK ENGINE” Warning Light In the test mode, seven items, indicated by code
24, 41, 42, 43, and 5 1, as shown in FI-32 are m
malfunction is detected in any one of the systems
code Nos. 13, 22, 24, and 41 the ECU lights the “CHECK
ENGINE” warning light to warm the technician that the mal-
function has been detected. In this case, TE2 and El terminals
on the check connector should be connected as shown later
(See page FI-28)
In the test mode, for all seven conditions shown above in code
Nos. 13 - 51, even if the malfunction is corrected, the mal-
function is stored in the ECU memory while the ignition switch
remains on. Also, when a malfunction occurs for-the four con-
ditions from code Nos. 13 - 41, the “CHECK ENGINE” warning
light remains on. However, once the ignition switch is turned to
OFF, the ECU erases all of the malfunctions in the memory. The
diagnostic mode (normal or test) and the output of the “CHECK
ENGINE” warning light can be selected by the TEl , TE2 and El
terminal connections on the check connector, as shown in the
later.
“CHECK ENGINE” WARNING LIGHT CHECK
1. The “CHECK ENGINE” warning light will come on when
the ignitiorqw:@ch is placed at ON and the engine is not
running. -y.
2. When the engine is started, the “CHECK ENGINE” warning
light should go out.
If the light remains on, the diagnosis system has detected
a malfunction or abnormality in the system.
OUTPUT OF DIAGNOSIS CODES
(MA)
To obtain an output of diagnostic codes, proceed as follows:
1. Initial conditions ,’
(a)’ Battery voltage about 11 volts
(b) Throttle valve fully closed (throttle position sensor
IDL points closed)
(cl Transmission in neutral position
(d) Accessory switches OFF
2. Turn the ignition switch to ON. Do not start the engine.

EFI SYSTEM; Diagnosis System
S)
------) -.
I Fl281
Test mode
i
To obtain an output of diagnostic codes, proceed as follows:
1. Initial conditions
(a) Battery voltage about 1 1 volts
(b) Throttle valve fully closed (throttle position sensor
IDL points closed)
(c) Transmission in neutral position
(d) Accessory switches OFF
2. Using a service wire, short terminals TE2 and El of the j
check connector.
-----.-q
*-heengine and run the vehicle at a speed of IO km/h I
(6 mph) or higher. __-- /---’
_ ___ _.--.--.
4. Simulate the conditions of the malfunction described by
the user.
5. Using a service wire, short terminals TEl and .El of the
check connector.
NOTE:
l The test mode will not start if terminals TE2 and El are con-
nected after the ignition switch is turned on, or terminals TE2
and El are connected after terminals TEI and El are con-
nected.
l
0 The starter signal and vehicle speed signal will be diagnosed
by the ECU as malfunctions, and codes No. 42, and 43 will
be output, if the operation in 3. above is not performed.
6. Read the diagnosis code as indicated by the number of
flashes of the “CHECK ENGINE” warning light.
(See page FI-27)
7. After the diagnosis check, remove the service wires.

I-30 .EFl SYSTE.M - Diagnosis System
DIAGNOSTIC CODES (MA)
Trouble area
I See
page Code Number of
; No. Che;;;;gine System
I
- nnrulno4 Norma’ Diagnosis
This appears when none of
the other codes area identified.
0
Ignition switch circuit
Ignition switch T
Main relay circuit
1 Main relay
1 ECU FI-41
1 Distributor circuit
r Distributor
) Starter signal circuit
b ECU
) Distributor circuit
B Distributor
B ECU IG-3
IG-3 ECU (+B) fl n Momentary interruption in 0
11
power supply to ECU.
I 0
l
Jo “NE” or “G” signal to
ICU within 2 seconds after
engine has been cranked.
Uo “NE” signal to ECU when
sngine Sp88d is above
1,000 rpm.
No “IGF” signal to ECU
i- 8 times in succession.
Ietectinn of oxygen sensor
jeterioration. E
t
C
i
P. Open or short circuit in wate
temp. sensor signal.
Open or short circuit in intake
air temp. sensor signal.
I7M-GE)
Air-flow
Meter Signal Open circuit in VC signal or
short circuit between VS and
E2 when idle contacts are
c tosed.
(7M-GTE)
Open or Short circuit in air
flow meter signal.
(‘IM-GE)
Open circuit in E2 or short
circuit between VC and VS.
(‘IM-GTE)
Open or short circuit in HAC
sensor signal
Turbocharger
Pressure ‘3
Turbocharger pressure is
abnormal. B Ignition and ignition coil
circuit
8 Igniter and ignition coil
0 ECU !I-5 1
gnition Signal
l-l 2
FI-4’
Fl-48
I!
(
!
1
,-
1
Fll608
nn n
FIl609
FI-44
d )r FI-4‘
FI-51
Open or short circuit in circuit
I Sensor Signal throttle position sensor signal. 0 Throttle position sensor
0 ECU
SHl,d , FI-4 0 Oxygen sensor circuit
l Oxygen sensor
0 ECU
0 Water temp. sensor
@muit
‘8 Water temp. sensor
l ECU
0 Intake air temp. sensor
circuit
8 Intake air temp. sensor
. ECU 3xygen Sensor
signal
Water Temp.
Sensor Signal Fll81t
Intake Air Tern
Sensor Signal 24
Fll81
0 Air flow meter circuit
0 Air flow meter
0 ECU
Fl161 0 Air flow meter Circuit
0 Air flow meter
0 ECU
0 HAC sensor circuit
l HAC sensor
l ECU
0 Turbocharger
8 Air flow meter
0 Intercooler system
0 ECU (‘IM-GE)
Air Flow
Meter Signal
(7M-GTE)
HAC Sensor
Signal Fl18
i-
,
0 Throttle position s8nsC I FIZE
n

EFI SYSTEM
- Diagnosis System
FI-31
DIAGNOSTIC CODES (MA) (Cont’d) __
:odc
No. Number of
Check engine
blinks Diagnosis System See
page
FL50 Trouble area
l Vehicle speed sensor
circuit
l Vehicle speed sensor
. ECU ’
I
l Ignition switch circuit
l Ignition switch
l ECU
l Knock sensor circuit
l Knock sensor
l ECU
. ECU
l A/C switch circuit
l A/C switch ‘“q
l A/C am&fire
l Neutral start switch
circuit ’
l Neutral start switch
0 Throttle position sensor
circuit
l Throttle position sensor
l ECU Vehicle Speed
Sensor Signal
Starter Signal No “SPD” signal for 5
seconds when engine speed
is between 2,500 rpm and
4,500 rpm and coolant temp.
is below 80°C (176’F) except
when racing the engine.
No “STA” signal to ECU until
engine speed reaches 800
rpm with vehicle not moving.
Knock Sensor
Signal Open or short circuit in knock
sensor signal. 42
FI161
FHBl
Fl181
FIlei
52
Knock control in ECU faulty. Knock Control
signal in ECU
No “IDL” signal, “NSW”
signal or “A/C” signal to
ECU, with check terminals
El and T shorted. Switch Signal
‘1 WI TWC vehicles only
‘2 7M-GTE only
“3 Abnormalities in the air flow meter may also be detected.
DIAGNOSTIC CODES (MS)
Number of
Check engine
System
blinks
m Normal
fl1604
nn ECU (B) Diagnosis
This appears when none of
the other codes are identified.
Momentary interruption in
power supply to ECU. Trouble area See
page
l Ignition switch circuit
l Ignition switch
l Main relay circuit
l Main relay
l ECU FI-62
l Distributor circuit
0 Distributor
l Starter signal circuit
. ECU IG-3
l Distributor circuit
l Distributor
. ECU IG-3
l Igniter and ignition coil 11
FI1605
n nn RPM Signal No “NE” or “G” signal to
ECU within 2 seconds after
engine has been cranked.
FHBOB
nnnn, RPM Signal No “NE” signal to ECU when
engine speed is above
Fl1807 1,000 rpm. 12
-
13
-
14
-LJUlJUL 1 Ignition Signal 1 * No. “IGF” signal to ECU
6 - 8 times in succession. circuit
0 Igniter and ignition coil
. ECU
.t Fl-70

FI-32 EFI SYSTEM - Diagnosis System
1 ode -
: Number of See
Check engine System Diagnosis Trouble area
paw
blinks
0 Water temp. sensor
. .
clrcult m n FI-68
0 Water temp. sensor
0 ECU _
FllBlO 0 Intake air temp. sensor
r
JUMJJJL Intake Air Temp. Open or short circuit in intake circuit
FI-67
Sensor Signal air temp. sensor signal. 0 intake air temp. sensor
. ECU
fll611
Open circuit in VC signal or
0 Air flow meter circuit
JJJJ n f
‘. ‘( <;
closed.
F11612 .
i Air flow meter circuit
DIAGNOSTIC CODES (MS) (Cont’d)
4-65
32
Fl1613 I I
I 0 Throttle position sensor
Open or short circuit in circuit
41 throttle position sensor signal.
! 0 Throttle position sensor
. ECU
Fl1614
No “SPD” signal for 5
seconds when engine speed
0 Vehicle speed sensor
42 nnnruvl
is below 80°C (176°F) except
when racing the engine.
fl16151
I
No “STA” sianal to ECU until 0 Ignition switch circuit
43
i m Starter Signal /~~n~i,‘,pee~;~ct-;~~~ng : ;;;on switch FI-6!
FM
FM
? -. Fl1616 .^
0 Knock sensor circuit
52
.I JjJJMJjn Eyn$ Sensor ~~n~op:~~ circuit in knock : :gk sensor
53
I F11616
w6,9 Kn$c~i~“,“,‘;“’ Knock control in ECU faulty. l ECU
0 A/C compressor relay
A/C Com-
Open or short circuit in circuit
pressor
Relay Signal A/C compressor relay signal. a A/C compressor relay
. ECU
f12611
0 A/C switch circuit Z
51
No “IDL” signal, “NSW” 0 A/C switch
0 A/C amplifire l Neutral start switch
circuit
0 Neutral start switch
0 Throttle position sensor
circuit
I F11617
0 Throttle position Sensor
. ECU

EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MA)
FI-35
. .
EFI SYSTEM CHECK PROCEDURE
NOTE:
l Perform all voltage measurements with the connectors
connected.
0 Verify that the battery voltage is 11V or above when
the ignition switch is at “ON”.
Using a voltmeter with high-impedance (IO kQ/V
minimum), measure the voltage at each terminal of the
wiring connectors.
I ) ECU +B
Terminals of ECU (7M-GE)
Symbol ) Terminal Name
E01 POWER GROUND
E02 POWER GROUND
No. 10 INJECTOR (No. 1 and 4)
No. 20 INJECTOR (No. 2 and 6)
STA STARTER SWITCH
No. 30 INJECTOR (No. 3 and 5)
STJ COLD START INJECTOR
El COMPUTER GROUND
NSW NEUTRAL START SWITCH (A/T)
N/C *CLUTCH SWITCH (M/T) 1 Symbol) Terminal Name
T CHECK CONNECTOR
G2 DISTRIBUTOR
VTA THROTTLE POSITION SENSOR
NE DISTRIBUTOR
IDL THROTTLE POSITION SENSOR
IGT IGNITER
IGF IGNITER
THW WATER TEMP. SENSOR Symbol
Terminal Name
L3 ECT COMPUTER
EGR
vsv (EGR)
A/C A/C MAGNET SWITCH
SPD SPEEDOMETER
W WARNING LIGHT
FPR FUEL PUMP RELAY
DFG
DEFOGGER RELAY
THA
AIR TEMP. SENSOR
ECT
ECT COMPUTER
vs AIR FLOW METER
KNK KNOCK SENSOR LP HEADLIGHT RELAY
ISC 1 ISC MOTOR NO. 1 COIL ox OXYGEN SENSOR vc THROTTLE POSITION SENSOR
AIR FLOW METER
ISC 3 ISC MOTOR NO. 3 COIL E2 SENSOR GROUND
ISC 2 ISC MOTOR NO. 2 COIL VSV 1 VSV (AIR CONTROL)
BATT BATTERY
ISC 4 ISC MOTOR NO. 4 COIL Ll ECT COMPUTER +B EFI MAIN RELAY
GQ DISTRIBUTOR VSVP VSV (FPU) IG S/W IGNITION SWITCH
VF CHECK CONNECTOR
Gl DISTRIBUTOR
ECU Terminals 1 L2 ECT COMPUTER
+Bl EFI MAIN RELAY
1 M-REL EFI MAIN RELAY (COIL)
*For cruise control
F10574

FI-36 EFI SYSTEM - Troubleshooting with VoltjOhmmeter (MA)
Terminals of ECU. (7M;GTE)
Symbol Terminal Name Symbol Terminal Name Symbol Terminal Name
EOI POWER GROUND G2 CAM POSITION SENSOR A/C A/C MAGNETIC SWITCH
E02 POWER GROUND VTA
THROTTLE POSITION SENSOR SPD SPEEDOMETER
No, 10 INJECTOR (No. 1 and 4)
NE CAM POSITION SENSOR W
WARNING LIGHT
No. 20 INJECTOR (No. 2 and 6) IDL
THROTTLE POSITION SENSOR FPR FUEL PUMP RELAY
STA STARTER SWITCH IGT IGNITER OIL OIL PRESSURE SWITCH
No. 30 INJECTOR (No. 3 and 5) IGdA IGNITER THA AIR TEMP. SENSOR
STJ COLD START INJECTOR
IGF IGNITER ECT ECT COMPUTER
rEl COMPUTER GROUND KNKl KNOCK SENSOR
t HAC 1 tl
NSW
NEUTRAL START SWITCH (A/T) THW WATER TEMP. S
N/C ‘CLUTCH SWITCH (M/T) KNK2 KNOCK SENSOR 1 vc ) THROTTLE
AIR
FLOW I
LTITUDE COMPENSATION
, .xNSOR
ENSOR 1 FC 1 CIRCUITOPENING RELAY I
IGdB IGNITER ox OXYGEN SENSOR KS AIR FLOW METER
ISC 1 ISC MOTOR NO. 1 COIL E2 SENSOR GROUND BATT BATTERY
r
ISC 3 ISC MOTOR NO. 3 COIL
vsv VSV (FPU) +B EFI MAIN RELAY
ISC 2 ISC MOTOR NO. 2 COIL Ll ECT COMPUTER IG S/W IGNITION SWITCH
ISC 4 ISC MOTOR NO. 4 COIL HT OXYGEN SENSOR +Bl EFI MAIN RELAY
GO CAM POSITION SENSOR L2 ECT COMPUTER TIL
TURBO INDICATOR
VF CHECK CONNECTOR M-REL
EFI MAIN RELAY (COIL) DFG DEFOGGER RELAY
Gl CAM POSITION SENSOR L3 ECT COMPUTER LP HEADLIGHT RELAY
T CHECK CONNECTOR
EGR VSV (EGR)
ECU Terminals
E2 Ll L2 L3 A/C W OIL ECT FC KS +B +Bl
+
F10574 Fll 99:
*For cruise control