TOYOTA CELICA 1987 Service Owners Manual

EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS) FI-57
-.
TROUBLESHOOTING WITH
VOLT/OHMMETER (MS)
NOTE: The following troubleshooting pro-
cedures are designed for inspection of each separ-
ate system, and therefore the actual procedure
may vary somewhat.. However, troubleshooting
should be performed refering to .the inspection
methods described in this manual. .._
Before beginning,inspection, it is best to first make
a simple check of the fuses, fusible links and the The following troubleshooting procedures are
based on the supposition that the trouble ‘lies in
either a short or open circuit in a component out-
side the computer or a short circuit within the
computer.
If engine trouble occurs even though proper.
operating voltage is detected in the computer con-
nector, then it can be assumed that the ECU is
faulty and should be replaced.
LOCATIoN- OF FUSES AND FUSIBLE LINKS
condition of the connectors.
Junction Block and Relay Block Cassettes

jS EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS)
-.
0
“B”
Fl294.
ECU
EFI SYSTEM CHECK PROCEDURE
._
PREPARATION
(a) Disconnect the connectors from the ECU.
(b) Remove the locks as shown in the illustration so that
the tester probe(s) can easily come in.
CAUTION: Pay attention to sections “A” and “B” in
the illustration which can be easily broken,
(c) Reconnect the connectors to the ECU.
’
NOTE:
0 Perform ail voltage measurements with the connectors
connected.
0 Verify that the battery voltage is 1 IV or above when
the ignition switch is at “ON”.
Using a voltmeter with high-impedance (10 kQ/V mihimum),
measure the voltage at each terminal of the wiring con-
nectors.
Terminals of ECU
rmbol Terminal Name Symbol Terminal Name
Symbol Terminal Name
EOI POWER GROUND NE DISTRIBUTOR ACPS A/C PRESSURE SWITCH
co2 POWER GROUND El COMPUTER GROUND SPD SPEEDOMETER
o. 10 INJECTOR (No. 1 and 4) VF CHECK CONNECTOR ECT ECT COMPUTER
o. 30 INJECTOR (No. 3 and 5)
GO DISTRIBUTOR ACR A/C COMPRESSOR
o. 20 INJECTOR (No. 2 and 6) TE2 CHECK CONNECTOR Ll
ECT COMPUTER
ELS DEFOGGER SWITCH
HEADLIGHT SWITCH TEl CHECK CONNECTOR L2
ECT COMPUTER
FPU VSV (FPU) KNK KNOCK SENSOR FPR FUEL PUMP RELAY
ACV VSV (A/R CONTROL) THW WATER TEMP. SENSOR L3 ECT COMPUTER
SC 1 ISC MOTOR NO. 1 COIL IDL
THROTTLE POSITION SENSOR W
WARNING LIGHT
IGT IGNITER THA AIR TEMP. SENSQR
M-REL EFI MAIN RELAY (COIL)
SC- ISC MOTOR NO. 2 COIL VTA THROlTLE POSITION SENSOR IG SiW IGNITION SWITCH 3
ISC3 ISC MOTOR NO. 3 COIL vs AIR FLOW METER Bl EFI MAIN RELAY
ISC4 ISC MOTOR NO. 4 COIL vcc AIR FLOW METER
THROTTLE POSITION SENSOR BATT BATTERY
IGF IGNITER E2
SENSOR GROUND B
EFI MAIN RELAY
G2 1 DISTRIBUTOR 1 STA 1 STARTER SWITCH
Gl 1 DISTRIBUTOR 1 NSW 1 NEUTRALSTARTSWITCH
ZU Terminals

EFI SYSTEM - Ttpbleshooting with Volt/Ohmmeter (MS)
FL59
IO.
I Terminals
BATT - El
IG S/W - El
M-REL - El
2P-
I UTA - E2
3
US - E2
THA - E2
THW - E2
.B / IGF, IGT - El
9 ISCI
lSC4 - El
10
I W - El
ECU Terminals
Voltage at ECU Wiring Connectors
Condition STD Voltage ’
10 - 14
ignition S/W ON
10 - 14
Throttle valve open 10 - 14
4-6
Ignition S/W ON .
Throttle valve fully closed 0.1 - 1.0
Throttle valve fully open
4-5
4-6
Ignition S/W ON Measuring plate fully closed
4-5
Measuring plate fully open
0.02 - 0.08
Idling 2-4
3,000 rpm 0.3 - 1 .o
Ignition S/W ON 9
- 14 FI-66
Ignition S/W ON Intake air temperature 20°C (68°F) 1
-3
Ignition S/W ON
Coolant temperature 80°C (176°F) 0.1 - 1.0
Cranking
6 - 14
Idling 0.7 - 1.0
Ignition S/W ON
9 - 14
No trouble (“CHECK-ENGINE” warning light off) and
engine running 8 - 14 See page
FI-60
FI-6 1
FI-62
FI-63
FI-64
Fl-65
Fl-6.7
FI-68
FI-69
Fl-70
FI-7 1
Fl;72

FI-60 EFI SYSTEM - Troubleshooting with VoW6hmmeter (MS)
-.
No. Terminals Trouble Condition .
STD Voltage
BATT - El No voltage
lo- 14v
IO S/W - El
1 No voltage
Ignition switch ON lo-14v
M-REL - El No voltage Ignition switch ON
IO- 14v
B(B1) -El No voltage Ignition switch ON
10 - 14 v
-‘- Battery BATT ’
Bl
B
M-REL
IG S/W
El
@z
ECU
Fl275:
I Fl275,
ECU w
I Fl275
. BATT - El
@There is no voltage between ECU terminals BATT and El.
I
I
I 0
Check that there is voltage between ECU terminal BATT and
body ground.
I
NO OK
0 Check wiring between ECU terminal El and body
ground.
BAD
Replace.
1 OK
Check wiring between ECU terminal BAD
and battery. w Repair or replace.

EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS) FI-61
-.
ECU @
I ECU I
I ECU
. IG S/W - El
._
0 There is no voltage between ECU terminals IG S/W and El.
(IG S/W ON)
I
I
0
Check that there is voltage between ECU terminal IG S/W and
body ground. (10 S/W ON)
, 1
1
Check wiring between ECU terminal El and body
ground.
I
,
I I
Check fuse, fusible link and
ignition switch. BAD
) Repair or replace.
l M-REL - El
0
There is no voltage between ECU terminals M-REL and El.
(IG S/W ON)
1
‘
3 Check that there is voltage between ECU terminal M-REL and
body ground. (IG S/W ON)
NO OK
Che’ck wiring between ECU terminal El and body
ground.
OK BAD
Try another ECU.
1 Replace or repair.
F I
I I BAD
c Replace. Check EFI main relay and wiring
harness.

FI-62 EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS)
ECU
Il--crl
I
I fl2911
I ECU @I
-- -
I’ I
II I R%
F12767 I
0 B (91) - El -’
I 0
There is no voltage between ECU terminals B (Bl) and El.
(IG S/W ON)
I
t
,
I
I 0
Check that there is voltage between ECU terminal B (Bl) and
body ground. (IG
S/W ON)
I
NO OK
Check wiring between ECU terminal El and body
ground.
Try another ECU.
I 1 Replace‘or repair. ]
Check fuse, fusible link and wiring BAD
harness. * Repair or replace.
I
1 OK
Check EFI main relay.
(See page FI-1 12) BAD
w Replace.
I OK
- El trouble
I

EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS)
FI-63
No. 1 Terminals 1 Trouble 1
Condition S-m Vnlttlnq --- ‘-‘-P-~
IDL
- E2 Throttle valve open
10 - 14 v
vcc - E2
2
No voltage Ignition 4-6V
switch ON
VTA - E2 Throttle valve fully closed 0.1 - l.OV
Throttle valve fully open
4-!iv
ECU .s
r
Fl136
I . IDL - E2
ECU
I ECU
I Y ,
F12767
0 There is no voltage between ECU terminals IDL and E2.
(IO S/W ON) (Throttle valve open)
I
1
0 Check that there is voltage between ECU terminal B (Bl) and
body ground.
(IO S/W ON)
NO
OK
, 1
I I Check wiring between ECU terminal El and body
I
1 ground.
OK
Try another ECU. 1
BAD
I Repair or replace.
I i
t
Refer to No. 1. BAD
(See page FI-62) p Replace or repair.
t
OK
, t
I@ Check throttle position sensor, ]
BAD
BAD
OK
*
Replace or repair Check wiring between ECU and
throttle position sensor. throttle position sensor.
1
OK
Try another ECU.
‘!
t

FI-64 EFI SYSTEM - Troubleshooting with Volt/Ohmmeter (MS)
Fl162
. VCC - E2 .
0
There is no voltage between ECU terminals VCC and E2.
(IO S/W ON)
1
I
Check that there is voltage between ECU terminal B (Bl) and
body ground. II0 S/W ON1
OK
7
0 Check throttle position sensor. Refer to No. 1.
(See page FL102)
(See page FL62)
k
I OK
,
1 Repair or replace.‘ / Check wiring between ECU and throttle position sensor.
OK
t I , 1 BAD ,
1 Rwe;ix3;.or replace ]
Try another ECU.
l VTA - E2
I- I
0 There is no specified voltage at ECU terminals VTA and E2.
(IG S/W ON)
I
0 Check that there is voltage between ECU terminal VCC and E2.
(IO S/W ON)
I 1
I OK
I
[@ Check thrc1 BAD 4 Repair or replace. 1
I
1 OK I ‘1 4 Check wiring between ECU and
throttle position sensor.
I
1 OK BAD
- Repair or replace.
1 Try another ECU.
1
I

EFJ SYSTEM - Troubleshooting with Volt/Ohmmeter (MS) FI-65
-_
No.
Tprminals Trouble Condition ._
STD Voltage
vcc
- E2
4-6V
Ignition
vs
- E2
SIW ON Measuring plate fully closed
4-6V
3 vs - E2 No voltage Measuring plate fully open
0.02 - 0.08 V
vs
- E2 Idling
2-4V
vs
- E2 3,000 rpm
0.3 - 1.0 v
0 ^,
-’ E2
r; wt.
I ’
I Air Flow Meter Air Flow Meter
# #
I- I-
= =
ECU
Air Flow Meter
I
FIl28:
I
I
I
ECU
El
Fl126!
0 There is no voltage between ECU terminals VCC or VS and E2.
(IG S/W ON)
1
0 Check that there is voltage between ECU terminal B @I) and
body ground. (IG S/W ON)
c
OK
NO
7
Refer to No. 1.
(See page FI-62)
7
Check wiring between ECU terminal El and body ground.
OK BAD
0 Check air flow meter.
(See page FI-96) Repair or replace.
,+, ,I, Check wiring between ECU and air
Try another ECU.

FI-66 EFI SYSTEM - Troubleshooting with VoltjOhrnmeter (MS)
-.
Ua. I
Terminals 1 Trouble 1 Condition
I STD Voltage
No. 10
EOI
4 No. 20 - ignition switch ON g-14v
No. 30 E02 No voltage
Battery i
T
ECU
IG S/W
‘No. IO ‘No. 20
‘No. 30
IEOI
I E02
c
+? &
=
FU.9
mb Fl291
0 There is no voltage between ECU terminal No. IO, No. 20
and/or No. 30 and EOl or E02. (IG S/W ON)
‘
J
0 Check that there is specified voltage between resistor
terminal +B and body ground. STD voltage: 9 - 14 V
Check wiring between
resistor and battery. BAD
-t Repair or replace.
I
Check that there is specified voltage between resistor terminal
@ (No. 10, No. 20 or No. 30) and body ground.
STD voltage: 9 - 14 V
I
e,+i Check resistance of magnetrc co11 rn
I
Check wiring between ECU and
iniector. I I Replace injector,