1992 MAZDA 323 ECU

TROUBLESHOOTING GUIDE
(at 20% [SS*F])
If It is, check wiring
e If OK, check distributor cap and
rotor
e If not OK, replace high-tensjon lead
12 Are spark plugs UK? Yes Is engine compresston correct? w Section 82
w Section G
. Wear and carbon burld up Engine compression: l Plug gap 1059 kPa 110.8 kgf/cm*, 352 psi I-300 rpm l Damage
4 If OK, go to next step
4 If not OK, check for cause
w Section 82
c
NO Clean, adjust
13 Check for injector leakage Yes
Replace injector
No Go to next step
14 Try known good ECU: does condition improve?
w page F3-45
----- Am.*
F3-34
~ROlJ8L Engine so:
3 Idle-sp.
T> fuel-cL

TROUBLESHOOTING GUiDE F3
15 ENGINE STALLS ON DECELERATION
IESCRIP-
l Engrne unexpectedly stops running dunng or after deceleration
[iON l Idle condition normal.
TROUBLESHOOT1NG HtNTS]
ingrne speed drops too much when releasrng accelerator
3 Idle-speed misadjustment @I Loose connector disconnected by force of deceleration
3 Fuel-cut contrd malfunction
TEP lNSPECTlON ACTION
1 1s idle condition normal? Yes Go to next step
tdle speed: 800 f 50 rpm (in neutral)
NO Adjust or perform Troubleshooting, Nos.
8-I 1 “ROUGH IDLE”
(Refer to Workshop Manual
(1203-I o-89F))
2 Is “00” displayed on Self-Diagnosis Checker Yes Go to next step
with ignition switch ON?
SYSTEM SELECT: 1 NO Service Code No. displayed
Check for cause (Refer to specified
check sequence) ET page F3-16
“88” flashes
Check ECU termrnal 1 F voltage
Voltage: Battery voltage
(ignition switch ON) r;r page F346
W:SELFTEST
e If OK, replace ECU CI page F3-3
4 If not OK, check wirtng
(ECU - Self-Diagnosis Checker)
3 Does Self-Diagnosis Checker Monitor Lamp with Yes Go to next step
lgnttlon switch UN show that switches operate
correctly?
NO Lamp not ON or OFF with specified
switch
Check for cause (Refer to specified
check sequence)
W: SEtF TEST Lamp slways ON
Check wiring between
(ECU terminal 1 D - Self-Diagnosis
Checker)
4 Are ECU ?erminal voltages OK? Yes Go to next step
(especially IV, 20, 20, ZU, 2V.
and 20) v page F346 No
Check for cause
5 Check for poor connection of foltowing parts YC?S Repair or replace
l ignrtion coil l Igniter l Olstribdor l High-tension lead
NO Go to next step l Injector. l Injector resistor l Ctrcuit-opening relay . l ECU
F3-35

F3 TROUBLESHOOTING GUIDE
STEP INSPECTION ACTlON
6 Is dashpot correctly adjusted? Yes Go to next step
c
Dashpot set speed: Approx. 3,500 rpm
No Adjust dashpot
7
Try known good ECU; does condition
Improve?
w page F3-3
13EOF3-336
16 ENGINE STALLS SUDDENLY (INTERMITTENT)
DESCRIP.
l Engine intermittently stops running
TION l Before stalling, engine conditron is OK
TROUBLESHOOTING HINTS]
@ intermittently no spark or no fuel injection caused by ve-
hlcle vibratron, acceleratton, or deceleration
l Poor connectlon in wiring harness
iTEP INSPECTION ACTfON
1 Is “00” displayed on Self-Oiagnoss Checker Yes Go to next step
with lgnltlon swrtch ON?
NO Service Code No. displayed
Check for cause (Refer to speclfled
check sequence).
Note CT page F3-16
l When checking wiring harness and
connectors, tap, move, and wiggle
suspect sensor and/or harness to
recreate problem
“88” flashes ’
Check ECU terminal IF voltage
Voltage: Battery voltage
{ignition swttch ON) w page F3-45
4 If OK, replace ECU
4 If not OK, check wiring
(ECU - Self-Diagnosis Checker)
2 Check for poor connection of foliowrng parts
Yes Reparr or replace
l lgnltfon coil l Igniter l Distributor l t-flgh-tensron lead
No Go to next step l Injector l Injector reststor l Circutt-opening relay l ECU
3 Are ECU terminal voltages OK? Yes Go to Troubleshbotrng No. 2
(especially 16, 2A, 2B, and 2C) .“CRANKS NORMALLY BUT WILL NOT
w page F3-45 START (NO COMBUSTION)”
w page F3-20
Note
. No Check for cause
l When. checking voltages, tap, move, and
wiggle harness and connector to recreate
problem
* lrlrl m-7
F3-36
7.8-l

F3 FUEL SYSTEM
t 3EoF3-344
1
FUEL SYSTEM
FUEL PUMP
inspection
Fuel pump operation
1. Connect the diagnosis connector F/P and GND terminals
by using a jumper wire.
2. Remove the fuel filler cap.
3. Turn ON the ignition switch.
4.
Listen at the filler inlet for the operational sou.nd of the fuel
pump.
5. Install the fuel filler cap.
6. If no sound is heard, measure the voltage between the fuel
pump connector (G/R) to a ground.
Voltage: 8attey vo kage
7. If not as specified, check the circuit opening relay and circuit.
8. ff as specified, check fur continuity between fuel pump con-
nector (G/R) and (B).
9. If there is continuity, reptace the fuel pump.
10. If there is no continuity, repair the ground circuit.
f3EOF3.345
13EOF3-346 FUEL PUMP RESlSTORlRELAY
System Operation
1. Remove the rear seat cushion.
2. Measure the voltage at the fuel pump connector terminal
A (G/R).
Voltage
I
Cranking
1 Battery voltage
Ignition switch ON ov 3. If not as specified, perform the following inspections, and
repair or replace as necessary.
l Fuel pump resistor/relay resistance
(Refer to page F3-41.)
l ECU 11 terminal voltage (Refer to page F3-45.)
l Wiring harness and connector
F3-40
ii e -
*
_~ --
C --
A-'

-,
-,
--
--
-1
E
7
2
I
i 3EAR SE
--

F3 FUEL SYSTEM
13EOt=3-349
f3EOF3-350
0
0
ECU
G
0
0 i

13EOF3-35
tNJECTOR
t nspection
injector resistance
1. Disconnect the injector harness,
2. Measure resistance of the injector.
Resistance: l-3Q (at 20°C (68*F])
3. If
not as specified, replace the injector.
Volume Test
1, Remove the injectors and delivery pipe assembly with the
conectors con netted.
2. Affix the injectors to the delivery pipe by using wire.
Warning
l Be extremely careful when working with fuet. Al-
ways work away from sparks and open flames.
Caution
l Affix the injectors firmly to the detivery pipe so that
they do not move.
3. Turn the ignition switch ON and ground the F/P terminal
of the diagnosis connector.
4. Test the individual injectors by following the procedure out-
lined in the chart below.
Test inpctor no.
1
2
3
4 Disconnect injector connector no. Ground ECU terminal
3 2u
4 2v
1 2U
2 2v 5. Check the injection volume by using a graduated container.
Injection v&tie:
105-151 cc [6.40-9.22 cu in)/15 sec.
6. If the injection volume is not as specified, replace the injector.
INJECTOR REStSTOR
Inspection
I. Disconnect the injector harness.
?. Measure resistance of the injector resistor.. .
tnjector
No.1
No.2
No.3
No.4 Measured terminals
Resistance
gg 6 0 (at 2U°C
16PF))
3. If not as specified, replace ihe injector resistor.
F3-42 _
13EOF3-352

CONTROL SYSTEM F3
hT==TdI ,
USE CONNECTOR A 1
L
93GOF3-787 ENGINE CONTROL UNIT (ECU)
Inspection
1. Disconnect the ECU connectors.
2. Connect the SSTs {Engine Signat Monitor and Adapter) to
the ECU as shown.
3. Place the SST (Sheet) on the Engine Signal Monitor.
4. Measure the voltage at each terminal.
(Refer to pages F3-46 to F3-53.)
5. If any ECU terminal voltage is incorrect, check the related
input or output devices and wiring. If no problem is found,
replace the ECU. (Refer to page F3-2.)
t
1 13EOF3-358
r
TERMINALS
f. -I AANDB . Caution l Never apply voltage t.o terminals A and 8 of the SST.
! :OF3-359
F3-45

,,1
CONTROL SYSTEM F3 ‘1
Va: Battew voltage
Incorrect voltage Possible cause
Always OV
l ROOM IOA fuse burned l Open circuit In wiring from ROOM 10A fuse to ECU termina! 1A
Always OV
l Main relay malfunction l Open or short circuit in wiring from main relay to ECU terminal IB
Always OV (starter turns)
l Open or short circuit in wiring from ignition switch to ECU terminal IC
Always OV
Always VB
l Maln relay (FUEL INJ relay) malfunction l Open circuit in wiring from main relay to diagnosis connector terminal +B l Open or short circuit in wiring from diagnosis connector terminal MEN to
ECU terminal 1 D
l Poor connection at ECU connector l ECU malfunction
Always approx. 5V . ECU malfunction
Always below
2.5v
Always Ve -
-
No display on Self- * Main relay (FUEL INJ relay) malfunction
Diagnosis Checker
l Open circuit in wiring from main relay to diagnosis connector terminal + B
“88” displayed and
l Open or short clrcurt in wiring from diagnosis connector terminal FEN to
buzzer sounds con- ECU terminal tF
ti nuousl y
l Poor connection at ECU connector l ECU malfunction
Always QV
l Short circuit in wiring from igniter to ECU terminal 16
Always OV or VB
l Refer to Code No.42 Troubleshooting
(Refer to 323 4-Wheel Drtve Workshop Manual (12?9-IO-89L))
Always VB
Always OV
Always below
2.5V
Atways Ve I ’
l Fuel pump resistor/relay malfunction
l Open or short circurt in wiring from ECU terminal II to fuel pump resis-
tor/relay
A/C does not operate
l A/C reiay malfunction l Open circuit in wiring from ignition switch to A/C relay l Open circuit in wiring from A/C relay to ECU terminal 1J
A/C switch
OFF but l Short circuit in wiring from AIC relay to ECU terminal 1 J
A/C operates . ECU malfunction
l Poor connection at ECU connector l ECU malfunction
Always below 1 .OV a Short circuit in wiring from diagnosis connector terminal TEN to ECU termi-
nal 1K
Always Vs
l Open circuit In wiring from diagnosis connector terminal TEN to ECU terml-
nal IK
-
-
l Open circuit in winrig from diagnosis connector terminal GND to ground’
-
I -
.
. .
-. F3-47

-. _.. . . . . . _ - ._.
-w
CONTROL SYSTEM F3
I .
-.
Ve: Battery voltaae I
Incorrect voltage
Atwafi below 1 .OV
Always VB
Always VS (foglight switch OK)
Always below 1 .OV
Always below 1 .OV
Always Vs
Always
below 23 (blower fan OK)
Always VB (blower fan OK)
Always below 1 .OV
(electric cooling fan OK) -
1-
Possible cause
l Throttle sensor mrsadjustment l Short circuit in wtrrng from throttle sensor to ECU terminal 1 N l ECU malfunction
l Throttle sensor mrsadjustment l Open circuit in wiring from throttle sensor to ECU terminal fN l Open circuit in mnng from throttle sensor to ECU terminal 20
l Foglight relay malfunctron
l Foglrght relay malfunction
l P/S pressure switch maltunctron l Short crrcurt In wrrlng from P/S pressure switch to ECU terminal 1 P l ECU malfunction
l P/S pressure switch malfunction l Open circuit in wlnng from P/S pressure switch to ECU terminal 7 P l Open circuit in wiring from P/S pressure switch to ground
l A/C switch malfunctron l Short circuit tn wiring from A/C switch to ECU terminal 1Q l Poor connection at ECU connector l ECU malfunction
l #C swatch malfunction l Open circuit in wiring from A/C switch to ECU terminal 1Q l Open circuit in wiring from A/C switch to blower control switch
l Open or short circuit in wiring from fan relay to ECU terminal 1R l ECU matfunction
Always below 1 .OV (blower fan OK}
Always Vs (btower fan OK)
Always betow illumination lamp
1 .ov ON when rear
window defroster
switch ON
Illumination lamp
never ON
Atways below 1 .OV (headttghts OK)
l Short circuit in wrrtng from blower control switch to ECU terminal IS l Poor connection at ECU connector l ECU m&function
l Open crrcuit in wrrrng from blower control switch to ECU terminal 1s
l Open or short crrcuit In wiring from rear window defroster switch to ECU
terminal t T
l Open circuit in wiring from ignitron switch to rear window defroster switch l Rear window defroster switch malfunction
l Open or short circuit in wiring from headlight relay to ECU terminal 1 U
Always below 1 .OV
l Neutral switch malfunction l Clutch switch malfunction l Short circuit in wiring from ECU terminal IV to neutral or clutch switch
Always VB
l Neutral switch malfunction l Clutch switch malfunction l Open circuit in wiring from ECU terminal 1V to neutral or clutch swdch l Poor connection at ECU connector
13FOl=3-36 .
F3-49
.:i