ECU MAZDA PROTEGE 1992 Repair Manual

22 KNOCKING
DESCRIP- *Abnormal combustion accompanied by audible “pinging” noise
I-ION
[TROUBLESHOOTING HINTS]
3 Incorrect ignition timing (Too advanced)
@ Air/Fuel mixture too lean
3 Carbon deposits in cylinder
*Fuel injection amount not correct
3 Overheating
l Fuel line pressure decreases while accelerating
TEP INSPECTION
ACTION
1 Connect System Selector to diagnosis connector
Yes Go to next step
and set Test Switch to “SELF TEST” and check
for correct ignition timing at idle after warm-up
CT page F-79
Ignition timing (BTDC)
l BP DOHC : go-1 1 o l BP SOHC : 4”-6O
’ B6 No
Adjust a page F-79
2 Check if “00” is displayed on Self-Diagnosis
Yes Go to next step
Checker with ignition switch ON
W page F-62
No
Service Code No. displayed
Check for cause (Refer to specified
check sequence) w page F-63
“88” flashes
Check ECU terminal 1F voltage CT page F-150
Specification: Battery voltage
(Ignition switch ON)
c3 If OK, replace ECU w page F-149
W: SELF TEST c3 If not OK, check wiring between
ECU and Self-Diagnosis Checker
3 Check for correct intake manifold vacuum at idle
Yes Go to next step
VaCUUm: More than 450 mmHg (17.7 inHg) No
Check for air leakage of intake air sys-
tem components
4
Check for correct engine compression
Yes Go to next step
w page Bl-10
B2-10
Engine compression (Minimum):
l BP DOHC
883 kPa (9.0 kg/cm’, 128 psi)-300 rpm
l BP SOHC
834 kPa (8.5 kg/cm*, 121 psi)300 rpm
l B6
932 kPa (9.5 kg/cm’, 135 psi)300 rpm No High compression
Check engine condition CI page 81-10
62-l 0 l Carbon deposits
F-71

F TROUBLESHOOTING GUIDE
STEP INSPECTION ACTION
5 Check for correct fuel line pressure at idle Yes Check if fuel line pressure decreases
w page F-129 when accelerating quickly
Fuel line pressure: + If it decreases, check for clogging
265-314 kPa (2.7-3.2 kg/cm’, 36-46 psi) between fuel pump and pressure
(Vacuum hose to pressure regulator dis- regulator
connected) * If not decrease, go to next step
INSTALL CLAMPS No Low pressure
Check fuel line pressure while pinching
fuel return hose
c3 If fuel line pressure quickly in-
creases, check pressure regulator w page F-129
c3 If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
If not clogged, check fuel pump
maximum pressure w page F-126
6 Check if cooling system is OK Yes Go to next step
w page E-13
No Repair or replace
l Thermostat w page E-9
l Electric cooling fan w page E-16 l Radiator w page E-6
7 Try known good ECU and check if condition Yes Replace ECU CT page F-149
improves
CT= page F-149 No
Change fuel to another brand or use
higher octane fuel
23lJOFX.0: .-._ ,
F-72

TROUBLESHOOTING GUIDE F
23 FUEL ODOR
DESCRIP-
*Gasoline odor in cabin
TION [TROUBLESHOOTING HINTS]
@ Poor connection or damaged at fuel system or evaporative emission control system
@ Charcoal canister overflow due to evaporative emission control System malfUnCtiOn
Check for cause (Refer to specified Specification: Battery voltage
(Ignltlon switch ON)
c3 If OK, replace ECU r;+ page F-149 c3 If not OK, check wiring between
ECU and Self-Diagnosis Checker
control) with engine running and throttle valve
opened (Neutral switch connector disconnected)
eck if vacuum is felt
s
23UOFX-029
F-73

TROUBLESHOOTING GUIDE F
26 POOR FUEL ECONOMY
DESCRIP-
l Fuel economy unsatisfactory TION
[TROUBLESHOOTING HINTS]
While fuel consumption is drastically increased by city driving, short-run operation, stop and go driving, extended winter
warm-up periods, etc., as opposed to “trip” mileage, an attempt should be made to determine these factors when con-
fronted with “poor mileage” conditions. However, since the operator is not always at fault, the following is offered.
@II Operator depressing accelerator more than usual due to
@ Air/Fuel mixture too rich
low engine power
l Poor ignition *High fuel line pressure
@ Alcohol blended fuel used
*Low intake air amount
l Electronic spark advance control system malfunction @ High vehicle load l Low tire pressure
*Clutch slipping/ATX slipping l Incorrect tire size l Exhaust component restricted l Brake dragging ;TEP
INSPECTION ACTION
1
Check factors other than engine Yes
Go to next step
l Low tire pressure = Section Q 9 Unrecommended tire srze v Section Q l Clutch slipping w Section H l Brake dragging No
0 Section P Repair
l Exhaust component restricted cz= page F-136
2
Check if air hoses are connected correctly - Yes
Go to next step CI page F-109
No
Repair 3
Check if “00” IS displayed on Self-Diagnosis
Yes
Checker with ignition switch ON Go to next step W page F-82 No
SYSTEM SELECT: 1 Service Code No. displayed Check for cause (Refer to specified
check sequence) w page F-63
“88” flashes
Check ECU terminal 1F voltage w page F-150
Specification: Battery voltage
(Ignition switch ON)
* If OK, replace ECU CT= page F-149 e If not OK, check wiring between
ECU and Self-Diagnosis Checker 4
Check for correct intake manifold vacuum at idle
Yes Go to next step Vacuum: More than 450 mmHg (17.7 inHg) No
Check for air leakage at intake air sys-
tem components 5
Check if air cleaner element is clean Yes
Go to next step CT= page F-79
No
Replace air cleaner element
F-75

TROUBLESHOOTING GUIDE
27 MIL ALWAYS ON
DESCRIP- *Self-Diagnosis Checker does not indicate Malfunction Code No. but MIL always ON
TION
[TROUBLESHOOTING HINTS]
*Short circuit in wiring harness
l ECU malfunction
iTEF 1
1
-
s
Disconnect (Y/B) wire from ECU and check if
MIL goes off
‘YIB
ATX YIB
INSPECTION ACTION
Yes Replace ECU CT page F-149
No Check for short circuit in wiring be-
tween instrument cluster and ECU
23UOFX-042
28
MIL NEVER ON
IESCRIP- *Self-Diagnosis Checker indicates Malfunction Code No. of input device but MIL never ON
RON *Other indicator and warning lamps OK
:TROUBLESHOOTING HINTS]
b Bulb burned
‘Open circuit in wiring harness
m ECU malfunction
TEP INSPECTION
ACTION
1 Ground (Y/B) wire at ECU with jumper wire and
Yes Check connection of ECU connector
check if MIL comes on
MTX e If OK, replace ECU w page F-149
I- i -!~ !r--~r’:~;-‘;- --~_:- ,
1 i r 1 1 1 ;-.:,~;~$~& {-;&# ,$&]j 4 If not OK, repair ECU connector
! No
Check if bulb is OK
ATX 13 If OK, repair (Y/B) wire between
ECU and instrument cluster
e If not OK, replace bulb CT page T-83
23UOFX-043
29 A/C DOES NOT WORK
DESCRIP- *Blower fan operates but magnet clutch does not operate
TION
[TROUBLESHOOTING HINTS]
*Open or short circuit in wiring harness
*A/C relay, A/C switch, or magnetic clutch malfunction
l ECU malfunction
TEP/ INSPECTION ACTION
1 1 Check ECU
terminal 10 (MTX) 10 (ATX) voltage 1
Yes Check ECU terminal 1 J (MTX) 1 L (ATX)
OK
CT= page F-152
MTX
T7J++!;i”-
L
ATX
No voltage OK
CT page F-152
1-3 If OK, check A/C system
c3- page U-30
~3 If not OK, replace ECU CT page F-149
Check for cause w page F-153
F-77

F SELF-DIAGNOSIS FUNCTION
SELF-DIAGNOSIS FUNCTION
DESCRIPTION
The engine control unit (integrated with the EC-AT control unit) has built-in Self-Diagnosis function the same
as for the previous models. When trouble occurs in the main input devices or output devices, they are indi-
cated and retrieved from the engine control unit (ECU) as service code numbers.
When inspecting for service code(s) memorized in the ECU use the Self-Diagnosis checker and system selector
(SST).
Note
l The ECU constantly checks for malfunction of the in put devices. But, the ECU checks for
malfunction of output devices only in a three second period after the ignition switch is turned
ON and the TEN terminal of the diagnosis connector is grounded.
-
-
INPUT =
SIGNALS-
-
-
- SELF-
DIAGNOSTIC
L!
I-
FUNCTION ENGINE CONTROL
UNIT
j FAIL-SAFE
FUNCTION
I
SYSTEM SELF-DIAGNOSIS
SELECTOR
CHECKER
MIL
(MALFUNCTION
INDICATOR LAMP)

F SELF-DIAGNOSIS FUNCTION
Troubleshooting
If a service code number is shown on the SST, check for the cause by using the chart related to the code
number shown.
Service code number
CODE LOCATION OF
NO.
MALFUNCTION OUTPUT SIGNAL PATTERN
SELF-DIAGNOSIS FAIL-SAFE
02
Ne-signal
:E nl-u No Ne-signal
-
03 G-signal
(DOHC) No G-signal Cancels 2-group
injection
06* Vehicle speed
sensor ON
OFF No input signal from Shifting performed
vehicle speed normally
sensor
08 Airflow meter ON
OFF Open or short circuit Basic fuel injection
amount fixed as for two
driving modes
(1) Idle switch ON
(2) Idle switch OFF
09 Water
thermosensor ON
OFF Maintains constant 20%
(68OF) command
10 Intake air
thermosensor Maintains constant 20°C
(68OF) command
12
Throttle sensor
“,E l--uL-l Throttle opening judged
as full stroke lockup not
provided
Atmospheric ON Maintains constant
14 pressure sensor command of sea level
(in ECU)
OFF pressure
15 Oxygen sensor
(inactivation) ON
OFF Sensor output
continues less than
0.55V 95 sec. after
engine starts
(1500 rpm) Cancels engine feedback
operation
Oxygen sensor ON Sensor output Cancels engine feedback
17
(Inversion) continues uncharged operatron
OFF 50 sec. after engine
exceeds 1500 rpm
Solenoid valve ON
25 (pressure
regulator)
OFF u 1 nnluln Open or short crrcurt
“If the marked code numbers appeor, refer to Section K
F-84

SELF-DIAGNOSIS FUNCTION F
:ODE LOCATION OF
NO.
MALFUNCTION
26 Solenoid valve ON
(purge control)
OFF OUTPUT SIGNAL PATTERN nnnnnll 1 SELF4IAGNOSIS
Open or
short circuit FAIL-SAFE
-
ON
34
ISC valve
OFF u 1 llllJlll r -
41 Solenoid valve ON
(WCS)
[DOHC]
OFF -
Pulse ON No input signal Shifting performed in
55*
i nnnnn
from pulse accordance with signals
generator
OFF generator from vehicle speed
sensor
Open or Solenoid valve(s)
60* 1-2 shift ON
short circuit
solenoid valve
uuuuul performs the shifting with
as little interference as
OFF
possible with driving
performance
2-3 shift ON Lockup not provided
61*
solenoid valve
OFF
UUUI n
3-4 shift ON
62’
solenoid valve
OFF u u u u inn
1.6 sec. 4 sec.
63* Lockup solenoid
valve
u u&m I- Shifting performed
normally
Lockup not provided
0.4 sec.
0.4 sec.
*If the marked code numbers appeor, refer to Section K
Note
l The HOLD indicator does not flash the service code numbers.
l If there is more than one failure present, the code numbers will be indicated in numerical or-
der, lowest number first.
* After repairing a problem, turn the ignition switch OFF and disconnect the negative battery
cable at least 20 seconds to erase the service code numbers from the engine control unit (ECU)
memory.
23UOFX-051
F-85

F SELF-DIAGNOSIS FUNCTION
Troubleshooting
If a service code number is show on the SST, check for the cause by using the chart related to the code
number shown.
r c :ODE No. -
iTEl
I 02 (DISTRIBUTOR Ne-SIGNAL)
INSPECTION I
ACTION
1
1
2
Check if Code No.03 is also present
-5- Check terminal-wire for continuity
4
Check if battery voltage exists at distributor
terminal-wire
-i-- Check terminal-wire between distributor and
ECU terminal 2E (MTX) 2A (ATX) for continuity
and ground
6
Cl$c; ,if$CU terminal 2E (MTX) 2A (ATX) volt- Yes Replace ECU
w page F-149
w page F-152 . No
Go to next step
7
I I
Check if OV or 45V--55V exists at distributor 1 Yes 1 Reolace distributor I
8
- Check distributor circuit for poor connection Yes
1 I Repair or replace connector
I
No SOHC
Go to Step 3
DOHC
Go to next step
Yes Go to next step I
No Go to Step 5
Yes
I I Go to next step
I
No
I I
Repair or replace
Yes Go to next step
No Check for open circuit in wiring from
distributor to main relay (FUEL INJ
relay)
Yes Go to next step
No Repair or replace
terminal-wire (W)
No Go to next step
Check if 4.5V-5.5V exists at ECU terminal 2E
(MTX) 2A (ATX) (With distributor connector dis-
connected) Yes Check for short circuit in wiring from
distributor to ECU
No Replace ECU CT page F-149
.-I 4
F-86

SELF-DIAGNOSIS FUNCTlON F
I
ECU
Ne-SIGNAL
Circuit Diagram
MTX
30A MAIN RELAY
Cl IEl Ihl I ra)El A”
B/W ,, ,, B/w ,, m/W ,/ +,J@ , ““l”
\ IF \ ,,
ff W Y/L
II f
II II $4
BlLG
WIG I ___ --- -i-
((
I*
- & W/R
B
t B.
DISTRIBUTOR
ATX
r
ECU
Ne-SIGNAL
MAIN RELAY .
w-w
(FUEL INJ RELAY) w-w
WIR
23UOFX-O!
F-87