1992 MAZDA PROTEGE ECU

SELF-DIAGNOSIS FUNCTION F
Circuit
MTX
OXYGEN SENSOR
ECU
23UOFX-07
ATX
OXYGEN SENSOR
R/L
-em---- ----- -- ECU
WLG
23UOFX-072
F-99

SELF-DIAGNOSIS FUNCTION
:ODE No. 17 (Oxygen sensor-lnvarsion)
r t
INSPECTION
Check if same Code No. is present after per-
forming after-repair procedure CT- page F-704
Check monitor lamp of Self-Diagnosis Checker il-
luminate at idle after warming-up engine and
running it at 2,500-3,000 rpm
for 3 minutes
Check for correct fuel line pressure at idle CT page F-129
Fuel line pressure;
265-314 kPa (2.7-3.2 kg/cm2, 38-46 psi)
{Vacuum hose to pressure regulator
disconnected)
4 Check injectors for fuel teakage c3 page F-132
5
Disconnect each high-tension lead at idle and
check if engine speed decreases equally at each
cylinder
Circuit Oiagram
MTX
I ACTION
Yes 1 Go to next step NO
Check oxygen sensor circuit for poor
connection
r3 If OK, perform troubleshooting
Code No.15
a
If not OK, repair or replace con-
nector u page F-98
Yes Go to next step Note
l A/F mixture rich
No
I Go to Step 5 Note
l A/F mixture is lean or misfire
occurring
Yes
I Go to next step No High pressure
Check if fuel return hose is ciogged or
restricted
+ If OK, replace pressure regulator CT page F-130
c3 If not OK, repair or replace
Yes Replace injector
No Check if water thermosensor is OK
ti if OK, Go to Step 11
c3 If not OK, replace water thermo-
sensor c7 page F-168
CT page F-168
Yes
Go to next step No
Go to Step 8
23UOFX-07
OXYGEN SENSOR
I
R/L
ECU
----------h--M
23UOFX-074
F-l 00

SELF-DIAGNOSIS FUNCTION F
TEP
6
7
8
9
IO
11 INSPECTION
Check for correct fuel line pressure at idle
IV page F-122
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm’, 38-46 psi)
(Vacuum hose to pressure regulator
disconnected)
Check intake air system components for air
leakage
Check for misfire of dead cylinder from Step 5
inspection
Check for injector operating sound at idle of
dead cylinder from Step 5 inspection -
Replace injector at dead cylinder from Step 5 in-
spection
CI page F-131
Check if same Code No. is present following
performing after-repair procedure
CT page F-104
Try known good ECU and check if condition
Improves
CT page F-149 Yes
No
Yes If not clogged, check fuel pump
maximum pressure
Go to Step 11
No Replace
--
Yes Repair or replace ignition system
No
Yes
No
Yes
No
T L ACTION
Go to next step
Low pressure
Check fuel line pressure while pinching
fuel return hose
~3 If fuel line pressure quickly in-
creases, check pressure regulator
v page F-129
c3 If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
CT page F-126
Go to next step
Go to next step
Check for battery voltage at injector
connector terminal-wire (W/R)
L3 If Yes, replace injector c7 page F-131
+ If No, check wire harness for short
or open
Go to next step
Removed injector at fault
Circuit Diagram
ATX
OXYGENSENSOR
R/L
ECU
-------------- ---
BILG
23UOFX-07
F-10'

SELF-DIAGNOSIS FUNCTION
:ODE No. 1 25 (SOLENOID VALVE - PRESSUREREGULATORCONTROL)-BPENGINE
r (
TEP
1
-
2
-
3 I
INSPECTION
Disconnect connector from ECU and check if
battery voltage exists at ECU terminal 2T (MTX)
3M (ATX) wire (G/O) with ignition switch ON
In same condition as Step 1, check if battery
voltage exists at solenoid valve connector
terminal-wire (G/O) ACTION
Yes Check ECU terminal connector for poor -
connection
* If OK, replace ECU CT page F-149
+
If not OK, repair or replace connector
No Go to next step
Yes Repair or replace wire (G/O)
No Go to next step
Check if solenoid valve is OK Yes Check for short or open circuit in wiring
w page F-135 from main relay (FUEL INJ relay) to
solenoid valve
No Replace solenoid valve
I I I
23UOFX-077
:ODE No. 26 (SOLENOID VALVE - PURGE CONTROL)
STEP INSPECTION
Disconnect connector from ECU and check if
battery voltage exists at ECU terminal 2X (MTX)
20 (ATX) wire harness (W/L) with ignition switch
ON Yes
No
In same condition as Step 1, check if battery
Yes
voltage exists at solenoid valve connector
terminal-wire (W/L)
No
Check if solenoid valve is OK
Yes
w page F-140
t- No
--
4 ACTION
Check ECU terminal connector for poor
connection
ti If OK, replace ECU c;p page F-149
e
If not OK, repair or replace connector
Go to next step
Repair or replace wire harness (W/L)
Go to next step
Check for short or open circuit in wiring
from main relay (FUEL INJ relay) to
Circuit Diagram
MTX
I-
FROM
BATTERY
FROM
23UOFX-07 9
F-l 02

SELF-DIAGNOSIS FUNCTION F
1
CODE No. 34 (ISC VALVE)
1 ACTION
Yes Check ECU terminal connector for poor
connection INSPECTION
Disconnect connector from ECU and check if
battery voltage exists at ECU terminal 2W (MTX)
3Q (ATX) wire (L/O) with ignition switch ON
c3 If OK, replace ECU
+ If not OK, repair or replace con-
nector w page F-149
No Go to next step
In same condition as Step 1, check if battery
voltage exists at ISC valve connector terminal.
wire (L/O) Yes ) Repair or replace wire (L/O)
No Go to next step
Yes Check for short or open circuit in wiring
from main relay (FUEL INJ relay) to ISC
valve
No Replace ISC valve Check ISC valve for correct resistance
w page F-i 16
Resistance: 1 l-130 [at 20°C(68”F) ]
I 23UOFX-08( I
r C :ODE No. )
41 (SOLENOID VALVE - VICSbDOHC
I
ii
T
I
INSPECTION
ACTION
Check ECU terminal connector for poor
connection
in’
I
* If OK, replace ECU w page F-149
c3 If not OK, repair or replace con-
nector
No Go to next step Disconnect connector from ECU and check if
battery voltage exists at ECU
terminal 2S (MTX)
31 (ATX) wire (B/R) with ignition switch ON
2 In same condition as Step 1, check if battery voltage exists at solenoid valve connector
terminal-wire (B/R)
Check if solenoid valve is OK
w page F-l 18 Yes Repair or replace wire (B/R)
No Go to next step
Yes Check for short or open circuit in wiring
from main relay to solenoid valve
No
Replace solenoid valve
23UOFX-081 3
Circuit Diagram
ATX
ISC VALVE
FROM
BATTERY 4
FROM
L
IGNITION d++n.D,,
SWITCH
MAIN RELAY
(FUEL INJ RELAY) S
4\ ECU
SOLENOID VALVE
i(VICS) [DOHC]
W/R ,,
\
SOLENOID VALVE ,
(PURGE CONTROL)
23UOFX-082
F-i 03

SELF-DIAGNOSIS FUNCTION F
SWITCH MONITOR FUNCTION
Individual switches can be inspected by the SST (Self-Diagnosis checker).
Note
l The TEN terminal of the diagnosis connector must be grounded and the ignition switch ON
(engine stopped).
l If either of the switches remain activated, the monitor lamp will be illuminated.
ECU
NEUTRAL SWITCH (MTX)
CLUTCH SWITCH (MTX)
=d-’ 1
BATTERY
INHIBITOR SWITCH (ATX)
STOPLIGHT SWITCH (MTX)
HEADLIGHT SWITCH MONITER LAMP
REAR WINDOW (SELF-DIAGNOSIS CHECKER)
DEFROSTER SWITCH
AIC SWITCH
BLOWER SWITCH
THROTTLE SENSOR asp-
- _
COOLING FAN SWITCH
03UOFX
Switch
Clutch switch
Neutral switch (MW
(M-W Self-Diagnosis Checker (Monitor lamp)
Light ON Light OFF Pedal released Pedal depressed
In gear Neutral Remark In gear
Clutch pedal released
Inhibitor switch
(ATX) L, S, D or R range
N or P range -
Throttle sensor Pedal depressed (Not fully) Pedal released/fully depressed -
Stoplight switch
Pedal depressed Pedal released -
Headlight switch
ON
OFF Headlights/parking lights: ON
Blower switch
ON
OFF Blower switch at 2nd or
above position
AIC switch
ON OFF Fan speed control at 1st po-
sition
Rear window defroster
switch ON
OFF -
Water thermoswitch Fan operating Fan not operating -
23UOFX-084
F-l 05

SELF-DIAGNOSIS FUNCTION
Inspection Procedure
1. Connect the SST (System Selector) to the diagnosis con-
nector.
2. Set the switch @ to position 1.
3. Set TEST SW to SELF-TEST.
03UOFX.090
MONITOR LAMP
T
03UOFX-091
Procedure
4. Connect the SST (Self-Diagnosis Checker) to the System
Selector and a ground.
5. Set the select switch of the Self-Diagnosis Checker to posi-
tion A.
6. Turn the ignition switch ON.
7. Check if Monitor Lamp illuminates when each switch is made
to function as described below.
Caution
* If either of the switches remain activated, the mon-
itor lamp will be illuminated.
l Do not start the engine.
I
I Set conditions to deactivate each switch l All accessories OFF l Transaxle in neutral l All pedals released NO
-
Verify that monitor lamp does not illuminate
YES
Check each switch as described Check each switch and related wire harness
*Clutch and Neutral CT- pages F-l 72,173
switch
*Throttle sensor w page F-169 l Stoplight switch c7 Section T l Headlight switch c7 Section T l Rear defroster switch T;P Section T l Blower switch [r+ Section T
l Inhibitor switch a Section K l A/C switch 0 Section U l Water thermoswitch c7 Section E
23UOFX-OS!
Neutral and Clutch switch (MTX)
Shift transaxle into gear
Check that monitor lamp illuminates with clutch pedal
released
YES NO PC: l Neutral switch malfunction a page F-173 l Clutch switch malfunction w page F-172
*Open circuit in related wire
harness
l ECU terminal 1 V voltage
incorrect w page F-152
l ECU malfunction
Depress clutch pedal
Check that monitor lamp does not illuminate
Return transmission to neutral PC:
*Clutch switch malfunction w page F-172
23UOFX-088
F-l 06

SELF-DIAGNOSIS FUNCTION
Headlight switch
Turn headlight switch ON
Check that monitor lamp illuminates
YES
Headlight switch OK
Turn headlight switch OFF NO
PC: l Headlight switch malfunction v Section T
*Open circuit in wire harness
from headlight switch to ECU
l ECU terminal 1 U (MTX) 1 H
(ATX) voltage incorrect CT page F-152
l ECU malfunction
23UOFX-087
Rear window defroster switch
Turn rear window defroster switch ON
Check that monitor lamp illuminates
YES
Rear defroster switch OK
Turn rear window defroster switch OFF NO
_ PC: *Rear window defroster switch
malfunction c7 Section T
*Open circuit in wire harness
from rear window defroster
switch to ECU
l ECU terminal 1 T (MTX) 1 J (ATX)
voltage incorrect
u page F-152
l ECU malfunction
23UOFX-088
Inhibitor switch (ATX)
Shift transaxle into L, S, D, or P range
Check that monitor lamp illuminates
YES
Inhibitor switch OK
Shift into P or N range PC: l Inhibitor switch malfunction
*Open or short circuit in related
23UOFX-089
F-l 07