SYSTEMS
NGINEMANAGEMENT,FUEL,IGNITION& EXHAUST
but by all means use a switch cleaning lubrioa them, reconnect the wiring and check
the fault has disappeared.If so, great - you
yourself a significantparts bill. If not, at
gou will know that the fauli really is down to
U (but don't forget to check the rest of the
components - see below).
D 2 8 l I O E C UT E R M I N AILD E N T I F I C A T I O N .
ment, you can perform voltage checks at the ECU
to determine whether the ECU and related sensing
If
ffi If you happen to have access to the and control systems are operating correctly.
Signal Monitor, Adaptor and overlay sheet using the Engine Signal Monitor and Adaptor,
unplug the ECU wiring and connect the adaptor
and monitor as shown in the accompany diagram.
10
ffi ffi While we do not recommend this
course of action, if you are suitably skilled in this
sort of work and have appropriate equipment, it
would seem reasonableto
Input )utpu funnedlon to
make each voltage check
at the terminal concerned,
o
noting that the ECU must
be connected normally
1S
o
during the test. You will
T
o
need to introduce the
meter positive (+) probe
o
through the back of the
wiring connector, so a
swilch (MT)
o
D28/9ECUVOLTAGE
CHECKS.
finetipped probe will be
lnhrbtor s[ch
{AT)
needed, and care must be
earlier,or are skilledin electronicdiag- taken to avoid damage to 2 8
and have suitable alternativd test equip- i h e t e r m i n a l p i n s . T h e
VOLTAGE
CHECKS
ECUTERMINAL
2E
2l
meter negative (-) probe should be connected to a
suitableground point. The terminal locations are as
shown in the diagram.
11
ffi If the readings obtained at one or more
terminals are not as shown in the above table,
make a note of the reading found and refer to the
table for details of abnormal readings and sugqested causes.
o
Crank angle
sensor (N€.sianal)
o
Crank angle
*nsor (G-sional)
Ground (Fderal)
o
rgnter
Rear window deto$er
switch OFF
Rear window ddrder
swilch ON
illuminated lor 3 w.
affer ignilion
haild
lgnilion siEh
ON
B6low 1.0V
lgnilion swilch
ON
Headlights ON Oail, parkng, low boam/
Headhohis OFF
NeuilaL rcsfion d clurcn pmal
N Or ts ranoa
Con$ant
Conslanl
ldle
2K
Lmp
Voltrg.
Tcat condlllon
Fan operatng (Engno cmlanl lemFra'
lure over 97oC l207"Fl or dragnosis
connmtor lsrmind TFA qrounded)
Fan not ooeralno 0dle)
Blower conlol swtci at mro, hrgh or
5-
:on$anl
2L
o
2M
o
(Ar)
2N
o
Oxygen sensor
Acceleralor Fdd releasd
Acc8terarct oeoar ruilv
lrcreaso engine spe€d (Aner werm-up)
o.5-1V
Ded€€uon
Buzer soundlor 3 s€. afrerignrtion
swllchOFF*ON
. With SelfDiagnoss
Ch@kefand
Syst€mSelstor
. With Sy6tem
S€l6tor te$
20
o
2P
o
20
o
Approx.2.5V
At 200c tsoFl
bufi tn
lh6tmosn$r
T28/IOSECUTERMINAT
VOLTAGETEST
TABLE.
.,SELF-TEST''
l|.ff
ttrgarl OdF
coimtlonb
I
rdoidnlon
Yotraga
Ramd(
:
IH
| lgmm
I ldle
swrch oN
o
hidxor N6. 1, 3
Ged€ral and
Csed.)
No.r (C8litohhl
ll
o
Iniexd N@. 2, 4
(F€ddal and
Cffi&)
No.z (Calildnb)
N
o
ISC vdw
o
Sddid
vdw
(Purg6 @ffid)
tot6
o
Inlffi
No. 3
(Cditdnb)
@d€ra[on
2U
2X
TffiffiffidJOm
I rth rafrer,'.mn,6r
r
to t,rOO
Approx.r2V
td6
3,ru rmb
rftrdonrd
l,w
' Engi@
Signal
Monbr: Gr€n
and red lighb
ll*h
'
Engine Signal
Monior: Grsn
d
rd lights
llash
pprox./v
'
2Y
rom J,@
rpm @ t,s
'
z
TABLE.
T28lIOA ECUTERMINAL
VOTTAGETEST
Inldd
No. 4
{Cdfrdnie)
lEasatron
(Feddal
lgnilion swibh ON
o
and
rm
!,@
m
o r,s
Engine Signal
Monior: Grsn
and €d lighls
lla$
Engino Signal
Monilofr Gren
and rd lighb
fld
T28lIOC.ECUTERMINAL
VOTTAGETEST
TABLE,
5:37
MAZDAMTATA/MXs
lmld
C@ndlon
lo
Abnomd
vohga
Batery
(Batery OK)
1E
PolbL 6us
. BmM 10Afus burned
. Opsncicuit in wfing liom ROOMjoA tus to ECU
termindI A
Coodlo
Ndfd
Cldch
to
Abnomd
vollga
swtoh
silch (MT)
. Marn r€ley malfurction
. Open ckcuil in Wr ng tom main retay to ECU
teiminal 18
lc
(Sbd Silion)
. oFn crcul 1n wring from stat€r inlerltrk
ECU leminel lC
(Sbder tums)
1D
Ch*ke.
Poor conndion at ECU conn&tor
. Inhiblor switch malluncton
hhibitor switch (AT)
. Shod cfcuil ln wiing lrom inhibitor switch to ECU
. P@r conn€tion at ECU conn*tor
. ECU mallunction
. lnhrb{or swilch maltunction
. ECUmallurction
Mdlurcton indcalor
lamp (MlL)
(MlL always ON)
(MlL never ON)
. Open c?cuit in wirng from inhibitor switch to ECU
. Sho4 ctcuil 1 wting irom combinalon met€r ro
ECU leminal lE
. ECU mdlunclion
2A
2A
2C
20
2E
. OFn cifcuit in wfing lrom combination meter to
ECU terminal lE
Poor connetion at Ecu connetor
ECU malfunction
SdiDiagncis
(Cde No.)
Chek€r
(No display on SeliDiagncis
Ch*ked
("88" b displayed and
buzer sounds continuously)
Gfound
Crank angle snsl
(Nesignal)
2G
Main relay mallunction
OFn cfcuil n wting from maln relay to diagnoss
connetor lerminal +B
2l
. open o. sho( cicuit in wirlng lrom dlagnosis
connetor terminal FEN lo ECU t€rminal 1F
(!C
d@s nol oFrale)
switch OFF bul lJC
. Reler to Code No.02 houbleshooting
Shod ckcuii in wfing iiom ECU terminat 2K to atrPoor conn6tion al ECU connstor
ECU mallunction
Thrdle sn$r
(Powef l6ninal)
Poor connetion al ECU conn@tor
ECU malfunclion
tuo relay mafunction
Open cifcut in wfing from main relay to NC retay
Opn cifcuil in wklng ftom AC relay lo ECU term.
nd 1J
. Shon ckcuit in wiring lfom ilC retay to ECU term nd
]J
. ECU mallunclon
1M
DaagnosisconMtor
{Temnal TEN)
Vehicle sFd
(Calilomie)
snsr
Always approx. 7V ;
I hrof,le sensor misadjudment
OFn cfcuil in wking lrom ECU lermtnat 2L to throt
Open c rcuit in wfing lrom thronte $nsor to ground
2M
Thrdle sn&r (AT)
Open ctcuit in wfing from ECU lerminal 2M lo throt
Open cicuit in wlr ng tom ECU terminat 2K lo nfor
OFn
. Shod crcuit in wklng lrom ECU lerminat 1K to diag
nosis conn@tor lerminal TEN
. OFn c rcuil in wiing from ECU teminat 1K to diag.
nosis conn*lor termnal TEN
. Open c fcult in wi ng liom diagnosis connetor ler
m nal OND to ground
2N
. Vehicle speed sonsor malllncuon
. Shon ckcuit in wflng trom vehicle speed sensor to
ECU lerminal lM
20
. Vehcl€ speed snsor malfunction
. OFn clcut in wiing liom vehcle sped
ECU lemlnel lM
*nsf
1N
Ahoftd
vonrgc
Thrd6 snsr
(ldle ltrmind)
Poslblc
ctrcuil n wtring lrom ECU lerm nat 2D to thro!
Thronle s€n$r misadiuslmeni
Oxygen snmr
. Reier to Code No.15 toubteshooting
. Beter to code No,17 toubleshooting
2P
Always ov or approl
Aidlow mda
(tntake a[
5v
Always0V or approx.5V
. Roier to Code No.08 rolbLeshool ng
. Beter to Code No.10 toublesh@ting
to
. lntake a r lhermosensor malilnclon
128/11A ECUTERMINALVOTTAGETEST- ABNORMALREADINGCHECKLIST.
ConMhb
. ECU mallunction
Thronle sener mallundion
Shod cicuit n wking hom ECIJ rehtnal 2L to thro!
(MT)
ffC switch mallunction
Poor connetion at ECU connslol
ECU mallunction
1K
. Bsler to Code No m roubteshootng
. Reler lo Code No.01 toubleshootng
Below4.5Vor above5.5V
. ECUmdturcton
(ilC
AlwaF 0V or approx.5V
lgnil€r
Feler lo Code No.01 troubloshmUng
IJ
. Poor codact at ground terminal
. Op€n cfcuil in wfing from ECU to gfound
2r
IH
(Calilornia AT)
More than 0V
AlwaF 0V or approx.5V
. P@r connetion al ECU conn€tor
. ECU mallunciion
lgntef
ous
Neutral swdch mallunction
Clulch swilch mallunction
Open clrcull in wfing fiom ECU leminal 1V to neu-
switch to
Man relay malfunclion
Open cfcun in wiing hom main retay lo diagnGis
connetor lBrmrnal +B
OFn of shon ctcuil n wking irom diagnosis
conn4tor termlnd MEN to ECU terminat iD
(Monitor lamp)
Po$lbh
Neuf al switch malfunction
Clutch switch matlunclion
Shod cfcuit in wi ng from ECU teminat 1V to n6u.
ECUTERMINALVOTTAGETEST- ABNORMATREADINECHECKLIST.
128/IlC
eue
fhronle snsr
msdiuslmeni
Shon cicuit in wiing trom ECU terminat lN to tnrd.
rffi
20
Condlon
b
wd6r lhemNnsr
Abno.mrl
volt.ge
Always0V or approx.5V
P@lbl.
. Reler ro Cde
6us
No 09 [oubleshooling
ECU malfunction
. Watsr thermosensor malfunciion
. Thrcne snsor migdju$ment
.
. OFn ckcuil in wtring hom ECU teminat tN
to throt
10
$oplighl
swilch
(stopliqhts
oK)
. Open circlit in wting irom throfre sensr
to ground
open c-cul in wil ng tiom stopt.gnl swlch ro Ecu
terminal 10
Injelor
. Main relay mdunction
2V
. Ooen o. shod c{cut In wnng kolsrmrnal 2U or 2V
. ECU malfunction
P/S pre$ure swibh matlundion
ISC valve
Injeror to ECU
. Herer to code No.34 toubtshoolino
Shod crcuil in wring irom ECU leminal 1p to p/S
ECU malfunction
P/S presur€ swilch mallunction
2X
&lenoid valve
(Purg6 conroD
Refer to Code No.26 foubtshooling
Open circult in w I ng trom ECU teminat 1p to p/S
Open ctcuil in wting tiom p/S pressure swltch to
9rouno
1Q
(wilh blorer
switch ON)
AC swlch mallunction
Open cfcuil n wning from ECU tehinat
Ooen c'cul
IR
(C@ling lan OK)
IS
Blower codfol switch
{Abwer lan OK)
{Blow€r fan OK)
IT
Fear window ddro*er
switch {Calilornia)
lllumlnallon lamp
ON when rear
1.0v
in w" ng from AC sw{ch lo btower con.
. Ooen o. sfod^c.cul
I wnng tor
lan reley lo ECU lermrnal 1R
. ECU mallunction
Siol
ECU
Poor
ECU
dsrc
lnj@tor (Calilornia)
. Main relsy malllnclion
. Ooen o. shon c'cu{ In wtrnq lom
lerminal 22
nidor
to LCU
. ECU mallunclon
{Federal and Canada)
c@hng
cicuir In wtrng tiom b'ower conpot switch to
termrnal 15
connslion al ECU conntrtor
malfunction
. 9pen crcuil n winng trom blower contot
switch lo
ECU terminal 15
. OFn or shon cicut in wUng lrom reaf window
derosler swilch lo ECU leminal 1T
. Open cfcuil n wking trom gniton
switch to rear
wndow detroster swltch
. Rear wlndow deffosler swlch malfunc|on
H€adlight
(Headliohls OK)
128/IIB ECUTERMINALVOTTAGETESI- ABNORMALREADINGCHECKLIST.
5:38
. Main relay maltunclion
. Ooen or-shod c-cu{ ,1 wmng I'om ,nj4tor
lo ECU
le to AC
swtch ON
llluminallon lamp
never oN
Injeror (Catifornia)
ilC swilch maltunction
Shon cfcuit in w rng irom ECU teminat tO to AC
Poor connelion at ECU connstor
ECU malfunclion
(with blower switch ON)
(Blower ian OK)
. Solerord valve (Purge @ntot) maluncnon
128/IID ECUTERMINALVOTTAGETEST. ABNORMALREADINGCHECKLIST.
w 7tI,2.
1
11 The crank angle sensoris located at the
back of the cambox cover. Note that it is adjustable
- its position sets the ignition iiming so apply a
paint mark between the slotted adjuster and the
adjacentcasting,so you can refit it without affectinq
the timinq.