Mil Always On - Mazda MX-5 1990 Workshop Manual

F
TROUBLESHOOTING GUIDE
I
32
MIL ALWAYS ON
DESCRIP-1- Self-Diagnosis Checker does not indicate Malfunction Code No. but MIL always ON
TION
~-.
[TROUBLESHOOTING HINTS]
- Short circuit in wiring harness
- ECU malfunction
STEP INSPECTION ACTION
1 Disconnect (Y/8) wire from ECU and check
If
Yes Replace ECU
c::r
page F-127
MIL goes off
~
No Check for short circuit in wiring be-
If
I I I
'I 1
0
1 1 i l l 1 1
~~
1 I 1 . .
I
tween combination meter and ECU
L7'
page F-9
05UOFX-049
33
MIL NEVER ON
DESCRIP-
I
-Self-Diagnosis Checker indicates Malfunction code No. of input device but MIL never ON
TION - Other indicator and warning lamps OK
[TROUBLESHOOTING HINTS]
• Bulb burned out
• Open circuit in wiring harness
- ECU malfunction
STEP INSPECTION
ACTION
1
Ground (Y/B) wire at ECU with jumper wire and
Yes Check connection condition of ECU
check if MIL comes on
connector c::r
page
F-129
c? If OK, replace ECU c:r page F-127
c:> If not OK, repair ECU connector
L7
page F-127
VIS
IR=FF I I ' I I II I I
Il~
I I I
Ff' F F
1II1
III
No Check if bulb is OK
¢
If OK, repair (V/8) wire between
ECU and combination meter
c::r
page F-8
c?
If not OK, replace bulb
c::?
page
T -33
05UOFX-050
-.
F-72