Mazda MX-5 1990 Workshop Manual page 181

I ,
TROUBLESHOOTING GUIDE
STEP
INSPECTION
5 Connect System Selector to diagnosis connector Yes Go to next step
and set Test Switch to "SELF TEST" when en-
gine is cold
Check if engine speed decreases as engine
warms up
6 Disconnect ISC valve connector at idle and
check if "clicking" is heard from ISC valve
7 Pinch PCV hose with pliers and check if engine
speed decreases
8 Check if ECU terminal voltages are OK
(20, 20 and 2Q)
No Check air valve
Yes Go to next step
No Check ISC valve
Yes Check PCV valve
No Go to next step
Yes Try known good ECU
ACTION
c:::J
page
F-129 No Check for cause (Refer to "Check Point
F
c::?
page
F-99
c::::7'
page F-99
CT
page F-117
c:::J
page F-127
for Each Terminal")
c::?
page F-132
05UOFX-028
F-37