Isc System - Mazda 626 1989 Workshop Manual

4B

ISC SYSTEM

TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4B—10 and 11.)
Possible
^ cause
Page
Symptom
During warm up
Engine
stalls
After warm up
During warm up
Rough
idle
After warm up
High idle speed after warm up
Runs rough on deceleration
Afterbum in exhaust system
Fails emission test
4B—42
Solenoid
P/S pres­
valve (Idle
Air valve sure
speed
switch
control)
4 8 — 44
4B— 43 4B— 79
_
3
2
— 4 2
2 — 3
— 4 2
2 5 3
— — 2
2 — 3
3
2 —
System inspection
(Air valve)
1. Ground the test connector (Green, 1-pin) with a
jumper wire.
. Disconnect the ISC valve connector (Gray, 2-pin)
2
at idle while the engine is cold.
3. Note the engine speed and reconnect the con­
nector.
4. Warm up the engine to the normal operating tem­
perature and disconnect the connector again.
5 . Check that the engine speed is lower than that
when cold.
Engine control unit
Water
terminal
thermo
sensor
1L 1W
4B— 86
4 5
—
5
— 3
4
— —
3 5
—
4
— 6
3
— —
4
— —
4
' —
—
\
System
in­
spection
2 0
4B— 42
6 1
6
1
5 1
6
1
7 1
4 1
5 1
5 1
76F04B-040