Suzuki 2000 Grand Vitara SQ625 Service Manual page 108

6-104 ENGINE DIAGNOSIS (G16 / J20 ENGINES)
STEP
4 Was idle speed within specification in
Step 1?
5 Was idle speed higher than specification
in Step 1?
6 Check A/C (input) signal circuit referring to
Step 1 of Table B-5 A/C Signal Circuit
Check, if equipped. (A/C signal can be also
checked by using Tech-1.)
Is it in good condition?
7 Check ABS signal circuit for voltage
if equipped.
1) Turn ignition switch ON.
2) Check voltage between E61-30 terminal
of ECM (PCM) connector connected and
body ground.
Is voltage 10 – 14 V?
8 Was IAC duty less than about 2% in Step 1
of this table?
9 Check transmission range switch signal
referring to "Inspection of ECM (PCM)
and its Circuit" in this section.
Is check result satisfactory?
10 Was IAC duty more than about 30% in
Step 1 of this table?
ACTION YES
Check for following:
– Vacuum leaks
– Air inhaling
– EVAP canister purge
control system
– Accessory engine load
– Stuck of PCV valve
– Clog of idle air passage
– MAF sensor
– TP sensor
– ECT sensor
– EGR valve malfunction
(leakage from valve seat)
– A/C signal
– Transmission range switch
signal
Go to Step 6.
Go to Step 7.
Go to step 8.
Check abnormal air inhaling
from intake manifold, throttle
body, PCV valve and EVAP
canister purge control system.
Go to Step 10.
Check parts or system which
can cause engine low idle.
– Air inhaling from between
throttle body and MAF
sensor.
– EGR valve malfunction
(leakage from valve seat)
– Accessory engine load
– Clog of idle air passage
– Etc.
NO
Go to Step 5.
Go to Step 9.
A/ C signal circuit open
or short, or A / C system
malfunction.
ABS signal circuit
shorted to ground
or ABS malfunction.
Check TP sensor
(closed throttle posi-
tion) and ECT sensor
for performance.
If sensors are OK,
substitute a known-
good ECM (PCM) and
recheck.
Transmission range
switch malfunction or
its circuits open or
short.
Substitute a known-
good ECM (PCM) and
recheck.