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Idle Speed Control System (ISC)
DTC
P0506
Idle Speed Control System (ISC) - Low RPM
P0507
Idle Speed Control System (ISC) - High RPM
DESCRIPTION
The intake air volume at idle is controlled by opening or closing the idle speed control
valve provided in the air path that bypasses the throttle valve.
If there is a malfunction of the ISC system, the actual engine speed will not be identical
to the target engine speed. ECU checks the difference between the actual engine speed
and the target engine speed.
TROUBLESHOOTING GUIDE
DTC detection condition
Background
a. If there is a malfunction of the ISC system, the actual
engine speed will not be identical to the target engine
speed.
b. ECU checks the difference between the actual
engine speed and the target engine speed.
Check Area
a. Under the closed loop idle speed control.
Judgment Criteria
a. Actual idle speed has continued to be higher than the
target idle speed by 300 rpm or more for 10 sec.
Check Area
a. During idling speed closed-loop control
b. The maximum atmospheric temperature is 45°C
(113°F) or less at the last drive.
c. Long term fuel trim is at -8% to +8%.
d. Engine coolant temperature is approx. 80°C (176°F)
or more.
e. Battery voltage is 10V or more.
f. Intake air temperature is -10°C (14°F) or more.
Judgment Criteria
Diagnostic item
a. Idle speed control motor
failed
b. Open or shorted idle
speed control motor
circuit, or loose connector
c. ECU failed
Probable cause
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