Idle Air Control (Iac) System Check - Isuzu Trooper 1999 Workshop Manual

6E–102
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step
1 1. Ignition "OFF."
2. Connect the IAC motor analyzer J37027-A to the
IAC valve.
3. Set the parking brake.
4. Block the wheels.
5. Turn the air conditioning "OFF."
6. Idle the engine in Park (A/T) or Neutral (M/T).
7. Install the Tech 2. Display the RPM.
8. Use the IAC motor analyzer J37027-A to extend
and retract the IAC valve.
9. The engine speed should decrease and increase as
the IAC is cycled.
Does the RPM change?
2 RPM should change smoothly with each flash of the
IAC motor analyzer J 37027-A light.
Does the RPM change within the range specified?
3 Check the IAC passages.
Are the IAC passages OK?
4 Clear any obstruction from the IAC passages.
Is the action complete?
5 Replace the IAC. Refer to On-Vehicle Service, Idle Air
Control Valve.
Is the action complete?
6 1. Install the appropriate IAC node light from motor
analyzer J 37027-A into the powertrain control
module harness.
2. Cycle the IAC motor analyzer J 37027-A and
observe the noid lights.
3. Both the lights should cycle red and green, but
never "OFF," as the RPM is changed over its range.
Do the lights cycle red and green?
7 1. Use the other connector on the IAC motor analyzer
J 37027-A pigtail.
2. Check the resistance across the IAC coils.
Measure the resistance between terminal A and
terminal B.
3. Measure the resistance between terminal C and
terminal D.
Is the resistance within the specified range?
8 If the circuits did not test green and red, check the
following:
f
Faulty connector terminal contacts
f
Open circuits, including connections
f
Circuits shorted to ground or voltage
f
Faulty powertrain control module connection or
powertrain control module.
Are repairs necessary?

Idle Air Control (IAC) System Check

Action Value(s) Yes
Go to Step 2
—
700-1500
RPM Go to Step 6
— Go to Step 4
— Verify repair
— Verify repair
— Go to Step 7
Go to Step 9
40-80 ohms
— Go to Step 13
No
Go to Step 3
Go to Step 3
Go to Step 5
—
—
Go to Step 8
Go to Step 10
—