SERVICE MANUAL NUMBER 24
DIAGNOSTICS
Chart A-8 (2 of 2): Idle Air Control (IAC) Functional Test
Step
Action
Yes
No
PROCEED TO
Was the “On-Board Diagnostic” (OBD) System Check
Performed?
1.
Step 2.
OBD
a. Engine should be at normal operating temperature.
b. Start engine and allow idle to stabilize.
c. Record rpm.
d. Ignition OFF for 10 seconds.
2.
Step 3. Step 4.
e. Disconnect IAC harness connector.
f.
Restart engine and record rpm.
Is rpm Higher Than The First Recorded rpm By More
Than 200 rpm?
a. Reinstall IAC harness connector.
b. Idle speed should gradually return within 75 rpm of the
original recorded rpm within 30 seconds.
3.
4.
Step 5. Step 4.
Does rpm Return To Original Recorded rpm?
a. Ignition OFF for 10 seconds.
b. Disconnect IAC harness connector.
c. Restart engine.
Step 7. Step 6.
d. Using a test light connected to ground, probe each one
of the four IAC harness terminals.
Does The Test Light Blink On All Four Terminals?
5.
6.
IAC circuit is functioning properly.
–
Locate and repair poor connection, open, or short to ground
in the IAC circuit that did not blink or repair faulty ECM
connections
–
Verify
Repair
Check for poor IAC connections or replace the faulty IAC
valve.
7.
Index
90-861327--1
OCTOBER 1999
Page 5G-45
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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