Idle Air Control System Check
Wiring Diagram
1. IAC valve 4. “IG” fuse 7. “FI” fuse
2. ECM 5. Ignition switch 8. “IGN1” fuse
3. Main relay 6. Relay box 9. A/C signal and head light signal
Step Action YES NO
1) Check engine idle speed and IAC duty referring to Idle Speed / Idle Air Control (IAC) Duty Inspection:M13A with VVT .
Is idle speed within specification?
Go to Step 2.
Go to Step 4.
Is IAC duty within specification in Step 1?
Go to Step 3.
Check for the followings:
• Vacuum leak
• EVAP canister purge control system
• Clog of IAC air passage
• Accessory engine load
• Closed throttle position (TP sensor)
• Stuck of PCV valve
Is engine idle speed kept specified speed even with headlight ON?
System is in good condition.
Go to Step 6.
Was idle speed higher than specification in Step 1?
Go to Step 5.
Go to Step 6.
A/C signal circuit check
1) Check A/C signal circuit referring to Step 2 of A/C System Circuits Check:M13A with VVT .
Is it in good condition?
Go to Step 6.
Repair or replace A/C signal circuit or A/C system.
Do you have SUZUKI scan tool?
Go to Step 7.
Go to Step 8.
Idle air control system check
1) Connect SUZUKI scan tool to DLC with ignition switch OFF, set parking brake and block drive wheels.
2) Warm up engine to normal operating temperature.
3) Clear DTC and select “MISC TEST” mode on SUZUKI scan tool.
Is it possible to control (increase and reduce) engine idle speed by using SUZUKI scan tool?
Go to Step 9.
Go to Step 10.
Idle air control system check
1) Remove IAC valve from throttle body referring to Idle Air Control (IAC) Valve Removal and Installation:M13A .
2) Check IAC valve for operation referring to Idle Air Control (IAC) Valve On-Vehicle Inspection:M13A .
Is check result satisfactory?
Go to Step 9.
Go to Step 10.
Was IAC duty less than about 3% (or more than about 97% for OFF duty meter) in Step 1 of this table?
Check abnormal air inhaling from air intake system, PCV valve and EVAP canister purge control system.
Check TP sensor (closed throttle position) and ECT sensor for performance.
If sensors are OK, substitute a known-good ECM.
Wire harness check
1) Check that IAC valve circuit is in good condition referring to Step 4 to 9 of DTC P0505: Idle Air Control System:M13A with VVT .
Is circuit in good condition?
Go to Step 11.
Repair or replace IAC valve circuit.
IAC valve signal check
1) Connect IAC valve and ECM connectors with ignition switch turned OFF.
2) Using oscilloscope, check IAC valve signal referring to “Reference waveform No.23” and “Reference waveform No.24” under Inspection of ECM and Its Circuits:M13A with VVT .
Is duty pulse outputted as reference waveform No.23 and No.24 at “E117-8” of ECM terminal?
Replace IAC valve.
Substitute a known-good ECM and recheck.