Idle Speed Control System — Description (Honda HR-V 1)

The engine's idle speed is controlled by the IAC valve. The valve varies the amount of air supplied to the intake manifold, bypassing the throttle valve, in response to an electrical signal generated by the ECM/PCM. When the IAC valve is activated, it opens and maintains the proper idle speed (see figure below).

1. After the engine starts, the IAC valve opens for a while. Air flow increases, increasing idle speed by approximately 150-300 rpm (min⁻¹).

2. When the coolant temperature is low, the IAC valve opens and the required fast idle speed is achieved. Thus, the bypass air flow rate is adjusted according to the engine coolant temperature.

3. When the idle speed is different from normal, but the malfunction indicator lamp (MIL) does not indicate diagnostic trouble code (DTC) 14, check the following items:

• Signal from the air conditioner
• Signal from ALT FR
• Signal from the brake light switch
• Signal from the starter
• Signal from PSP switch
• Signal from the automatic transmission selector switch
• Hoses and fittings
• IAC valve and its O-rings

4. If the above items are normal, but the MIL does not set DTC14 after replacing the IAC valve, substitute a known-good ECM/PCM and retest. If the symptom is corrected, replace the original ECM/PCM.



(Original article on the website «HondaBook.ru»)