Active Noise Cancellation (ANC) System
The audio system includes an active noise cancellation (ANC) system to cancel some of the vehicle noise. The audio unit receives the engine speed pulse (NEP) from the PCM and outputs a sine-wave-sound through the audio speakers to cancel low-frequency noise from the engine. The ANC system also uses two microphones to detect and monitor low frequency noise in the passenger compartment. The microphones feed information back to the audio unit which adjusts the speaker output to reduce the noise. The ANC also receives input from the door open/close (INTR LT) signal from the MICU via the B-CAN. Anytime a door is opened, the ANC system temporarily stops working.
Scheme 37
Active Noise Cancellation (ANC) System Check Mode
Note. Not all self-diagnostic functions appear on all models. There may be other self-diagnostic functions that are for factory use only. Only perform this test when you are guided from a troubleshooting procedure. This test does not work with aftermarket speakers or amplifiers. All components must be OEM to do this test.
Scheme 38
Scheme 39
Scheme 40
- Turn the ignition switch to ON (II).
- Make sure the audio system is turned off.
- Push and hold the preset No. 1 and No. 6 buttons.
- While holding the buttons, push the VOL PUSH PWR knob to ON.
- Press the No. 1 button, then the active noise cancellation (ANC) system check mode begins. How to check the active noise cancellation system in this check mode While in this system check mode, press the No. 1 button to move to the next test. You must remember how many times you pressed the No. 1 button. The system will not show which test item you are doing. For test items 1 thru 10, the speaker makes a low-frequency hum (50 Hz) when the system is normal for 5 seconds up to 1 minute. When there is a failure in the system, the speaker will not make a low-frequency hum (50 Hz) or the hum stops within 5 seconds for tests 1 thru 10. The check mode automatically cancels when the time reaches 1 minute after starting each test. When you reach the 11th test item, the test loops ON and OFF doing the 11th test each time you press the No. 1 button. It does not move to a new test. This check mode ends when you start the engine (ignition switch in START (III)), because power to the audio system is cut off when the ignition switch is in START (III). This test is not available to do all items at once. If you need to use the 2nd, 7th, or 11th test, start the check mode with the engine idling. If you need to check test item 9th and/or 10th, start the check mode with the engine stopped. Other test items are available in both conditions. AUDIO UNIT OPERATION TABLE Test Item No. Test Item Button Operation Number of times No. 1 Button Pressed Display ON/OFF Sound from Speakers when System is Normal Test Available Condition - Self-Diagnostic mode enter Turn audio unit off, press and hold preset buttons No. 1 and No. 6, press the VOL PUSH PWR knob to on. - - None - 1st Microphone input, speaker output No. 1 1 ON None Any conditions No. 1 2 OFF 50 Hz hum for 1 minute 2nd NEP input, door/trunk switch input No. 1 3 ON None Engine idling All doors/trunk closed No. 1 4 OFF 50 Hz hum for 1 minute 3rd Front speaker output No. 1 5 ON None Any conditions No. 1 6 OFF 50 Hz hum for 1 minute 4th Rear speaker output No. 1 7 ON None Any conditions No. 1 8 OFF 50 Hz hum for 1 minute 5th ANC front microphone input No. 1 9 ON None Any conditions No. 1 10 OFF 50 Hz hum for 1 minute 6th ANC rear microphone input No. 1 11 ON None Any conditions No. 1 12 OFF 50 Hz hum for 1 minute 7th NEP (engine speed signal) input No. 1 13 ON None Engine idling No. 1 14 OFF 50 Hz hum for 1 minute 8th Door/trunk switch input No. 1 15 ON None All doors/trunk closed No. 1 16 OFF 50 Hz hum for 1 minute 9th CSSAMA signal (VCM3 cylinder mode) input No. 1 17 ON None Ignition switch in ON (II) + HDS operation (1) No. 1 18 OFF 50 Hz hum for 1 minute 10th CSSAMC signal (VCM4 cylinder mode) input No. 1 19 ON None Ignition switch in ON (II) + HDS operation (2) No. 1 20 OFF 50 Hz hum for 1 minute 11th ANC operation ON/OFF No. 1 21 ON None Engine speed about 2, 500 rpm in neutral No. 1 22 OFF Engine noise reduced (1) On test item 8th, select PGM-FI, INSPECTION, SOLENOID VALVE ACTIVATION, ROCKER ARM OIL CONTROL SOLENOID A ON, then press No. 1 button and check test item 9th. (2) On test item 9th, select PGM-FI, INSPECTION, SOLENOID VALVE ACTIVATION, ROCKER ARM OIL CONTROL SOLENOID C ON, then press No. 1 button and check test item 10th. Screen indication ON Screen indication OFF Canceling the ANC System Check Mode
- The self-diagnostic function ends when the ignition switch is turned to LOCK (0).