Chevrolet Trax: Active Noise Cancellation

SCHEMATIC WIRING DIAGRAMS

ACTIVE NOISE SYSTEM CANCELLATION WIRING SCHEMATICS (ENCORE)

Active Noise Cancellation (NKC)

Fig. 1: Active Noise Cancellation (NKC)

DIAGNOSTIC INFORMATION AND PROCEDURES

ACTIVE NOISE CANCELLATION MALFUNCTION

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The Active Noise Cancellation system has three main components: Three microphones, the audio amplifier, and the vehicle speakers.

The three microphones are located in the headliner to monitor noise/sounds in the vehicle cabin, and are directly connected to the amplifier. The amplifier also receives a discrete engine speed (RPM) signal from the engine control module. The amplifier processes these two inputs to determine the frequency of the undesirable sound.

The amplifier then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone), which in turn sends the signal to be output by the vehicle speakers.

Diagnostic Aids

The active noise cancellation system is designed to moderate particular frequencies of engine noise, not to create a noise-free vehicle cabin. The system is not designed to cancel any wind or road noise. The system is intended to cancel unwanted engine sound from 1000 to 4600 RPM.

Reference Information

Description and Operation

Active Noise Cancellation Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Circuit/System Verification

1. A11 radio ON, mute OFF.
2. Verify clear audio is heard from each speaker, adjusting fade and balance controls to test each speaker individually.

If audio is inoperative from one or more speakers, or the audio emitted is not clear

Refer to Speaker Malfunction .

Circuit/System Testing

Interior Noise Cancellation Microphone Circuit Testing

NOTE: Vehicles with Active Noise Cancellation will be equipped with 3 Interior Noise Cancellation Microphones (2 front and 1 rear). The following test will need to be performed on each Interior Noise Cancellation Microphone.

Microphone Malfunction

1. Ignition OFF, disconnect the harness connector at the Interior Noise Cancellation Microphone, ignition ON.
2. Test for 8.0-10.5 V between the signal circuit terminal B and ground.

If less than 8.0 V

1. Ignition OFF, disconnect the X2 harness connector at the T3 Amplifier.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the vehicle T3 Amplifier

If greater than 10.5 V

1. Ignition OFF, disconnect the X2 harness connector at the T3 Amplifier, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the T3 Amplifier.

If between 8.0-10.5 V

3. Test for less than 1 V between the signal circuit terminal A and ground.

If greater than 1 V

1. Ignition OFF, disconnect the X2 harness connector at the T3 Amplifier, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage in the circuit.
• If less than 1 V, repair the T3 Amplifier.

If less than 1 V

4. Test 8 V or less between the signal circuit terminal B and the signal circuit terminal A.

If less than 8 V

1. Ignition OFF, disconnect the X2 harness connector at the T3 Amplifier.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the vehicle T3 Amplifier.

If greater than 8 V

5. Test or replace the Interior Noise Cancellation Microphone.

Engine RPM Signal Circuit Testing

1. Ignition OFF, disconnect the X2 harness connector at the T3 Audio Amplifier. Engine Running.
2. Test for 20-30 Hz DC between the signal circuit terminal 12 and ground.

If not 20-30 Hz

1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.

If 20-30 Hz

3. Test or replace the T3 Audio Amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Radio Speaker Amplifier Replacement

DESCRIPTION AND OPERATION

ACTIVE NOISE CANCELLATION DESCRIPTION AND OPERATION

The entertainment system on this vehicle may have several different configurations. To determine the specific configuration of the vehicle, please see the Service Parts ID Label, and refer to RPO Code List (Chevrolet) , RPO Code List (Buick) .

The Active Noise Cancellation system is a method used to reduce the perception of certain undesirable sounds generated by the engine. The active noise cancellation system analyzes the noise signal and outputs a cancellation signal audio tone to moderate the engine noise and make the vehicle cabin seem quieter and without vibration

Active Noise Cancellation Operation

The Active Noise Cancellation system has three main components: Three microphones, the audio amplifier, and the vehicle speakers.

The three microphones are located in the headliner to monitor noise/sounds in the vehicle cabin, and are directly connected to the amplifier. The amplifier also receives a discrete engine speed (RPM) signal from the engine control module. The amplifier processes these two inputs to determine the frequency of the undesirable sound.

The amplifier then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone), which in turn sends the signal to be output by the vehicle speakers.

The amplifier performs a self-diagnostic check ensuring that the speaker and microphone circuits are appropriately enabled and then enables Active Noise Cancellation. The Active Noise Cancellation itself however does not have a self test to diagnose itself. There are no DTC's set in the amplifier.

The active noise cancellation system is designed to moderate particular frequencies of engine noise, not to create a noise-free vehicle cabin. The system is not designed to cancel any wind or road noise. The system is intended to cancel unwanted engine sound from 1000 to 4600 RPM.

On the base 6 speaker system, the subwoofer is not used for reproducing audio. The subwoofer is used only for producing the cancellation tones for the active noise cancellation system. On the uplevel speaker system, the subwoofer is used for both reproducing audio and the active noise cancellation system tones.

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