Active Noise Cancellation Malfunction
Active Noise Cancellation Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The Active Noise Cancellation system has four main components: the active noise cancellation module, two microphones, the audio amplifier, and the vehicle speakers.
The two microphones are located in the headliner to monitor noise/sounds in the vehicle cabin, and are directly connected to the active noise cancellation module. The active noise cancellation module also receives a discrete engine speed (RPM) signal from the engine control module. The active noise cancellation module processes these two inputs to determine the frequency of the undesirable sound. The active noise cancellation module then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone) to the audio amplifier which in turn sends the signal to be output by the vehicle speakers.
Diagnostic Aids
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.
Reference Information
Schematic Reference
Active Noise Cancellation Schematics Active Noise Cancellation Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left Front
Description and Operation
Active Noise Cancellation Description and Operation Active Noise Cancellation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
1. Verify no DTCs are present.
• If any DTCs are present
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If no DTCs are present
2. Ignition ON.
3. Verify that there are no low or high response test tones heard.
• If test tones are heard
Refer to Diagnostic Mode Signal Circuit Testing.
• If test tones are not heard
4. A11 radio ON, mute OFF.
5. 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 Speaker Malfunction.
• If clear audio is heard from all speakers
6. Place the active noise cancellation module into diagnostic mode: Install a 3 A fuse jumper wire between the X51A fuse block spare fuse 3 and ground.
7. Verify that a low response test tone is heard from the front speakers indicating the module has entered diagnostic mode.
• If the low response test tone is not heard
Refer to Active Noise Cancellation Module and Front Speaker Circuit Testing.
• If the low response test tone is heard
8. Verify that a high response tone is heard from the front speakers, after the low response test tone is heard.
• If the high response test tone is not heard
Refer to Front Microphone Circuit Testing.
• If the high response test tone is heard
9. Verify that a low test tone is heard from the subwoofer, after the high response tone is heard from the front speakers.
• If the low response test tone is not heard
Refer to Rear Speaker Circuit Testing.
• If the low response test tone is heard
10. Verify that a high response tone is heard from the rear speakers, after the low response test tone is heard from the subwoofer.
• If the high response test tone is not heard
Refer to Rear Microphone Circuit Testing.
• If the high response test tone is heard
11. Refer to Engine RPM Signal Circuit Testing.
Circuit/System Testing
Diagnostic Mode Signal Circuit Testing
1. Ignition ON.
2. Verify that there are no low or high response test tones heard.
• If test tones are heard
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module.
2. Test for infinite resistance between the control circuit terminal 6 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If test tones are not heard
3. Test or replace the K108 active noise cancellation module.
Active Noise Cancellation Module and Front Speaker Circuit Testing
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module.
2. Test for less than 10 ohms between the ground circuit terminal 11 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
3. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, refer to Power Mode Mismatch Power Mode Mismatch.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K108 active noise cancellation module.
• If the test lamp illuminates
4. Ignition ON, A11 radio ON.
5. Verify a test lamp illuminates between the control circuit terminal 2 and ground.
• If the test lamp does not illuminate
1. Ignition OFF. Disconnect the X1 harness at the A11 radio.
2. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the A11 radio.
• If the test lamp illuminates
6. Test for less than 2 ohms between the K108 active noise cancellation module terminal 6 and the X51A fuse block spare fuse 3.
• If 2 ohms or greater
Repair the open/high resistance in the circuit.
• If less than 2 ohms.
7. Ignition OFF, connect the harness connector at the K108 active noise cancellation module. Disconnect the X2 harness connector at the T3 audio amplifier. Ignition ON, radio ON.
8. Test for 5-7 V between the signal circuit terminals listed below and ground:
* Front noise cancellation signal (+) - terminal 14
* Front noise cancellation signal (-) - terminal 13
• If less than 5 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation 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 K108 active noise cancellation module.
• If greater than 7 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module. 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 K108 active noise cancellation module.
• If between 5-7 V
9. Test or replace the K108 active noise cancellation module.
Front Microphone Circuit Testing
1. Ignition OFF, disconnect the harness connector at the B277F front interior noise cancellation microphone.
2. Test for less than 10 ohms between the low reference circuit terminal A and ground.
• If 10 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K108 active noise cancellation module.
• If less than 10 ohms
3. Ignition ON.
4. Test for 8-10 V between the signal circuit terminal B and ground.
• If less than 8 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation 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 K108 active noise cancellation module.
• If greater than 10 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module. 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 K108 active noise cancellation module.
• If between 8-10 V
5. Test or replace the B277F front interior noise cancellation microphone.
Rear Speaker Circuit Testing
1. Ignition OFF, disconnect the X2 harness connector at the T3 audio amplifier.
2. Test for 5-7 V between the signal circuit terminals listed below and ground:
* Rear noise cancellation signal (+) - terminal 15
* Rear noise cancellation signal (-) - terminal 16
• If less than 5 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation 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 K108 active noise cancellation module.
• If greater than 7 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module. 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 K108 active noise cancellation module.
• If between 5-7 V
3. Test or replace the T3 audio amplifier.
Rear Microphone Circuit Testing
1. Ignition OFF, disconnect the harness connector at the B277R rear interior noise cancellation microphone.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal A and ground.
• If 10 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K108 active noise cancellation module.
• If less than 10 ohms
3. Ignition ON.
4. Test for 8-10 V between the signal circuit terminal B and ground.
• If less than 8 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation 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 K108 active noise cancellation module.
• If greater than 10 V
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module. 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 K108 active noise cancellation module.
• If between 8-10 V
5. Test or replace the B277R rear interior noise cancellation microphone.
Engine RPM Signal Circuit Testing
1. Ignition OFF, disconnect the harness connector at the K108 active noise cancellation module. Engine Running.
2. Test for 20-30 Hz DC between the signal circuit terminal 5 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 K108 active noise cancellation module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Radio Volume Compensator Interior Noise Microphone Replacement Service and Repair
* Control Module References Programming and Relearning for active noise cancellation module, engine control module, or radio replacement, programming, and setup.