Booming Sound While Driving With Audio Unit On or Off
Booming sound while driving with audio unit on or offNOTE: Always check the connectors for poor connections or loose terminals.
1. Turn the ignition switch ON (II).
2. Operate the audio unit, and check the function of the speakers.
Is a booming sound or a low-frequency hum heard from speakers?
YES - Go to step 3.
NO - Go to no sound is heard from speakers.
3. Open the driver's door.
Is the booming sound or a low-frequency hum still present?
YES - Perform the electrical noise test. Sound Quality Diagnosis
NO - Go to step 4.
4. Turn the audio power switch OFF.
5. Do the self-diagnostic function.
6. Press the "No. 1" button.
Can you hear the low-frequency hum sound?
YES - Go to step 7.
NO - Go to step 27.
7. Check that the low-frequency hum sound continues sounding for about 1 minute.
Does the low-frequency hum sound continue sounding for about 1 minute?
YES - Go to step 48.
NO - Go to step 8.
8. Check the No. 32 (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 9.
NO - Replace the fuse, and recheck.
9. Turn the ignition switch OFF.
10. Disconnect active noise control front microphone 4P connector and active noise control rear microphone 5P connector.
11. Turn the ignition switch ON (II) and audio unit turns ON.
12. Measure the voltage between active noise control front microphone 4P connector terminal No. 4 and rear microphone 5P connector terminal No. 2 and body ground.
Is there battery voltage?
YES - Go to step 13.
NO - Repair open in the wire between audio unit connector C (40P) terminal No. 15 and active noise control front or rear microphone connector.
13. Check for continuity between active noise control front microphone 4P connector terminal No. 3 and rear microphone 5P connector terminal No. 3 and body ground.
Is there continuity?
YES - Go to step 14.
NO - Repair open in the wire between active noise control front or rear microphone connector and body ground (G501).
14. Turn the ignition switch OFF.
15. Check for continuity between body ground and active noise control front microphone 4P connector terminal No. 1 and No. 2 and rear microphone 5P connector No. 4 and No. 5 terminals individually.
Is there continuity?
YES - Repair short in the wire between body ground and active noise control front or rear microphone.
NO - Go to step 16.
16. Reconnect the active noise control front and rear microphone connectors.
17. Turn the ignition switch ON (II).
18. Measure the voltage between the body ground and active noise control front microphone 4P connector terminals No. 1 and No. 2 and rear microphone 5P connector terminal No. 4 and No. 5 individually while lightly tapping the microphones.
Does the voltage change a lot?
YES - Go to step 19.
NO - Replace the active noise control front or rear microphone.
19. Turn the ignition switch OFF.
20. Disconnect the active noise control unit 16P connector.
21. Disconnect active noise control front microphone 4P connector.
22. Check for continuity between the active noise control unit 16P connector No. 14 terminal and active noise control front microphone 4P connector terminal No. 1.
Is there continuity?
YES - Go to step 23.
NO - Repair open in the wire between the active noise control unit 16P connector No. 14 terminal and active noise control front microphone 4P connector No. 1 terminal.
23. Check for continuity between the active noise control unit 16P connector No. 6 terminal and active noise control front microphone 4P connector terminal No. 2.
Is there continuity?
YES - Go to step 24.
NO - Repair open in the wire between the active noise control unit 16P connector No. 6 terminal and active noise control front microphone 4P connector terminal No. 2.
24. Disconnect active noise control rear microphone 5P connector.
25. Check for continuity between the active noise control unit 16P connector No. 13 terminal and active noise control rear microphone 5P connector terminal No. 5.
Is there continuity?
YES - Go to step 26.
NO - Repair open in the wire between the active noise control unit 16P connector No. 13 terminal and active noise control front microphone 5P connector terminal No. 5.
26. Check for continuity between the active noise control unit 16P connector No. 5 terminal and active noise control rear microphone 5P connector terminal No. 4.
Is there continuity?
YES - Replace the active noise control unit.
NO - Repair open in the wire between the active noise control unit 16P connector No. 5 terminal and active noise control rear microphone 5P connector terminal No. 4.
27. Check for the No. 32 (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 28.
NO - Replace the fuse, and recheck.
28. Disconnect the active noise control unit 16P connector.
29. Turn the ignition switch ON (II) and audio unit turns ON.
30. Measure the voltage between the active noise control unit 16P connector No. 9 terminal and body ground.
Is there battery voltage?
YES - Go to step 31.
NO - Repair open in the wire between audio unit connector C (40P) terminal No. 15 and the active noise control unit 16P connector terminal No. 9.
31. Turn the ignition switch OFF.
32. Reconnect the active noise control unit 16P connector.
33. Measure the voltage between the active noise control unit 16P connector No. 10 terminal and body ground.
Is there less than 0.1 V?
YES - Go to step 34.
NO - Repair open in the wire between the active noise control unit 16P connector No. 10 terminal and body ground (G506).
34. Perform the self-diagnostic function Sound Quality Diagnosis.
35. Press the "No. 1" button.
36. Measure the voltage between the active noise control unit 16P connector No. 11 terminal and body ground.
Is there about 5 V?
YES - Go to step 41.
NO - Go to step 37.
37. Turn the ignition switch OFF.
38. Disconnect the active noise control unit 16P connector and audio unit connector C (40P).
39. Check for continuity between the active noise control unit 16P connector No. 11 terminal and audio unit connector C (40P) terminal No. 36.
Is there continuity?
YES - Go to step 40.
NO - Repair open in the wire between the active noise control unit 16P connector No. 11 terminal and audio unit connector C (40P) terminal No. 36.
40. Check for continuity between body ground and the active noise control unit 16P connector terminal No. 11.
Is there continuity?
YES - Repair short in the wire between the active noise control unit 16P connector No. 11 terminal and audio unit connector C (40P) terminal No. 36.
NO - Replace the audio unit.
41. Perform the self-diagnostic function. Sound Quality Diagnosis
42. Press and release the "No. 1" button.
43. Measure the voltage between the active noise control unit 16P connector No. 15 terminal and body ground.
Is there about 2.5 V?
YES - Replace the audio unit.
NO - Go to step 44.
44. Turn the ignition switch OFF.
45. Disconnect the active noise control unit 16P connector and audio unit connector C (40P).
46. Check for continuity between the active noise control unit 16P connector and audio unit connector C (40P).
Is there continuity?
YES - Go to step 47.
NO - Repair open in the wire(s) between the active noise control unit 16P connector and audio unit connector C(40P).
47. Check for continuity between body ground and active noise control unit 16P connector terminals No. 8, 15, and 16 individually.
Is there continuity?
YES - Repair short in the wire(s) between the active noise control unit 16P connector and audio unit connector C(40P).
NO - Replace the active noise control unit.
48. Start the engine, and let the vehicle idle.
49. Perform the self-diagnostic function. Sound Quality Diagnosis
50. Press the "No. 1" button.
Can you hear the low-frequency hum?
YES - Go to step 51.
NO - The system is OK.
51. Turn the ignition switch OFF.
52. Disconnect the active noise control unit 16P connector.
53. Check for continuity between the active noise control unit 16P connector No. 2 terminal and ECM/PCM connector E (31P) terminal No. 23 with the ECM/PCM connector connected.
Is there continuity?
YES - Go to step 54.
NO - Repair open in the wire between the active noise control unit 16P connector No. 2 terminal and ECM/PCM connector E (31P) terminal No. 23.
54. Check for continuity between the active noise control unit 16P connector No. 2 terminal and body ground.
Is there continuity?
YES - Repair short in the wire between body ground and the active noise control unit 16P connector No. 2 terminal and ECM/PCM connector E (31P) terminal No. 23.
NO - Replace the ECM/PCM.