Booming Sound While Driving With Audio Unit On or Off
Booming sound while driving with audio unit on or offNOTE: Check the vehicle battery condition first.
1. Check for the No.8 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 2.
NO - Replace the fuse, and recheck.
2. Turn the ignition switch ON (II).
3. Turn on the audio unit, and check the function of the speakers.
Do all the speakers operate normally?
YES - Go to step 4.
NO - Go to no sound is heard from speakers.
4. Turn the audio power switch OFF.
5. Do the self-diagnostic procedure.
6. Press the "No.1" button.
Is the low-frequency hum sound heard?
YES - Go to step 7.
NO - Go to step 21.
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. Measure the voltage between the active noise control front or rear microphone 5P connector terminal No.4 and body ground.
Is there battery voltage?
YES - Go to step 9.
NO - Repair open in the wire between the No.8 (7.5 A) in the driver's under-dash fuse/relay box and the active noise control rear microphone 5P connector.
9. Measure the voltage between the active noise control rear microphone 5P connector terminal No.3 and body ground.
Is there less than 0.1 V?
YES - Go to step 10.
NO - Repair open or poor connection in the wire between active noise control rear microphone 5P connector No.3 terminal and body ground (G503).
10. Turn the ignition switch OFF.
11. Disconnect the active noise control rear microphone 5P connector.
12. Check for continuity between body ground and the active noise control rear microphone 5P connector No.1 and No.2 terminals individually.
Is there continuity?
YES - Repair short to body ground in the wire between body ground and the active noise control rear microphone 5P connector terminals No.1 and No.2.
NO - Go to step 13.
13. Reconnect the active noise control rear microphone connectors:
14. Turn the ignition switch ON (II).
15. Measure the voltage between the body ground and the active noise control rear microphone 5P connector terminals No.1 and No.2 individually while lightly tapping the rear microphone.
Does the voltage fluctuate?
YES - Go to step 16.
NO - Replace the active noise control rear microphone.
16. Turn the ignition switch OFF.
17. Disconnect the active noise control unit 16P connector.
18. Disconnect the active noise control rear microphone 5P connector.
19. Check for continuity between the active noise control unit 16P connector No.3 terminal and the active noise control rear microphone 5P connector terminal No.1.
Is there continuity?
YES - Go to step 20.
NO - Repair open in the wire between the active noise control unit 16P connector No.3 terminal and the active noise control front microphone 5P connector terminal No.1.
20. Check for continuity between the active noise control unit 16P connector No. 11 terminal and the active noise control rear microphone 5P connector terminal No. 2.
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.11 terminal and the active noise control rear microphone 5P connector terminal No.2.
21. Turn the ignition switch ON (II).
22. Measure the voltage between the active noise control unit 16P connector No.8 terminal and body ground.
Is there battery voltage?
YES - Go to step 23.
NO - Repair open in the wire between the No.8 (7.5 A) fuse in the driver's under-dash fuse/relay box and the active noise control unit 16P connector terminal No.8.
23. Measure the voltage between the active noise control unit 16P connector No.7 terminal and body ground.
Is there less than 0.1 V?
YES - Go to step 24.
NO - Repair open in the wire between the active noise control unit 16P connector No.7 terminal and the body ground (G401).
24. Do the self-diagnostic procedure.
25. Press the "No.1" button.
26. Measure the voltage between the active noise control unit 16P connector No.12 terminal and body ground.
Is there about 5 V?
YES - Go to step 37.
NO-
- Except LX models: Go to step 27.
- LX model: Go to step 32.
27. Turn the ignition switch OFF.
28. Remove the audio unit, and disconnect audio unit connector B (14P).
NOTE: Eject all the discs before removing the audio unit to prevent damaging the CD player's load mechanism.
29. Disconnect the active noise control unit 16P connector.
30. Check for continuity between the active noise control unit 16P connector No.12 terminal and audio unit connector B (14P) terminal No.6.
Is there continuity?
YES - Go to step 31.
NO - Repair open in the wire between the active noise control unit 16P connector No.12 terminal and audio unit connector B (14P) terminal No.6.
31. Check for continuity between body ground and the active noise control unit 16P connector terminal No. 12.
Is there continuity?
YES - Repair short to body ground in the wire between the active noise control unit 16P connector No.12 terminal and audio unit connector B (14P) terminal No.6.
NO - Replace the audio unit.
32. Turn the ignition switch OFF.
33. Remove the audio unit, and disconnect audio unit connector B (5P).
NOTE: Eject all the discs before removing the audio unit to prevent damaging the CD player's load mechanism.
34. Disconnect the active noise control unit 16P connector and audio unit connector B (5P).
35. Check for continuity between the active noise control unit 16P connector No.12 terminal and audio unit connector B (5P) terminal No.5.
Is there continuity?
YES - Go to step 36.
NO - Repair open in the wire between the active noise control unit 16P connector No.12 terminal and audio unit connector B (5P) terminal No.5.
36. Check for continuity between body ground and the active noise control unit 16P connector terminal No.12.
Is there continuity?
YES - Repair short to body ground in the wire between the active noise control unit 16P connector No.12 terminal and audio unit connector B (5P) terminal No.5.
NO - Replace the audio unit.
37. Press and release the "No.1" button, then measure the voltage between the active noise control unit 16P connector No.2 terminal and body ground.
Is there about 2.5 V?
YES - Replace the audio unit.
NO -
- Except LX models: Go to step 38.
- LX model: Go to step 43.
38. Turn the ignition switch OFF.
39. Remove the audio unit, and disconnect audio unit connector B (14P).
NOTE: Eject all the discs before removing the audio unit to prevent damaging the CD player's load mechanism.
40. Disconnect the active noise control unit 16P connector and audio unit connector B (14P).
41. Check for continuity between the active noise control unit 16P connector and audio unit connector B (14P) as shown.
Is there continuity?
YES - Go to step 42.
NO - Repair open in the wire(s) between the active noise control unit 16P connector and audio unit connector B (14P).
42. Check for continuity between body ground and the active noise control unit 16P connector No. 1, 2, 9 and 10 individually.
Is there continuity?
YES - Repair short to body ground in the wire(s) between the active noise control unit 16P connector and audio unit connector B (14P).
NO - Replace the active noise control unit.
43. Turn the ignition switch OFF.
44. Remove the audio unit, and disconnect audio unit connector B (5P).
NOTE: Eject all the discs before removing the audio unit to prevent damaging the CD player's load mechanism.
45. Disconnect the active noise control unit 16P connector.
46. Check for continuity between the active noise control unit 16P connector and audio unit connector B (5P) as shown.
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 B (5P).
47. Check for continuity between body ground and the active noise control unit 16P connector No. 1, 2, 9 and 10 individually.
Is there continuity?
YES - Repair short to body ground in the wire between the active noise control unit 16P connector and audio unit connector B (5P).
NO - Replace the active noise control unit.
48. Start the engine and let it idle.
49. Press the "No.1" button.
Is the low-frequency hum sound heard?
YES - Go to step 50.
NO - The system is OK.
50. Turn the ignition switch OFF.
51. Disconnect the active noise control unit 16P connector and PCM connector A (31P).
52. Check for continuity between the active noise control unit 16P connector No.15 terminal and PCM connector A (44P) terminal No.28.
Is there continuity?
YES - Go to step 53.
NO - Repair open in the wire between the active noise control unit 16P connector No.15 terminal and PCM connector A (44P) terminal No. 28.
53. Check for continuity between the active noise control unit 16P connector No.15 terminal and body ground.
Is there continuity?
YES - Repair short to body ground in the wire between body ground and the active noise control unit 16P connector No.15 terminal and PCM connector A (44P) terminal No.28.
NO - Faulty the PCM.