Symptom Troubleshooting
Audio System Symptom Troubleshooting - Poor AM or FM radio reception or interference
Poor AM or FM radio reception or interference
NOTE:
- Check the vehicle battery condition first Testing and Inspection.
- Check the connectors for poor connection or loose terminals.
- Check the radio reception in an open area. Poor reception/interference can be caused by any of these conditions:
- The radio station is too far away.
- Atmospheric conditions are unfavorable.
- Aftermarket metallic window tinting can affect reception on vehicles with window antennas. If the vehicle has aftermarket metallic window tinting, advise your client that it would have to be removed for proper testing.
- A tall buildings, mountains, or a high-voltage power lines are nearby.
1. Do the seek stop test and check the radio reception/interference.
Is the test vehicle within 10 % of the known-good vehicle?
YES -
Multipath interference or weak station. Operation is normal.�
NO -
Go to step 2.
2. Check that the reception/interference is the same in several locations.
Is the reception/interference the same?
YES -
Go to step 3.
NO -
Multipath interference or weak station. Operation is normal.�
3. Check the reception/interference while the engine is running.
Is there noise (static or whine) only with the engine running?
YES -
Check the antenna and radio grounds. If OK, check the charging system and the ignition system.�
NO -
Go to step 4.
4. Turn the ignition switch to LOCK (0).
5. Wrap aluminum foil (A) around the tip of a tester probe (B) as shown.
6. Touch one tester probe to the window near the antenna terminal (A), and move the other tester probe along the antenna wires to check for continuity. Repair if there is no continuity.
7. Remove the audio unit Audio Unit Removal / Installation. Check the audio unit connector E (5P) connection.
Is it properly connected?
YES -
Go to step 8.
NO -
Reconnect the audio unit connector E (5P), and recheck the function.�
8. Disconnect the AM/FM antenna amplifier 3P connector Service and Repair.
9. Turn the ignition switch to ON (II).
10. Turn on the audio unit, and select AM or FM.
11. Measure the voltage between AM/FM main antenna amplifier 3P connector terminal No. 3 AM/FM antenna amplifier lead and body ground.
Is there battery voltage?
YES -
Go to step 17.
NO -
Go to step 12.
12. Turn the ignition switch to LOCK (0).
13. Remove the audio unit Audio Unit Removal / Installation.
14. Disconnect audio unit connector E (5P).
15. Check for continuity between audio unit connector E (5P) terminal No. 5 and AM/FM main antenna amplifier 3P connector terminal No. 3.
Is there continuity?
YES -
Go to step 16.
NO -
Repair an open in the wire between the audio unit and the main antenna amplifier. Also check the AM/FM antenna lead/sublead connector.�
16. Check for continuity between audio unit connector E (5P) terminal No. 5 and body ground.
Is there continuity?
YES -
Repair a short to body ground in the wire between the audio unit and the AM/FM main or sub antenna amplifier.�
NO -
Substitute a known-good audio unit Audio Unit Removal / Installation, and recheck. If the symptom goes away, replace the original audio unit Audio Unit Removal / Installation.�
17. Remove the audio unit Audio Unit Removal / Installation.
18. Disconnect the audio unit connector E (5P).
19. Check for continuity between audio unit connector E (5P) terminal No. 3 and AM/FM main antenna amplifier 3P connector terminal No. 1.
Is there continuity?
YES -
Go to step 20.
NO -
Replace the AM/FM antenna sublead and/or main lead.�
20. Check for continuity between audio unit connector E (5P) terminal No. 3 and body ground.
Is there continuity?
YES -
Replace the AM/FM antenna sublead and/or main lead.�
NO -
Go to step 21.
21. Check for continuity between audio unit connector E (5P) terminal No. 4 and AM/FM main antenna amplifier 3P connector terminal No. 2.
Is there continuity?
YES -
Go to step 22.
NO -
Replace the AM/FM antenna sublead and/or main lead.�
22. Check for continuity between audio unit connector E (5P) terminals No. 3 and No. 4.
Is there continuity?
YES -
Replace the AM/FM antenna sublead and/or main lead.�
NO -
Go to step 23.
23. Check for continuity between audio unit connector E (5P) terminal No. 1 and AM/FM subantenna amplifier 3P connector terminal No. 1.
Is there continuity?
YES -
Go to step 24.
NO -
Replace the AM/FM antenna sublead and/or main lead.�
24. Check for continuity between audio unit connector E (5P) terminal No. 1 and body ground.
Is there continuity?
YES -
Replace the AM/FM antenna sublead and/or main lead.�
NO -
Go to step 25.
25. Check for continuity between audio unit connector E (5P) terminal No. 2 and AM/FM subantenna amplifier 3P connector terminal No. 2.
Is there continuity?
YES -
Go to step 26.
NO -
Replace the AM/FM antenna sublead and/or main lead.�
26. Check for continuity between audio unit connector E (5P) terminals No. 1 and No. 2.
Is there continuity?
YES -
Replace the AM/FM antenna sublead and/or main lead.�
NO -
Replace the AM/FM antenna amplifier Service and Repair, and recheck. If the reception is still poor, replace the audio unit Audio Unit Removal / Installation.�