Poor AM/FM Radio Reception or Interference

Poor AM or FM radio reception or interference

NOTE: Check the radio reception in an open area. Poor reception/interference can be caused by the following:
- The radio station is far away.
- Atmospheric conditions are unfavorable.
- Tall buildings, mountains, or high-voltage power lines are nearby.

1. Do the seek stop test.

Is the number of stations the same or within 10 % of the known-good vehicle?

YES - Multipath interference or weak station. Operation is normal.

NO - Go to step 2.

2. Check if the radio 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 all of the AM/FM antenna connections and the AM/FM antenna and radio grounds. If OK, check the charging system and the ignition system.

NO - Go to step 4.

4. Check the antenna element for cracks, or other damage. Verify that the antenna element is tight and that there is no corrosion on the threads.

NOTE: Do not use any tools to tighten the antenna element.

Is there any damage?

YES - Replace the antenna element.

NO - Go to step 5.




5. Turn the radio ON, and measure the voltage between AM/FM antenna 2P connector terminal No. 2 and body ground.

Is there battery voltage?

YES - Go to step 6.

NO - Go to step 14.

6. Remove the audio unit, and disconnect the AM/FM antenna lead.
7. Disconnect the AM/FM antenna lead from the AM/FM antenna.




8. Check for continuity between the AM/FM antenna lead center pin at the audio unit side and the AM/FM antenna lead center pin at the AM/FM antenna side.

Is there continuity?

YES - Go to step 9.

NO - Replace the AM/FM antenna lead.

9. Check for continuity between the AM/FM antenna lead center pin at the audio unit and body ground.

Is there continuity?

YES - Replace the AM/FM antenna lead.

NO - Go to step 10.




10. Check for continuity between the shield surface of the AM/FM antenna lead at the audio unit side and the shield surface of the AM/FM antenna lead at the AM/FM antenna side.

Is there continuity?

YES - Go to step 11.

NO - Replace the AM/FM antenna lead.




11. Check for continuity between the AM/FM antenna lead center pin at the audio unit side and body ground.

Is there continuity?

YES - Replace the AM/FM antenna lead.

NO - Go to step 12.




12. Check for continuity between the AM/FM antenna lead center pin and the surface of the AM/FM antenna lead.

Is there continuity?

YES - Replace the AM/FM antenna lead.

NO - Go to step 13.

13. Substitute a known-good AM/FM antenna lead, and check the radio reception.

Is the reception normal?

YES - Replace the AM/FM antenna lead.

NO - Substitute a known-good audio unit and recheck. If the reception is still poor, replace the AM/FM antenna.

14. Remove the audio unit and disconnect the audio unit 20P connector.




15. Check for continuity between audio unit 20P connector terminal No. 1 and AM/FM antenna connector terminal No. 2.

Is there continuity?

YES - Substitute a known-good audio unit and retest.

NO - Repair open in the wire between the audio unit and the AM/FM antenna.