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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.
  • Check the connectors for poor connections or loose terminals.
  • Check the radio reception in an open area.
  • Compare it to a known-good vehicle of the same model, year, and trim level whenever possible.
  • If necessary, have the customer demonstrate the symptom.
  • 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.
    -
    Non-standard antenna element.
  1. Check if the radio reception/interference is the same as the known-good vehicle in several locations.
Is the reception/interference the same?
YES -
Go to Step 2 .
NO -
Multipath interference or weak station. Operation is normal.■
  1. Check the reception/interference while the engine is running, and compare it to the known-good vehicle.
Is there noise (static or whine) only with the engine running?
YES -
Check the antenna and radio grounds. If OK, check the charging system, fuel injection system (fuel pump), HVAC (blower motor), and the ignition system.■
NO -
Go to Step 3 .
  1. Make sure turn the ignition switch to LOCK (0).
  1. Check the AM/FM antenna element for cracks, or other damage. Make sure that the AM/FM antenna element isn't loose.
    NOTE: Do not use any tools to tighten the AM/FM antenna element.
Is there any damage?
YES -
NO -
Go to Step 5 .
  1. Disconnect AM/FM antenna 3P connector.
  1. Turn the ignition switch to ON (II).
  1. Turn on the audio unit.
  1. Measure the voltage between the AM/FM antenna 3P connector No. 3 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 14 .
NO -
Go to Step 9 .
  1. Turn the ignition switch to LOCK (0).
  1. Turn the ignition switch to ON (II).
  1. Turn on the audio unit.

  1. Measure the voltage between audio unit connector D (3P) No. 3 terminal and body ground with the audio unit connectors connected.
Is there battery voltage?
YES -
Repair open or short in the wire between audio unit and AM/FM antenna. Also check the AM/FM antenna lead/sublead connector.■
NO -
  1. Turn the ignition switch to LOCK (0).
  1. Remove the audio unit, and disconnect audio unit connector D (3P).

  1. Check for continuity between audio unit connector D (3P) terminal No. 1 and body ground.
Is there continuity?
YES -
Replace the AM/FM antenna lead and/or sublead.■
NO -
Go to Step 17 .

  1. Check for continuity between audio unit connector D (3P) No. 1 and No. 2 terminals.
Is there continuity?
YES -
Replace the AM/FM antenna lead and/or sublead.■
NO -
Go to Step 18 .

  1. Check for continuity between audio unit connector D (3P) No. 1 terminal and the AM/FM antenna 3P connector No. 1 terminal.
Is there continuity?
YES -
Go to Step 19 .
NO -
Replace the AM/FM antenna lead and/or sublead.■

  1. Check for continuity between audio unit connector D (3P) No. 2 terminal and the AM/FM antenna 3P connector No. 2 terminal.
Is there continuity?
YES -
Substitute a known-good AM/FM antenna and recheck. If the reception is still poor, replace the audio unit.
NO -
Replace the AM/FM antenna lead and/or sublead.■