Identification Of Noise Source

WARNING: This page is about a different car, the 2004 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.

Radio Description
1. Radio frequency band
  1. Radio Broadcasts use the radio frequency bands shown in Fig 1 .
  Fig 1: Identifying Frequency Display Table
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Service area
  1. The service areas of the AM and FM broadcasts are vastly different. Even if an AM broadcast has clear reception, an FM broadcast originating in the same location may not be received at all.
    The service area of FM stereo broadcasts is small, and static as well as interference (noise) easily enters the signal.
  Fig 2: Identifying Service Area
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Radio reception problems
  HINT:
  
  In addition to static, other problems such as "phasing", "multipath", and "fade out" exist. These problems are not caused by electrical noise, but by the radio signal propagation method itself.
  1. Phasing
    The AM frequency band reflects off the earth's ionosphere at night. When this occurs, the reflected signal may interfere with the direct signal sent by the same transmitter. This phenomenon is known as "phasing".
    
    Fig 3: Identifying Phasing (Ionosphere)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Multipath
    A radio signal can sometimes be reflected by an obstruction in its path. When this occurs, the reflected signal may interfere with the direct signal sent from the transmitter. This phenomenon is known as "multipath".
    
    Fig 4: Identifying Multipath
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Fade out
    FM radio frequency is higher than AM. Therefore, it is more likely to be reflected by large obstructions such as tall buildings or mountains. For this reason, the FM signal will gradually weaken or disappear when the vehicle is behind such obstructions. This phenomenon is known as "fade out".
  Fig 5: Identifying Fade-out
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Noise problem
  It is very important for a technician to understand the specifics of the noise problem. To diagnose the symptom, use Fig 6 .
  
  Fig 6: Radio Frequency Noise Cause Table
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  
  If the noise does not fall into any category in Fig 6 , determine the cause using "Radio reception problems" above. Refer to the Fig 4 and Fig 3 in the .
  
  SYSTEM NORMAL CONDITION CHECK
5. If the symptom is applicable to any of the following, it is intended behavior, and not a malfunction.
  
  Fig 7: System Condition Check Table
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
6. The following symptoms are not a malfunction, but are caused by errors inherent in the GPS, gyro sensor, speed sensor, and navigation ECU.
  1. The current position mark may be displayed on a nearby parallel road.
    
    Fig 8: Identifying Current Vehicle Position Mark - Parallel Road
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Immediately after a fork in the road, the current vehicle position mark may be displayed on the wrong road.
    
    Fig 9: Identifying Current Vehicle Position Mark - After Fork In Road
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. When the vehicle turns right or left at an intersection, the current vehicle position mark may be displayed on a nearby parallel road.
    
    Fig 10: Identifying Current Vehicle Position Mark - After Intersection
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. When the vehicle is carried, such as on a ferry, and the vehicle itself is not running, the current vehicle position mark may be displayed in the position where the vehicle was until a measurement can be performed by GPS.
    
    Fig 11: Identifying Current Vehicle Position Mark - On Ferry
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  5. When the vehicle runs on a steep hill, the current vehicle position mark may deviate from the correct position.
    
    Fig 12: Identifying Current Vehicle Position Mark - On Steep Hill
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. When the vehicle makes a continuous turn of 360, 720, 1,080, etc. degrees, the current vehicle position mark may deviate from the correct position.
    
    Fig 13: Identifying Current Vehicle Position Mark - On Deviations
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  7. When the vehicle moves erratically, such as constant lane changes, the current vehicle position mark may deviate from the correct position.
    
    Fig 14: Identifying Current Vehicle Position Mark - On Constant Lane Changing
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  8. When the ignition switch is turned to the ACC or ON position on a turn table before parking, the current vehicle position mark may not point in the correct direction. The same will occur when the vehicle comes out of parking.
    
    Fig 15: Identifying Current Vehicle Position Mark - Turning Ignition On
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  9. When the vehicle runs on the snowy road or a mountain path with the chains installed or using a spare tire, the current vehicle position mark may deviate from the correct position.
    
    Fig 16: Identifying Current Vehicle Position Mark - When On Snowy Road
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  10. When a tire is changed, the current vehicle position mark may deviate from the correct position.
  HINT:
  - Diameter of the tire may change, causing a speed sensor error.
  - Performing the "tire change" in calibration mode will allow the system to correct the current vehicle position faster.
  Fig 17: Identifying Current Vehicle Position Mark - When Tire Changing
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002