Navigation System - Diagnostics: Description

HINT:

Notice where navigation begins, the description is for the audio system. The navigation system should start with "How to proceed with troubleshooting", which is found on HOW TO PROCEED WITH TROUBLESHOOTING .

1. RADIO WAVE BAND 

   The radio wave bands used in radio broadcasting are as follows:

   Fig 1: Radio Wave Band Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. SERVICE AREA 
   1. There are great differences in the size of the service area for AM and FM broadcasting. Sometimes FM stereo broadcast cannot be received even through AM can be received very clearly.

      Not only does FM stereo have the smallest service area, but it also picks up static and other types of interference ("noise") easily.

   Fig 2: Identifying AM And FM Broadcasting Service Area

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. RECEPTION PROBLEMS 

   HINT:

   Besides the problem of static, there are also the problems called "phasing", "multipath" and "fade out". These problems are caused not by electrical noise but by the nature of the radio waves themselves.

   1. Phasing

      Besides electrical interference, AM broadcasts are also susceptible to other types of interference, especially at night. This is because AM radio waves bounce off the ionosphere at night. These radio waves then interfere with the signals from the same transmitter that reach the vehicle's antenna directly. This type of interference is called "phasing".

      Fig 3: Identifying Radio Waves Reception Problems - Phasing

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Multipath

      Interference caused by reflection of radio waves against obstructions is called "Multipath". Multipath occurs when radio signals emitted from the broadcast transmitter antenna are reflected against tall buildings or mountains and interfere with other signals which is to be received directly.

      Fig 4: Identifying Radio Waves Reception Problems - Multipath

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Fade Out

      Because of the frequency higher than that of AM, FM radio wave tends to be reflected against obstructions such as tall buildings or mountains. For this reason, FM signals often seems to gradually disappear or fade away as the vehicle goes behind those obstructions. This phenomenon is called "fade out".

   Fig 5: Identifying Radio Waves Reception Problems - Fade Out

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. NOISE PROBLEMS 
   1. It is very important to understand a customer's claim clearly in the noise troubleshooting. Use the following table to diagnose the phenomenon.
   NOISE PROBLEMS
   
   

   Radio wave	Condition in which noise occurs	Probable cause
   AM	Noise occurs at a specific place.	Strong possibility of foreign noise.
   	Noise occurs when listening to faint broadcasting.	The same program may be broadcasted from some local stations. If the program is the same, one of those may be tuned in.
   FM	Noise occurs only at night.	Strong possibility of beat from a distant broadcasting.
   	Noise occurs at a specific place during driving.	Strong possibility of multipath noise and phasing noise caused by changes of FM frequency.

   HINT:

   If the condition where the noise occurs does not meet any of the above, find out the cause based on "Reception Problems". Refer to the description about Multipath and Fading mentioned previously.

5. COMPACT DISC PLAYER 
   1. Compact Disc (hereafter called "CD") Players use a laser beam pick-up to read the digital signals recorded on the CD and reproduce analog signals of the music, etc. There are 4.7 in. (12 cm) and 3.2 in. (8 cm) discs available for the CD player.

   HINT:

   Never attempt to disassemble or oil any part of the player unit. Do not insert any object other than a disc into the magazine.

   NOTE: CD players use an invisible laser beam which could cause hazardous radiation exposure. Be sure to operate the player correctly as instructed.
6. COMPACT DISC PLAYER (DISC CLEANING) 

   If the disc gets dirty, clean the disc by wiping the surface from the center to outside in the radial directions with a soft cloth.

   NOTE: Do not use a conventional record cleaner or anti-static preservative.
   Fig 6: Cleaning Disc With Soft Cloth

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
7. COMMUNICATION SYSTEM 
   1. Components in the audio system communicate each other though LAN. (Radio receiver with CD changer control function)
   2. The master component of LAN is the navigation receiver assy with a resistance, which is necessary for communication.
   3. When short circuit or circuit breakdown occurs in the LAN circuit, the audio system does not operate normally due to the communication cutoff.
8. DIAGNOSIS FUNCTION 
   1. The audio system has diagnosis function. (The diagnosis result is displayed on the CRT display of the radio receiver assy)
   2. The component code (physical address), or three-digit number (in hexadecimal) is set for each component comprising LAN.
   3. The logical address, or two-digit number (in hexadecimal) is set for each function and component unit in each component.