Navigation System Symptom Troubleshooting - Audio-navigation unit will not turn on (No information display and no sound) (With Display Audio)

NOTE: 

• Check the vehicle 12 volt battery condition first .
• Check if the Day/Night button has been pressed, and turned off the display (see the Owner's Manual for more information).
• Check the connectors for poor connections or loose terminals.

• 1. Problem verification:

  - 1. Turn the vehicle to the ON mode.

  - 2. Check if the audio-navigation unit display indicates any information.

  Is any information displayed?

  YES 

  Intermittent failure, the system is OK at this time.

  NO 

  The failure is duplicated, go to step 2.

• 2. Fuse check:

  - 1. Turn the vehicle to the OFF (LOCK) mode.

  - 2. Check the following fuses.

  Fuse	No. A29 (10 A)
  Location	Under-hood fuse/relay box

  Fuse	No. B19 (7.5 A)
  Location	Under-dash fuse/relay box

  Are the fuses OK?

  YES 

  Go to step 3.

  NO 

  Replace the fuse(s), and recheck. If the fuse(s) blows again, check for a short in the No. A29 (10 A) fuse and/or the No. B19 (7.5 A) fuse circuits.

• 3. Open wire check (+B BACK UP line):

  - 1. Measure the voltage between test points 1 and 2.

  Test condition	Vehicle OFF (LOCK) mode
  Test point 1	Audio-navigation unit connector A (24P) No. 3
  Test point 2	Body ground

  Is there battery voltage?

  YES 

  The +B BACK UP wire is OK. Go to step 4.

  NO 

  Repair an open in the wire between the No. A29 (10 A) fuse in the under-hood fuse/relay box and the audio-navigation unit.

• 4. Open wire check (ACC line):

  - 1. Turn the vehicle to the ON mode.

  - 2. Measure the voltage between test points 1 and 2.

  Test condition	Vehicle ON mode
  	Audio-navigation unit connector A (24P): disconnected
  Test point 1	Audio-navigation unit connector A (24P) No. 24
  Test point 2	Body ground

  Is there battery voltage?

  YES 

  The GND wire is OK. Go to step 5.

  NO 

  Repair an open in the wire between the No. B19 (7.5 A) fuse in the under-dash fuse/relay box and the audio-navigation unit.

• 5. Open wire check (GND line):

  - 1. Measure the voltage between test points 1 and 2.

  Test condition	Vehicle ON mode
  Test point 1	Audio-navigation unit connector A (24P) No. 1
  Test point 2	Body ground

  Is there less than 0.2 V?

  YES 

  Replace the audio-navigation unit .

  NO 

  Repair an open in the wire between the audio-navigation unit and body ground (G503).