Audio System Symptom Troubleshooting - Audio unit power switch will not turn on (No audio information display and no sound) (With Normal Audio)

Audio unit power switch will not turn on (No audio information display and no sound) 

NOTE: 

• Check the vehicle 12 volt battery condition first .
• Check the connectors for poor connections or loose terminals.

• 1. Problem verification:

  - 1. Turn the vehicle to the ON mode.

  - 2. Press the POWER button on to see if the audio unit turns on.

  Does the audio system operate properly, and does the audio sound normal?

  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. B19 (7.5 A)
  Location	Under-dash fuse/relay box

  Fuse	No. B25 (10 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 B19 (7.5 A) fuse and/or the B25 (10 A) fuse circuits.

• 3. Open wire check (+B AUDIO line):

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

  Test condition	Vehicle OFF (LOCK) mode
  Test point 1	Audio unit connector A (24P) No. 3 - Refer to: Audio Unit Connector for Inputs and Outputs(With Display Audio) Audio Unit Connector for Inputs and Outputs(With Normal Audio)
  Test point 2	Body ground

  Is there battery voltage?

  YES 

  The +B AUDIO wire is OK. Go to step 4.

  NO 

  Repair an open in the wire between the No. B25 (10 A) fuse in the under-dash fuse/relay box and the audio 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
  Test point 1	Audio unit connector A (24P) No. 24 - Refer to: Audio Unit Connector for Inputs and Outputs(With Display Audio) Audio Unit Connector for Inputs and Outputs(With Normal Audio)
  Test point 2	Body ground

  Is there battery voltage?

  YES 

  The ACC 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 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 unit connector A (24P) No. 1 - Refer to: Audio Unit Connector for Inputs and Outputs(With Display Audio) Audio Unit Connector for Inputs and Outputs(With Normal Audio)
  Test point 2	Body ground

  Is there less than 0.2 V?

  YES 

  Replace the audio unit - Refer to: Audio Unit Removal and Installation(With Display Audio)Audio Unit Removal and Installation(With Normal Audio) .

  NO 

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