Audio System Symptom Troubleshooting - Audio unit button illumination does not work (without navigation system)

Audio unit button illumination does not work (without navigation system)
NOTE:
  • Check the vehicle battery condition first.
  • Check the connectors for poor connections or loose terminals.
  1. Turn the ignition switch to ON (II).
  1. Turn the combination lighting switch to the parking light position.
  1. Check the illumination of the audio unit buttons.
Are the buttons illuminated?
YES -
Intermittent problem; the audio unit is OK at this time. Check for loose or poor connections at audio unit connector A (24P).■
NO -
Go to Step 4 .
  1. Check the illumination of several other buttons not related to the audio system.
Are the buttons illuminated?
YES -
Go to Step 5 .
NO -
Troubleshoot the interior lights. Start by checking the No. 6 (7.5 A) fuse in the passenger's under-dash fuse/relay box. If the fuse is OK, check for an open in the wire between the passenger's under-dash fuse/relay box and audio unit.■
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect audio unit connector A (24P).
    NOTE: Eject all the CDs before removing the audio unit and CD changer to prevent damaging the CD player's load mechanism.
  1. Disconnect the gauge control module 32P connector.
  1. Check for continuity between audio unit connector A (24P) terminal No. 1 and the gauge control module 32P connector terminal No. 2.
Is there continuity?
YES -
Go to Step 9 .
NO -
Repair open in the wire between the gauge control module and the audio unit.■
  1. Turn the ignition switch to ON (II).