Acura 3.5 RL Manual page 1341

UNIT CHECK
DISP (DISPLAY UNIT)
RADIO (AUDIO UNIT)
NAVI ECU (NAVIGATION UNIT)
Touch the item you want to check, and the check starts.
When the connection is NG
Check for an open or short in the communication line. If the line is OK,
replace the display unit.
When the ROM or RAM is NG
Replace the display unit.
When the connection is NG
Check for an open or short in the communication line. If the line is OK,
replace the audio unit.
When the ROM or RAM is NG
Replace the audio unit.
When an item other than GPS is NG
Replace the navigation unit.
When GPS is NG
Replace the navigation unit.
When GPS is NG (ANT)
Check the GPS antenna for proper connection. If the connection is OK,
replace the GPS antenna.