JVC KD-R491 Schematic Diagrams page 42

4.5 DC Error Information Mode
In during power off, pressing and holding [DISP] key and [] key, then power on the +B power supply.
4.5.1 Default status immediately after the mode activation
It shall be same as normal activation.
4.5.2 Mode content
Syscon shall display the following information after entering this mode.
Display content
D C E R R
D C O K
Item Operation
DC ERR1display

DC ERR1 clear 
DC ERR2 display

DC ERR2 clear 
4.6 DOP Setup Mode
Pressing and holding [VOLUME] key, then press [DISP] key for 7 seconds.
(Starting to press [VOLUME] key and [DISP] key at the same time can not be entered into the mode)
4.6.1 DOP Setup Mode Common Setting
Common settings for all car makers are as follows:
Demo: No demo animation
Remove all DEMO related items
Power on animation: Show carmaker's name
Only opening animation will show "Car maker's name"
4.6.2 EEPROM DOP Read Error Display
In the case of an EEPROM read error or EEPROM DOP read error, the unit will behave accordingly.
(1) No Power on animation
(2) No Demo animation
(3) Demo removed in setup menu
(4) Color settings set to default
(5) Serial number display replaced by "SN @@@@@@@@"
When DC error is detected
When DC error is not detected
Display content
D C 1 E R R
D C 1 O K
D C 1 O K
D C 2 #
D C 2 0
(No.MA665<Rev.001>)23/33
Details
Details
When wrong connection & DC error in other detec-
tion duration is detected
When wrong connection & DC error in other detec-
tion duration is not detected
Clear detection information when wrong connection
& DC error in other detection duration is displayed.
(Clear data flash)
Display detecting number of times in capacitor leak-
age detection duration
#: 0 to 4
Clear number of times for detection information in
capacitor leakage detection duration. (Clear data
flash)