99 Volvo 770 Codes and issues please help

[zack.basic]

Hello everyone
I just purchased a 99 Volvo 770 with a Detroit 12.7 L and a 13 spd fuller nice looking and runing truck but I just figured out how to use the #### diagnostic system and found a few codes on it I would like to know what the codes really mean and if there is a way to erase the codes so I can see if they come back up or if maybe the codes have been fixed , Please thank you
so the codes then
1 engine % throttle pedal voltage shorted low inactive count 1
2 engine PID voltage shorted high inactive count 12
3 engine SID 239 voltage shorted high inactive count 12
4 engine SID 51 voltage shorted high inactive count 8
5 Airbag not responding
6 brakes ABS snsr axle 2 l data valid but low inactive count 127
7 brakes ABS snsr axle 2 l abnormal change rate inactive count 25

the only other issue I have is the marker lights the previous owner installed go on and off but I checked the wiring and its all there and in its not shorting out or anything the lights just go on and off randomly every 20 min and come back after 2 min don't know what that is does anybody know

[ohio_redneck75]

the light issue may be the breaker is getting week.

[zack.basic]

oh OK thank you i ll check that out
does anybody know anything about those codes