Radio has stopped working, but the panel on the radio stays lit in red when the car is turned off,( the little light items on the radio which would normally go on when the lights are turned on. it is an audi radio) It does not say 'safe' on the display. Not sure if I have the code if it is the fuse, its my sons car and not here at the moment.

Before you start replacing parts ,need a little more information . Maybe able to save you some time an money . Does the horn work when you push the horn button , does the air bag light stay lit in the instrument cluster ? The button lights for the bottons on the steering wheel are lit by the BCM - body control module . Interior Lamps Dimming
The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and incandescent lamps.
When the ignition switch is turned to the RUN position, the radio's vacuum fluorescent (VF) displays turn on at maximum brightness. When the park lamps are on, all incandescent back lighting turn on at the dimming level indicated by the I/P dimmer switch. At the same time all vacuum fluorescent (VF) displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the BCM. When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.
The following switches and components have back lighting when the park lamps are on:
• The instrument panel cluster (IPC)
• Radio, front and rear
• Window and heated seat switches
• Garage door opener switch
• Selectable ride switch
• Roof beacon switch
• Power take off (PTO) switch
• Headlamp leveling switch
• Rear wheel steering mode select switch
• HVAC control assembly
• Headlamp and panel dimmer switch
• Transfer case shift control switch
• PSIR disable switch
• PRNDL lamps
• Traction control switch
• Steering wheel control switches
• Fog lamp switches

Could be the clock spring inside the steering coulmn ,under the steering wheel if horn doesn't work ,air bag light lit etc...

The electronic power steering (EPS) Warning Light is located on the instrument panel. This light illuminates when the EPS is malfunctioning. When this light is lit, your steering may be a little heavier, and you should schedule an inspection as soon as possible. Tip The EPS Warning Light briefly illuminates when the car is first turned on. The light is only a problem if it stays lit for an extended period.

The electronic power steering (EPS) Warning Light is located on the instrument panel. This light illuminates when the EPS is malfunctioning. When this light is lit, your steering may be a little heavier, and you should schedule an inspection as soon as possible.

THE CANCEL COMES FROM THE LIGHTING CIRCUIT UPON OPENING THE DRIVERS DOOR. THE DOOR SWITCH MAY BE BROKEN

replace IC of car door lock... this is a little black box inside the steering wheel cover

My audi a4 2002 3.0 quattro radio just stop working with the red light that stay on. It does'nt display "SAFE" , so I don't think that is lock. Please help

Usually the security light means it can't read the chip in the key.. the little black chip at the base of the key.
Try using a spare key

Check the fuse for those items that don't work.

CHECK THE FLASHER

if brakes work ok leave well alone ,this sounds like an electrical fault that big money to repair.At the end of the day the brakes are failsafe manually operated

stop slamming your doors so hard you are messing up the sensors!