Radio Dead After Jump Start - Symphony II

[Michael.acbf]

Hi,


So I drive an Audi A4 2002 B6 and I am new to this.
So the short story of mine was this.


My car was having problems to start I could listen to crank noises and the car wouldn't start but all electronics was working including the radio, so I jump started the car, and at that moment the car started but Radio dead no power at all, but later when I turned off the car it wouldn't start the car, and then I saw that the borne of the battery was getting lose, so I put it right and all this time my battery was ok with no problems and I didn't need to jump start the car.

But ever since I jump started the car the Radio is still dead and I searched everywhere for solutions, and I replaced both fuses in the car but I saw that the bad fuse was the one behind the unit because after that I can even listen to the sound of Disks switching but still no power no SAFE nothing.

Can someone help me? I don't know what to do next

[Nollywood]

If you have access to VCDS, or know someone who has, you can actually scan the audio unit. Though if it doesn't power up, it most likely won't connect with any diagnostic equipment.

It's possible the head unit has tripped, beyond just a fuse. Did you by any chance accidentally put the jumper cables on the wrong way, initially?

[Michael.acbf]

Hi Nollywood,


Thank you for your reply, I don't own a VCDS but yes since the Radio doesn't get power at all but I will still try, well yes when my friend was putting the jumpers in my car he mismatched and there was sparks for a second then he corrected, I have to say that after that the fuel gauge was showing empty but then I just took off the fuse and reconnected and the fuel gauge was ok but the Radio still dead, but I will still consider checking with VCDS, do you have any other thing that I can test also?

Thank you for your reply

[Nollywood]

I would say the radio is toast.

It could have been worse, reverse polarity can often fry your ABS modul, ECM and instrument cluster. Just get a replacement radio, and count your lucky stars.

[Luxus Panzer]

I would say the radio is toast.

It could have been worse, reverse polarity can often fry your ABS modul, ECM and instrument cluster. Just get a replacement radio, and count your lucky stars.

Why would they not put a simple diode (1 way resistor) in line on our cars ?

[ErikG]

Nolly - Good call on the reverse polarity connection. More than likely found the cause.

Luxus - They do but there are limitations, and your example is used extensively. Had they just connected a battery in reverse everything may have been ok, but by connecting 2 batteries together and directly shorting them together can create voltage and current spikes that overwhelm the reverse polarity protection. There are more robust solutions that are now coming into favor that can handle all sorts of abuse using MOSFETs and other stuff. Source: am EE

Michael - consider yourself very lucky. This simple error could have really done some damage. If a fear of mine when i jump a car. I triple check the connections lol.

[Michael.acbf]

Hi All,

Thank You all for your kind answers I guess I should triple check from now on, and consider myself very lucky for this time.

However my dealer is charging a over price for my Radio, can someone tell me where can I buy online an Audi Symphony to replace my toasted one?

Best Regards

[Kevin C]

Why would they not put a simple diode (1 way resistor) in line on our cars ?

It might... But it may not be enough. It easily could have been the CAN bus line that got damaged. Communication busses are not as easy to protect and their protection may have been compromised from previous incidents. Also, protection devices can get damaged over time. A loose battery terminal or a battery with a bad cell can cause severe transients in your electrical system (google "Load Dump"). You may not get an immediate total failure but the protection circuits may get taken out or partially damaged.

Fun Read:

http://www.ti.com/lit/an/snva717/snva717.pdf

[old guy]

Hi All,

Thank You all for your kind answers I guess I should triple check from now on, and consider myself very lucky for this time.

However my dealer is charging a over price for my Radio, can someone tell me where can I buy online an Audi Symphony to replace my toasted one?

Best Regards

Clicky click®