Had a Panasonic Radio in my truck. removed that for an old Becker Radio. The wires are named so that there should no big problems to change the Radio.
But one issue: I found three wires but are not sure how to connect them.
A yellow one ist named "Battery 15A", a red one "ACC" and a black one without any clue.
How do I do things right? The ISO Connector can't be used for my old Radio, all wires will have their own place...

Thank your for any advices
Gerhard

 

black is almost always ground.
Red is battery hot.
Yellow is hot with ignition or accessories on.

 

No offense but I think you may have reversed the red and yellow here - yellow seems to be the constant 12V and red is the switched 12V.

 

Yellow goes to the battery positive terminal, through a 15 amp fuse, and red goes to a 12V+ source which is only live when you turn the key. Black will be ground.

Blue might be an output for a power antenna or auxiliary amplifier, if it's not a speaker wire.

 

I have wired quite a few stereos and this is pretty much the standard. It might be blue or blue with a white stripe, but it is used as a signal wire to turn on a power antenna or amplifier. I have never seen blue used for a speaker. Speakers are usually grey (right front), white (left front), purple (rear right), and green (rear left). Each speaker has two wires- "+" is the solid color wire and "-" is the same color with a black stripe.

The only other common color I have seen is orange(usually with a white stripe). That is rarely used, but connects to the dimmer for your dash lights so your stereo faceplate dims accordingly.

 

Yes, speakers are grey, white, purple and green.
Thanks for all the advices