Aftermarket Radio Head Unit won't power up

03 A3 8l

Registered User
Jun 10, 2019
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Hello everyone,

I have checked other threads and watched as many youtube tutorials as I could find and was still unable to find the help I need.

I recently bought an 01/2003 Audi A3 8l, which sadly only had a cassette player in it, of course I wanted to upgrade to one with at least a CD-Player and an AUX connector. Thus I went online, got carried away, and found myself a Kenwood KDC-BT530U (stupid me thinking it would be a simple plug and play, which it obviously was not).

So I did my research and found out i need an adapter in order for the rear speakers and sub to work, so I went ahead and bought an adapter off Amazon (thinking ok well it might be 40 bucks more than I wanted to spend but at least now it will work). Clearly it did not...Sooo now im here asking for some help because I am clearly not cut out for this whole radio installation thing.

The Kenwood system has at no point during the installation powered up (could this mean its broken?)
I have probed the connectors(car side) with a Multimeter and some have power, others do not (normal im guessing).
I did read that I need an ignition live switch from the fuse box, however I don't know if I did it right, but it seemed like none of the fuses I could use went on with the ignition and off again when I pulled the key. (does anyone know exactly which fuse I can use with certainty or is there another way around using the fuse box?)

Happy to answer any further questions.

I appreciate any and all help.

Kind regards,
My ignition live switch is connected to relay switch 53 (see link provided by tcg). Also the wiring harness needs to be swapped for positive and negative (refer to “Connecting the ISO connectors on some VW/Audi automobiles”)

Check and check again, wiring connections for positive and negative connections using a multi-meter, before connecting the head unit.