I own a 1998 audi a4, 2.8Q. Any way, got the wiring harness 2 swap out my plain jane audi delta cassette deck for an alpine cda-9856 (couple years old but better than a cassette deck). After all of the wiring was matched up I plugged it in and can't get any sound out of the rear speakers. I even hard wired the output of the alpine straight to the LR and RR sections of the "Line out" harness (the little yellow one). Just wondering how i can get the rear speakers to work. am i grounding them correctly with the 2 brown wires from the same harness or not (i was told these leads go to an external amp specifically for the rear speakers)? Would like to get my stock rear speakers to work w/o having to buy an amp and aftermarkets and having to run RCA's and power cords 2 the trunk. A big Thanks 2 anyone that can help!!

 

The only quick way I found when swapping mine out because I had the same issue, I had to buy a deck with 4 rca outputs on the back. Mine had the bose as well.

 

Are you trying to use the stock amp? Sounds like the amp is not getting power. I have a Jensen and just bypassed the stock amp.