Hi,
I have a 1999 Volvo s70 t5 with the SC-901 setup but not dolby digital. I recently purchased a Alpine CDA-9884 Head unit and would like to install it on my car. To start off 1)Will all 8 of my speakers work 2) I have the factory amp thing pluged into my deck and the "sub" cabel pluged into my deck so to my understanding if i unplug those my rear 8" wont work and my speakers will not work as they go from amplifire.So my question is how do i install it so i have it work fully!If i just buy the wiring harness will that work or do i need anything eles. Thanks

 

Well after talking with alot of people in various stores everyone to date told me i have to Rewire every speaker.Well i though surely it cant be like that thats dumb! So i decided to investigate! I took out my stock SC-901 and looked at the harness, pluged in my deck and crap! Nothing!!! just power on my deck no sound So then i decide to follow the harness down and found a piece of yellowish foam and decided to look it it! WOW it looks exactly like the harness i just disatached from my old deck.Well i decide to hook up my new deck through this and guess what IT WORKS!!!!! The only thing that doesnt work are my door speakers as i think 1)i wired something wrong B)they are usinfg a diff plug wich might be a problem. Nevertheless for anyone who is trying to install a head unit there is a ISO plug hidden in some yellow foam, this is the plug that makes everything work

 

it could very well be that the speakers that aren't working are powered by an outboard amp while the speakers that *are* working are powered by the stock deck's amp. so you may have to trace some wires.

sorry i can't be more help but i know very little about the volvo's stock sound system. if you need help with aftermarket... i can help you with that :-)