Ground Noise after Avic D3 Install

Bought an AVIC-D3 off of another forum. It was prewired for his B5 A4. I have installed it into my C5 A6. Seem to have a grounding issue. I hear engine noise through the radio and have double checked the wiring as well as added a ground with no luck. Any suggestions? This installed in Symphony II Vehicle with Bose setup. Seems like the grounding issue has something to do with the RCA's. Any advise?

No replies? No one has any answers?

No replies? No one has any answers?

I have the same problem in my 1999 Toyota Landcruiser with factory amp. Tried multiple different grounding points. Probably related to the RCAs. While I haven't bought it yet, I'm pretty sure I'm going to buy a ground loop isolator. A 4-channel version can be had for only $8 + S/H at Monoprice dot com. Saw something similar at Fry's and I think it was $25-30. Didn't inspect further to see if it was wired into the ground line, or connected in between the RCAs lines like the Monoprice one.

i believe you need to ground the rca's to the radio. i had same promblem with mines and its all good now

I have the same problem after installing a D3 in my Boxster.

The RCA's are remote from the unit, I did try running soldering a 6" cable from each of the RCA's back to the head unit but no difference. Also re-grounded from good earth points and it also made no difference whatsoever. I have used shielded RCA's and the problem is definitely the head unit or the RCA's - the amps and the speaker cable is fine.

Am at my wits end, time for a ground loop isolator!