Old school aftermarket deck w/ premium sound

[kellen302]

I decided to separate this from my previous thread on the OE Premium Sound head unit and wiring to make it easier for future searches. I have a 1986ish Kenwood KRC-434 I bought fully refurbished off of a guy on Ebay. I've got the appropriate Metra adapter to go to the factory in dash plugs. Everything powers up, but I get no sound out of any speakers aside from the slightest hiss out of the front right (front left not plugged in currently). Looking at the wiring diagram for the Kenwood deck, it uses a common ground between front and rear speakers on the same side; ie, front right and rear right have a bridged negative wire on the head unit pigtail.

I sent it back to the seller and he confirmed that the head unit was working fine so it is on my end. I get sound out of the front channel through the amp now on the factory head unit. Is this no sound out of the new head unit a result of mixing two types of common ground? I would assume I could at least get rear sound because they do not go through the amp.

Any tips? I can post diagrams if that would help as well

[gadget73]

Do you have an amp in the trunk? Is it bypassed? If so, how exactly? The premium sound cars came with an amp, some are only amplified on the front speakers, some are on all 4 speakers.

What you really need is the EVTM and a flashlight. Have a look at what is connected where and compare the wire colors to what they should be.

[kellen302]

I have the football 2 channel amp in the back and I've gone through all of the wiring with my EVTM and shop manual to return it to stock. The PO had bypassed everything.
Currently a stock premium sound head unit plays sound fine through all channs, I went to the Kenwood unit because it looks cooler and has a functional cassette deck. My adventure with the stock system is in the linked thread below.

http://www.grandmarq.net/vb/showthread.php?56655-Refurbishing-Factory-Premium-Sound

[gadget73]

yeah, thats not going to play well with the Kenny. You should be able to get sound out of the rear speakers but possibly its shorting something out because the amp is there. Try unplugging it and see if that makes the rear speakers work.

[Mainemantom]

Maybe I am missing something but when I changed my stereos to Kenwood and replaced all speakers, I bought a "by pass harness" for the amp. Even bought a direct fit harness to the new stereo. Everything works perfect on both cars now.

[gadget73]

depends what year and which amp, but the older ones had 3 wires heading to the amp for the front speakers, and more modern stereos need 4, 2 per-speaker. The original premium setup had a common ground and a left and right wire. rear speakers were just 4 wires radio to speaker, no fuss or nonsense. Later stuff had 2 wires per-speaker so it wasn't any big deal to just bypass the amp, essentially the input connects to the output and you're set. No way of going from 3 to 4, and the radios generally will not work if you short the two grounds together.

basically the way you deal with that is to unplug the amp, use the original wires from radio to rear speakers, and run new wires to the dash speakers. Leave the original harness connected to the dash speakers as well and it will feed the door speakers. Just make sure the amp in the trunk isn't connected and it will work fine.

[kellen302]

SUCCESS! Not sure if anyone wants to put this and the other thread I have together for information on these transitional Premium Sound packages or not.
I used the Scosche Floating Ground Adapter and only wired it to the front channels (into the amp) and the front outputs from the receiver, plus the chassis ground from Floating Ground Adapter to radio/chassis ground. I used the Metra 70-1772 Adapter harness and put the floating ground adapter in between the speaker plug and the receiver. Left unused wires from the ground adapter covered with heat shrink. There is enough room to get all of this back in the dash if you are careful and do some bundling of your wires.
The receiver was mounted using the Metra 99-5700 DIN Adapter Kit. Use the one that looks like a DIN radio mounting pattern for DIN radios obviously. You will have to cut the unused tabs off, but they are all hidden. I have not had a chance to get the dash fascia back on yet, but it looks like it will fit. I had to do a little clearancing to get the pull out handle to move freely but that is not an issue for most radios.