PreAmp Leads from Harness?


LVC Member
Jan 24, 2021
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West Virginia, United States
Hey all, im the new owner of a 2005 ls, v6 5spd auto, base model, from what i can tell.

Forcusing on the stereo situation... its an original cd/tape combo with original door speakers, and thats it.

Im wondering if all models are pre wired for the 'under tray' subwoofer system. If so, is there a way to tap preamp signal, and remote lead, or am i in dreamland? :) since the battery is already in the rear, it would be nice to avoid running rca and remote lines.

I have a few things already. One is a wiring harness. It comes with a secomd harness with rca outputs. Also a 2din mounding kit, and plan to upgrade to an android head unit sooner than later.

For now, the sub amp combo woll be what i already have setting around, which is a 10" apline s type and mono alpine vpower 220w rms @ 4ohm. I have both sealed and ported truck boxes for it, but leaning toward using the sealed box.

Ultimately tho, the current setup is just a beta test to establish all the wiring needs. Im thinking that i will swap it out for an under-seat powered sub. But mount it under the rear deck in the trunk.

Rockville has an 8" model that measures about 11.5 x 8.5 x 3 inches that sells for around $100, and gets great reviews (model SS8P).

Ive already removed the cover where the factory sub pack would fit and pulled some measurements. Theres a void between the cover and metal rear deck thats about 3" in the shallow areas and 4" in the deep spots. I think i can mount that Rockville up under that cover, in the deep area, and have it entirely hidden, and not lose any trunk space... both of which are important to my needs.

Rockville sells another 8 inch model (RW8CA) with more power, but a square box. Its a hair slimmer than the other one, but i do t thing it would fit under the cover as well, althought it may, since its less than the minimum ~3 inch gap. Theres identical 10 inch models also but i havent checked them out cause im really wanting the 8 for tighter punch over boom and rattle of a larger sub.

Focusing back on the wiring...

I saw somewhere, a harness that i think connected to the factory socket, and had amp leads or something? Maybe im mixing this one up with a different car tho. ?? (Edit: found a screenshot. See below)
(motorcraft pn WPT667)

Anyway, attached are some pics of the 'void' or 'gap' area beneath the rear panel cover, and of the connectors i found on the left side wall of the trunk, behind the trunk liner.

For reference, there are a couple screenshots of the (i think) original/compatible sub setup, from an s type jag tho. Looks like a jumper harness runs between the amp and the car harness. Is this the same/compatible with the Lincolns? Plug n play?

Aaaanyway, any input on thiese matters is greatly appreciated. Great forum here btw.






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Your on the right route, my ls came originally with the rear sub and amp but was long gone by the time I came upon it, I tried for a while to pin out the proper lines to have a factory style amp. Only success I had was using the old harness for a remote turn on but even that was problematic as the o/e unit used a 7v amp trigger and caused my amps to "pop" on startup. As for the RCA's in the harness you got they are for the front center mounted "tweeters" from the old factory system so you probably don't have them. In other models the garnet fits it hooks in to other amps but not our car. Personal suggestion would be to take out the passenger seat and pull up the carpet and run a remote wire and RCA's to the back and get a line out converter if u want to use the stock head unit ..but that's my 2¢
Thanks for the reply

I defintiely could have pulled the seat and ran some lines by now! Haha! And if it wasnt for the challenge of just making it work, i probably would have by now. Well, that, and that im still using the original head unit, and a new head unit is not top of the list right now (have an older eonon touchscreen but its too big to fit the 2din kit. Go figure.)

My thinking is that the rear harness, if the harness is prewired for higher trims, should have a power or remote, and at least speaker level inputs. Has to be getting a signal some how. Ive seen mention if people talking about using that wpt667 harness to connect stereo gear in various ford models.. and it does look like it would fit that rear-left harness. Im pretty sure that the same connector that the amp harness would hook up for the rear sub option, if equipped. But finding specifics for my car hasnt been fruitful. My thinking is that i may be able to use that wpt667 to connect remote lead (even if always on with the switch) and speaker level or rca input signals.

I already have a speaker line > rca box that i could use. Can also get a step up converter for a few bucks on ebay and use that to boost remote voltage up to 12v. So all that is managable as long as there are some audio and power sources i can tap into back in the trunk.

Just for clarity, im attaching two pics again. One is the cars harness left rear trunk area, the other is the pigtail im thinkkng might fit it, wpt667


So at this point, i guess im needing confirmation whether or not that connector in the trunk is actually for the factory amp and sub option?

And if anybody has any info on that 667 pigtail, if it fits, etc, thatd be cool.

Or anything else .. im open to suggestions. Just thought it was do-able, and would be a challenging project to take on.
First off, you have the base radio, and I'm pretty sure it does not have any output for the subs. Pull the radio and look for 8-pin connector 290d. If it's not there and plugged into the back of the radio, then no subs from your factory radio.

Secondly, the factory sub signal is a mono differential line level output, not speaker level. If you are going aftermarket, you would be better off to run a new normal (ground referenced, not differential) RCA line level cable. The differential sub signal uses a twisted pair of wires surrounded by a shield.

That connector in the trunk is C465. Pin-out is:
2 - Blue/red - Constant battery power, 20A max
4 - shield
5 - Black/blue - Ground
6 - Yellow/red - Amp turn on signal*
9 - Gray/red - line level sub signal, differential -
10 - White/red - line level sub signal, differential +

*: This is actually a two way signal. On/off control to the sub amp, and diagnostic info back from the sub amp. To correctly drive this signal from aftermarket, you must use a current limit resistor (around 1K is good) to prevent overloading the amp's diagnostic signal. Using a 5V regulator is not the correct way to do this. While it usually eliminates the turn-on thump, it still stresses the amp. A resistor eliminates the stress to the amp when it tries to drive the diagnostic signal.
Thanks thats what i was needing to know. Im pretty sure its a base radio package also.

Side question.. ive seen some head units say they wheel control programming. Does that usually work out of the box if i run thru the setup, or is there another harness or anything i need to adapt wheel controls to a new HU? Are there some brands known to work better with this vehicle than others, or anything i should consider.

I found out that its common for the china double din units to be different dimensions than standard aftermarket 2din units. Supposedly they fit factory dash holes pretty good, but a mounting kit needs to be modified to fit.


From the sound of things, the best option id have without changing the head unit would be to back probe the harness behind the radio to connect the speaker level to rca box and a remote lead. That way the amp wiring would already be in the dash when i get a new head unit, and i coukd just remove the rca box at that time. Option B would be to take off two door panels in order to tap the speaker lines, and run a mile of wire from each to the trunk or wherever (its the 4 speaker setup, one in each door panel).

Even if i upgraded the head unit first, it sounds like the idea of tapping the trunk sub harness would be a lot if hassle and still not be optimal even if i rigged something up, so .. scratch that.

That base radio sucks really bad tho, but id rather save up to get a decent head unit over one of those $100 china jobs... for sound quality and fitment purposes. So ill prob bite the bullet and do the rca box and run wires to the trunk for now.

I have a pair of 1 inch add -on tweeters in the bin also, so i figure i can throw them in the A pillar or some place. Between the sub and tweets, it should fill the spectrum a lot better. Then i can swap out the HU later on and be done with it. Basically plug n play at that point.

Pictured is the harness i have for it. The small one has rca-out to harness connector, but am i correct that i wont need to use it, since i wont be connecting the new head unit to any premium sound options? Instead i would connect my aftermarket rca lines to the head unit, as usual with an aftermarket stereo install, right?



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