lexusscturbo

iTrader: (12)

Your impedance is lost along the way somewhere...Speakers use 4..OEM sub is 2OHM's.
Something's going to give..I doubt it'll be the Kenwood HU..

twong82

since the stock sub amp is used, you don't have to worry about ohms...a sub that is 2 ohms needs an amp that can output at 2 ohms...it has nothing to do with the headunit...everything should be ok...

supralative

iTrader: (4)

Just finished up my install. Everything works as twong82 said.
Question for the guys that used the Crutchfield harness. Did you guys hook up the amp turn on wire from the Crutchfield harness to the amp turn on wire of the aftermarket head unit harness?

Sup2jzgte

twong82 did you cut the RCA's on the MEtra harness and hardwire into the Headunit or did you keep the RCA ends on?

supralative

iTrader: (4)

Hopefully I can help you.
I didnt cut any harness and hardwire. Just used the supplied Crutchfield harness/adaptor...spliced some power, ign, ground, and turn on wires to the aftermarket headunit harness and plugged it all in. Had to use a ground loop isolator for my stuff thugh. Bought a RCA to speaker wire adaptor to get the sub working. I just plugged in the end leads of the adaptor into the factory plug and taped them together.

twong82

I did not cut anything from the Metra harness.

Sup2jzgte

So you just used the RCA's to your Head unit? Did you get any alternator whine?

howiedoit

iTrader: (9)

Same question for me. I'm getting alternator whine after installing my Kenwood DNX5120 with the Crutchfield harness. I'm using the RCA's to the headunit. Everything else is factory stock. I got the factory sub to work like you described...I tapped into those 2 wires, but I get the whine whether or not I hook into the factory sub.

Do I need to bypass the factory amp to get rid of the whine?

Sup2jzgte

From reading many posts on here some people cut the ends off of the RCA's and wire them to the positive and negative speaker lines on the head unit, this seems to get rid of the whining. Now I could be mistaken on this because I have read some many different ways of hooking a radio up to this car that I could have confused a few threads or mixed threads up, that is why I'm still researching.

howiedoit

iTrader: (9)

I just installed my headunit. I bypassed the factory amp, which is underneath the CD changer in the trunk because I was getting alternator whine. I tapped into the wires that the OP posted and connected it to my headunit through an RCA and everything works (all speakers and sub) with no more whine!

Thanks OP!

raine

iTrader: (7)

tried this, didn't work.

Using the intellexual diagram for the sub amp, I was going to run wire from the head unit straight to the amp itself, but weird thing: The wiring harness that plugs into the sub amp, it does not have all 10 pins! Either pin 1 (or pin 4 depending on how you look at the diagram) does not even have a wire running through it from the harness - yet with the stock head unit, my sub was working fine. Any thoughts/ideas?

Sup2jzgte

I did this with my craptastic Avic 700Bt and I to could not get the sub to work at all

I did run all new speaker wires and bypassed the amp in the trunk, but I thought the sub amp would still work, I guess not

2turbo1sup

iTrader: (2)

^ x2 with the same headunit. Im going to have to look into the wiring diagrams again to find a fix. i'll keep you posted

Sup2jzgte

The only thing I can think of is running the sub amp turn on wire directly to the turn on from the headunit and running the rca to bare wire from the sub amp to the head unit. The way I understand it is the sub amp turns on via a pulse from the other amp, so since we bypassed the other amp it is not being turned on therefore the sub amp is not getting power.

I really have not had a chance to try it as of yet............no time lol

2turbo1sup

iTrader: (2)

Hrmm, i'll try to wire the sub directly the sub out with new wires and see if that works.

Im looking at the installation manual and if you check page 10, you can wire the sub directly to the rear speaker wires. There's also a note: "When using a subwoofer of 70W (2ohms), be sure to connect V & V/b leads. Do not connect anything with the G & G/B leads". I have no idea what the specs are on the stock sub, so i'd appreciate if someone here can enlighten me