I have 2004 Crossfire coupe with a factory amp and i wanted to upgrade to a new head unit that provided me iPod controls as well as Pandora music control.

I went for the Kenwood KDC-BT952HD receiver which has RCA outputs for front, rear, and subwoofer. I also purchased the Metra wiring harness with RCA connections (item# 120701786).

I removed the old unit and connected the new one but there is no sound coming from the speakers (not even the "beep" that occurs when switching sources). I tried turning off bypassing DSP on the HU but still no sound.

I'm using the P. Cont wire (Power contol) from the HU to Blue/White amp turn on lead from the harness. Is this correct. I'm hoping that I don't have to run the Sub out on the HU directly to the factory amp.

I have installed quite a few HU's and this is a pain in the @$$.

 

On my harness the blue remote turn on wire needed to be moved to the spot next to it. Sorry I dont recall what color it should power, but you should be able to find it in wiring diagrams.

 

Do you mean you move the wire located on the wiring harness plug going to the car or the wiring from the HU? A little confused.

 

The blue wire in my adapter actually was loose in the package. I used this to locate which pin in the oem harness it needed inserted to so it would match up when plugged together .. click the picture, then at the bottom click enlarge.. or get magnifying glass out.. LOL.

Edit:
Not sure about the metra.. but there is this tidbit on the scosche

The constant and switched power wires are flipped, so you will need to connect the Red wire of the Scosche harness to the Yellow wire of the aftermarket one and the Yellow wire of the Scosche harness to the Red wire of the aftermarket harness. The Blue antenna wire on the Scosche unit is actually the remote wire. Attach the Blue-White wire from the aftermarket harness to the Blue wire on the Scosche harness.

 

Can you post the HU wire diagram so we can see what the options are?

Thanks - RL

 

The above image didn't clarify where the remote turn on from the new HU needs to locate in the adapter?

 

Miata - are you thinking he needs to move a wire in the adapter harness to make a connection to the amp power wire for the car wiring?

 

Exactly.. the pic shows location on OEM HU which you can correlate to the OEM plug- insert wire into adapter to match up.. like I said mine was laying in the adapter package for user to put where required in the adapter plug.

 

Two things to check.

1. Make certian that you are locating the blue wire correctly in the adapter harness to turn on the amlifier.
2. Make sure you connect the radio's AMP trigger wire and not the power ant wire. On many HU today these are now two differnt connections one is typically blue, the other blue with a white trace.

 

I attached the wiring diagram image for the kenwood HU. I'm using the Metra wiring harness.

Metra Part # 70-1786 | Land Rover wire harness | Metra Online

On the Metra the red/yellow wires are not switched (I tried flip flopping them and each time I powered off the car the HU would reset to Demo mode).

I'm connecting the P. Cont from the Kenwood to the Blue/White Amp Turn On.

 

If you are using the RCA preamp out of the radio with the factory amp you are going to have a challenge. The factory amplifier calls for a high level input aka speaker level from the head unit amp.

 

So I should have purchased the Scosche harness instead? Why the heck would Crutchfield suggest to me the Metra if the factory amp is a issue?

 

Preamp Voltage 4 volts
Based on this.. and several users input after their installs this way..

He's good to go there..

 

Did you look at the image I posted? Just go color blind and match hu labeled wires to adapter so when plugged in to OEM harness they will match up..

Hmm..it opened last night.. lets try this again..

https://www.crossfireforum.org/forum...out-83606.html

Holding oem harness in hand.. looking at pins.. top row 3rd position from left is amp turn on location (held as if ready to plug back into stock radio)

 

The brand does not matter. The harness is a generic euro harness and as such can fit a ton of cars from vw to mercedes and more. There is no need for RCA connections for what you are doing. What you purchased is an "Amp Intergrations Harness" used for adding an aftermarket amplifiers to be connected to OEM head units. In this case the old mercedes becker head units used to have a preamp section that could be tapped into.

If you go with Metra look for the generic european/bosch harness or schosche has one too which might be identified as a vw harness. About the only thing you may need to repin is the amp turn on

 

Ah, that image is a lot better . I'll verify A5 (Amp/Power Ant) is going to the Blue/White wire on the kenwood side).

If I can't get the Metra to work I'll try the Scosche VW01B (hopefully my local Best Buy has it).

I'm leaving work shortly so I'll post my result later tonight.

Thanks.

 

Yeah it "clicky-linky" last night.. totally useless today though..lol.

Got to thinking..Might be third row down..lol. I don't recall off hand if speaker and power is two different plugs.

As far as the RCA.. 4 volt.. some here swear to the clarity of the system done this way..

 

I am not going to argue here but most of the 4v preamps are not full band at that measurement. Most fudge the number by lowering some of the resistance values to show a higher number. Since the connected device is typically higher than these lower specs the unit will never output the figures being marketed.

The concept of high voltage preamps was created to help bring down noise levels by providing high gain at the head end and allowing the consumer to reduce the gain applied by the amplifier. Sadly most shops and consumers see this as a way to make systems louder by overdriving the gain stages in the amplifiers. The other advantage to the high volt preout was in the early days when a system shared a single preamp pair to run multiple amplifiers there was not enough output to properly drive a bunch of amps off a single 1v -2v preamp section. Since most amplifiers today require less than .5v to drive them to full output it seems that there is no need for more than that on a single line. However at the same time where head unit preamps got more powerful, amplifier companies began to make amplifiers more sensitive to win the "This ons louder on the display board" at retail store fronts. The result was noiser amplifiers, collapsed sound stage, overheating issues from being overdriven 100% of the time and overall less sonic performance. Since we now have two or more outputs on head units each providing more than 1v there is no reason for more unless you plan to split those lines to drive multiple amplifiers. Today we see more and more high level circuits being used for the very same reason high voltage preamps made their way into car audio. High signal output means less gain added by the amp. Since that step down function is controlled by the amp, there is a perfect match, and as such reduced noise and opportunity for no ground loop issues make it a favored OEM connection.

If you throw any voltage at the factory amp you will get sound, but you will fail to drive the amp to full power or drive the head unit into clipping before you get close to getting the amp to its rated output cleanly thus producing bad sound, destroying speakers, or worse killing the input stage of the factory amp.

 

Not going to argue either.. mines wired to speaker leads and I'm happy.. others HAVE done 4v pre amps and are happy.. no room for an argument there.

OP.. keep in mind you will have no "front - rear" speaker control without doing surgery to wiring at the amp.. Just an "in case" thing there.

 

Since the amp built into my radio died I had to wire it to preouts, pretty much because I am too cheap to buy another HU. Mine puts out 3.5V to the preout lines, works just fine.

Sorry to the OP for not coming back to clarify my original statement. The wire I had to move was in the adapter harness, which I bought from Best Buy.