How to install a new head unit?

August 14, 2008 5:51 PM

car audio filter: Trying to replace the head unit on my car and I'm getting lost in the wiring harness and install instructions. (lots of questions inside)

This may be a really specific question but I'm trying to wire a JVC KD-AHD39 into my 2004 Mitsubishi Lancer Ralliart. The Lancer has a subwoofer and an amp under the driver's seat.

The harness in the car has 5 wires attached and the harness that was sent from crutchfield only has 4. First question is : Any ideas on what the extra wire is?

The manual for the JVC head lists one of the leads as the "Accessory Terminal". Second question: Is this the line that runs to the switched power? (The extra diagrams seem to suggest that but I'm not electrically inclined and I'd rather not blow anything up)

The crutchfield wiring harness has a line coming out of it called "Power Antenna". It matches a wire in the harness in the car but I have no idea what it is and I can't find a wiring diagram for the car. Any idea what a "power antenna" is

There is a remote lead coming out of the JVC that is supposed to be for other equipment. The install instructions list that as the line to run to the remote power on for extra amplifiers. There is a line in the crutchfield harness that is supposed to be an amplifier turn on, but the crutchfield wire has a special end on it. The wire from crutchfield is a bare wire. Are these two wires meant to be together or do I have the connection completely messed up?

Second to last question (sorry for the mega-post): I'm not completely sure how the subwoofer gets tied into the new system. There doesn't seem to be anything in the crutchfield harness that mentions a subwoofer.

There is a chance I ended up with the wrong harness from crutchfield and I'm trying to call them (they are backed up at the moment). Are there any other things I can do to learn some of these answers for myself?

posted by ibfrog to technology (6 comments total)

A power antenna is exactly what it sounds like--it goes up when you turn on the radio, and it goes down when you turn it off. If you had a power antenna, you'd probably know it.
posted by box at 6:03 PM on August 14, 2008

ok, crutchfield finally let me in.

The Power Antenna is actually a powered roof antenna. Its not motorized, but it boosts its signal. It and the Amplifier turn on wire both go to the remote line which means I need to do some cutting before I splice the lines together.

Accessory Terminal is the switched power (at least I got one right).

The extra wire is for the dimmer line that lets you control the illumination with the dimmer dial in your car. Its not a widely support feature of most after market car stereos.

Looks like the subwoofer is figured out by the amplifier so I don't need to do any extra wiring to tie that in.
posted by ibfrog at 6:09 PM on August 14, 2008

Oh, man, that's embarrassing. So there's more than one kind of power antenna. You learn something new, and so forth.
posted by box at 6:19 PM on August 14, 2008

That "power antenna" lead could be used for either type of powered antenna, actually.
posted by kindall at 7:12 PM on August 14, 2008

So apparently the best answer here is crutchfield support. The system is in and running perfectly now.
posted by ibfrog at 9:00 PM on August 14, 2008

Its not a widely support feature of most after market car stereos.

On the contrary. Most aftermarket stereos will come with:
Left front +
Left front -
Right front +
Right front -
Left rear +
Left rear -
Right rear +
Right rear -

In addition, they might come with RCA cords to make all the above irrelevant if you have an amp.

In addition to the additional, they will come with:
Power line (12v)
Ground
Switched power
Power antenna
Dimmer
posted by Civil_Disobedient at 4:06 AM on August 15, 2008