I'm installing a bluetooth amp in place of the factory head unit to play music in my car, but I'm having trouble getting power to it.

My old head unit had two connectors going to it, one that fed out to all the speakers (brown) and one that powered the unit and did some other functions (gray). I got the appropriate Metra harness and plugged both connectors in properly. I then wired the speakers to the amp's speaker output and soldered the ground and the yellow battery wire from the Metra harness to the amp's power and ground wires.

When I turn on the car I get no power to the amp. I checked the 15A fuses in the cabin fuse box and the 15A fuse on the amp itself. All are good. I also tried hooking up the red wire from the Metra to the amp's yellow battery wire, thinking I might have chosen the wrong one. No dice. Note that the amp doesn't having any sort of red wire coming from it, but it does have a blue "power control wire," the function of which isn't made entirely clear in the instructions. Any idea how I should troubleshoot this next? I'm stumped. Do I need to bypass some sort of security function to make it power up? I've seen various videos/guides that show it working without any special steps.

 

I can't help answer your question but this is one reason I stayed with the stock radio and added the Grom Audio Bluetooth adapter. Plug and play. The Grom uses the CD changer jack in the back of the stock head unit. Works perfectly for both phone calls and streaming music and podcasts.

Good luck to you, but if you remain stumped you might consider returning the unit you bought and going with the Grom.

 

Update:

To avoid confusion, this is what I'm dealing with:

From the Metra harness, I have:

* four RCA connectors for the speakers
* Yellow wire labeled 12v Memory
* Red wire labeled 12v Power
* Blue and white wire labeled Amp On/Off
* Black ground
* Two other irrelevant wires (antenna, illumination)

From the amp, I have:

* Eight speaker wires, which I've reduced to four female RCA connectors that I've soldered in
* Yellow "battery wire"
* Blue and white "power control" wire
* Black ground

I've hooked up yellow to yellow and blue-and-white to blue-and-white with no response. Also tried to connect the red wire from the metra to the yellow battery wire of the amp, with no response.

The setup is shown in the attached picture. Circled on the left are the RCAs coming from the amp (out of picture to the left) to the metra (out of picture to the right). The two circled wires at the top are the blue-and-white "amp on/off" wire and the yellow "12v memory" wire. As you can see, I have them jumpered to the amp's yellow battery power wire and the circled blue-and-white "power control" wire. There's also a ground wire, which is hard to see in this picture, but it's connected.

It seems perhaps the amp has to be sent some kind of signal through the "power control" wire for it to turn on. That normally would be sent by the head unit, but I don't have one and don't want one. I'm a bit stuck here.

I did jimmy up an iphone directly to the car speakers through the Metra RCAs and all speakers played music successfully, so clearly the Metra harness connection to the speaker system isn't in doubt.

 

The Grom sounds great, but my main goal in this installation is to get rid of the head unit entirely.

 

I've solved it and it's working great now. I just needed to connect the red ACC wire from the Metra to the blue and white "power control" wire of the amp. The presence of another blue and white wire coming from the Metra was a red herring.

I hope this might be useful to someone else who has similar issues in future.

 

On a related note, does anyone have a good resource for the routing of wiring for the audio system? I'm looking through the "harnesses" section of the repair manual and there's some semi-useful stuff there, but I don't see any good guide online on how everything is routed (physically, not electrically).

After doing some research, it looks like I'm going to have to install a new larger power wire from my amp directly to the battery. I'd like to do so in an elegant way if I'm going to do this.

 

What are you going to replace the head unit with? I've always wanted to use that spot for... Something. Also what Bluetooth setup did you get?

 

For the Bluetooth setup I'm using a KAC-M1824BT, a small marine/car amplifier that's Bluetooth-enabled. The amp is wired up to the speakers and power through the stock connectors to Metra adapter. It works well so far, but I haven't had much time with it. I'm planning to run a new thicker power wire directly to the battery with its own fuse, along with a thicker ground – I likely would be fine with stock wiring, but want to be careful.

As for the head unit, I haven't fully thought it out, but I'll likely put a piece of aluminum or steel over the hole. My "dream" setup would be to have wireless charging and a way to stick my phone there magnetically, but I haven't yet explored the feasibility of this.

 

If can make a suggestion... run a wire from the main power in the engine bay fuse box to a relay and small fuse block under the passenger seat. Autozone or anyplace should have all of that, then activate the relay with any switched power from the main fuse box on the driver side cabin. Because of the location under the passenger seat (where the CD changer is/was) it is easy to run wires under the carpet to the dash or wherever and easy to change out fuses.