Did I botch my headunit upgrade?

[jimothy]

Let me preface this post by saying that I've read the info on TLCFAQ and this forum, but couldn't find specific wiring information. It seems most people here are familiar with basics regarding car audio that I'm not. I have a 2000 LC which had the factory 6disc/tape double din.

I picked up the Metra 70-8113 adapter because I didn't want to mess with the factory amp or speakers. I really just wanted Bluetooth audio so I could play music off of my phone. My understanding was it was direct plug-and-play.

The replacement headunit is a Pioneer single din (http://amzn.com/B01463U20E). Upon receiving the HU, I realized that it did not have the 4 RCA plugs that the wiring harness did, rather it had a +/- for each of the four speakers (FR, FR, RR, RL). So I cut off the RCA tips from the Metra, and used the shielding as a (-), and the interior colored wire as the (+). All of the (-) wires tie back into Pin 16 for signal ground. I left the PWR Antenna cable disconnected, and connected the blue/white AMP wire to the blue/white System Remote Control wire on the Panasonic harness.

Then everything else was Red-Red, Black-Black, Yellow, etc. - and I double checked these with the pin-outs on TLCFAQ. The result is that the new HU turns on fine, but it makes a god-awful feedback noise at FULL VOLUME. Adjusting the volume on the HU makes no difference. Switching inputs also does not do anything. I've tried using the black/white amplifier ground connected to the Black ground, though it wasn't called for in original Panasonic diagram.

When the Blue/White AMP cable is disconnected then the noise will stop.

So I'm thinking I screwed up by cutting off the RCA tips and directly splicing into speaker wires? Did I need to get a line-out converter?

 

[crimsonaudio]

Yah, you're trying to send speaker level (amplified) signal over a preamp line (RCA). If your HU doesn't have RCA outs, you'll need a line level adaptor to pad the level. Just glanced at the HU you bought - it does appear to have stereo RCA outputs on the back (unless those are aux inputs), so you could use those, but you'll lose the ability to fade from front to rear, if that matters to you.

Something like this will work: Scosche SLC4 Line Output Converter

Of course, if your amplifier has speaker level inputs, you can just use those.

 

[LBridges]

I've never heard of someone following the same path you did, but my guess (and that[s all it is) is the problem isn't so much cutting off the plugs, but in using a common ground

 

[jimothy]

Yah, you're trying to send speaker level (amplified) signal over a preamp line (RCA). If your HU doesn't have RCA outs, you'll need a line level adaptor to pad the level. Just glanced at the HU you bought - it does appear to have stereo RCA outputs on the back (unless those are aux inputs), so you could use those, but you'll lose the ability to fade from front to rear, if that matters to you.

Something like this will work: Scosche SLC4 Line Output Converter

Of course, if your amplifier has speaker level inputs, you can just use those.

Ok, that's what I thought. The HU only had 2 RCA inputs, and I believe they are for a Rear Subwoofer, the wiring harness had 4. I thought about using a 2 > 1 RCA adapter, but then I figured it would mess with front & rear sound.

 

[crimsonaudio]

Yah, I'm betting you just need a line level adaptor (if your amplifier doesn't accept speaker level inputs) as right now you're overloading the input stage of your amplifier by feeding it an already amplified signal (speaker outputs are ~12v peak to peak while line level (RCA) levels are 2v peak to peak)...