It is a harness that comes with the aftermarket Blau's. 4 RCA's & the amp turn-on. Apparently, it won't work correctly with the OEM Ford Blau, though. [mad]
I have a harness with a yellow connector that came connected to the back of the HU, but I haven't been able to track down the other end yet. I took apart the left-side carpeted panel in the cargo area, hoping to find sub amp wiring preinstalled. No dice.
I really like the stock MP3 HU, and want to keep it, but I'm not a big fan of line-level convertors. I even thought about soldering in a couple sets of preouts at the HU amp, but after taking the HU apart (I'll deny having done that later), it would be impractical at best.
I'll either stick with a mono sub amp, wire in the preouts, go with the converters, or go with an aftermarket HU. Haven't decided.
I measured it to chassis ground.
It's not that unusual to trigger a sub amp with an audio signal from the source. The sub amp in my home theater system is the same way. I don't use the auto turn-on function because it isn't sensitive enough to come on when the volume is low. I use an X-10 remote and receiver to turn on the amp manually instead.
I tested the sensitivity of the 4.5v enable signal and it was very good. I started with the volume all the way down and monitored the voltmeter as I slowly raised the volume. The voltage went up with the slightest turn of the knob, even before I could hear anything!
I am still looking for the right relay or other component that will trigger with 4-5 volts. I tried Radio shack and they had only 12 and 24 and 120 volt relays.
Can I leave the second set of RCA's connected in C4 Security Alarm and Pin C5 Ground on the stock yellow harness without ill effect? Won't be using them at all; just sub set. I know blue wire has to be rerouted. Don't want to cut them unless I have to.
There is and Ebay Shop that claims they have prototype Sub and Cd Changers Contols for the Ford/Blau due out sometime in March. I used his conversion harness for the radio and that worked fine.
Did you find that the stock HU subouts were standard Rca voltage? Hooked everything up and tested, but the sub volume seemed low. I am using a Standard Woofer and Box with a small MTX sub amp. You can notice the sub but it seems a bit dull low in volume is low. Any suggestions? I was thinking of replacing the 8" sub with an MTX model, but wanted to make sure everything was functioning properly before I threw money at it. Don't know what the the orignal sounded like so it's kinda hard to have a reference.
So I guess my question is: are standard RCA out or something Ford cooked up voltage wise to match their amp and make upgrading harder?
The sub out is standard low-level but it somewhat lower than normal. I had to turn the gain on my amp up to about 3/4 as high as it goes. It is crossed over very low and may seem less loud because of that. You won't get much mid-bass, only deep bass.
It sounds like it is working fine to me. I am using a 10" sub in a custom panel/enclosure I made in the rear of my Wagon. I would find a 10" driver that will match your box and re-cut the hole to fit. I started with an 8" but did just that when I wanted just a bit more punch.
Yet Another question: I have been having problems with the wiring. I have Rca going to Pin 1 and the other going to pin 2. They use pin 3's shield. When I plug in one I get sound from sub - no sound when I try them together. Am I missing something or am I stupid?
You should only have 1 RCA connected to pins 1 and 2. Pin 1 being the tip or positive lead and 2 being the shield or negative. The third ground on pin 3 is to shield the other two for their long trip back to the sub amp. I used a 2 conductor shielded Mic/Guitar cable for this. The shield ground is only connected at the Pre-out side to avoid ground loops.
The way you have it now,when you connect both of your RCAs at your amp, you are canceling out the signal. The amp sums the 2 inputs for your mono sub signal internally.
I assume you have either a mono sub amp with inputs for right and left stereo signal. OR
a stereo amp bridged to mono for your single sub.
After you wire it correctly you will have only one RCA for you sub signal. Use a Y adapter or just split the end and connect two RCAs in parallel on your cable on the amp side.
I hope that clears it up.