Orion 225 HCCA Mystery Wire

I bought a orion 225hcca from e-bay that I believe is 1st gen.  I have a wire that is soldered to the board that exits the grommet where the power and ground wires come out.  I have not hooked anything up yet as I am wondering what this wire is.  The remote turn on lead as I understand is the blue wire at the plug on the other end of the amp.  I do not know what this wire is for as the amp power and ground leads have been lengthened with some thicker streetwire, maybe someone added  this for some reason? or is it factory?  If you have an idea about these amps, reply and I can e-mail a pic as I cannot send a pic that big to this server.  The other thing is about bridging.  I know I have to use the 400 bdg bridging module (which I have) but I have found conflicting information on which wires to use.  Thanks in advance.always need more power

The wire in question grounds the shield of the RCA jacks.  If your amp has engine noise, you can try grounding it.  It may help the noise.

Yellow and orange. Leave the black wires alone, in bridge mode. I don't remember EXACTLY which is positive and which is negative, (and generally, it won't matter) but those are the wires to use when bridged.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Well that clears up those questions, now that the amp is ready, the sub queations have arisen.  I have a 10" Kenwood DVC sub that I bought new and it has played a total of 10 minutes- 5minutes before burning one amp and 5 minutes before burning another.  I thought maybe after the first one that maybe the amp was just crap (ebay buy) bought another one after having repaired it and burned it down too.  Before this went any further, I took the sub to the place I bought it today and asked them to check it out- he checked the wiring (I had it wired positive to positive, neg to neg, so he said that was alright- he checked the resistance of the coils with the wires hooked together and it read 1.5 ohms, with the wires diconnected one coil read 3 ohms and the other read 2.9 ohms.  He said the sub is garbage.  Is he right?  The coils were supposed to be 4 ohms each.   If so what sub do you recommend (10") for the 225 hcca.  I want SQ not SPL.  Loud is great too though lol!always need more power

The impedance of the coils are 4 ohms.  The resistance of the coils are obviously 2.9 and 3.0 ohms.   Impedance is an AC measurement.  Resistance is a DC measurement.   The woofer is fine.