Wiring an aftermarket head unit to an L w

Here is how I have connected my new Pioneer DEH-P980BT head unit to my 2004 LW300-2 with Advanced Audio. A1-A12 and B1-B12 are the wires on the GM wiring harness. I may have gotten a few of the colors on the car side wrong as some of them are rather subtle. I was not able to find a stock wiring harness that matched this configuration, so I just bought a Scosche GM10B and re-wired it to match. I used a very small "jewelers" screwdriver as a pin extractor. After removing the plastic pin retainers from the back of the connector, I aligned the screwdriver vertically and then from the pin side punched it through the small opening above each pin and then pulled the pin out from the rear, rearranged the pins, then re-installed the pin retainers. I have the head unit sending high level (speaker level) audio directly to the factory amp over the speaker wires without using a high-low converter. The factory amp is apparently designed to accept high level inputs. The factory amp also takes care of the subwoofer output. The A3 amp turn on draws just a few milliamps, so no worries. Everything seems to work just fine without connecting B6 amp ground. However, when connected to A12 it sinks 30-40 milliamps and the variation depends on the volume level. Is that a ground loop or what? I didn't do anything with B4, dimmer, because my head unit doesn't have any way to utilize it. It can and does utilize B12, illumination, though not particularly well. Wires by function A1 - N/C A2 - N/C A3 - Factory amp turn on lead A4 - N/C A5 - N/C A6 - N/C A7 - N/C A8 - Left Rear Speaker + A9 - Left Rear Speaker - A10 - Right Front Speaker - A11 - Right Front Speaker + A12 - Ground B1 - 12V+ constant B2 - 12V+ switched (ACC) B3 - N/C B4 - Dimmer B5 - N/C B6 - Factory amp ground B7 - N/C B8 - Left Front Speaker + B9 - Left Front Speaker - B10 - Right Rear Speaker - B11 - Right Rear Speaker + B12 - Illumination Wires by color from the car side A1 - N/C A2 - N/C A3 - Orange A4 - N/C A5 - N/C A6 - N/C A7 - N/C A8 - Brown A9 - Yellow A10 - Blue A11 - Green A12 - Black B1 - Orange B2 - Yellow B3 - N/C B4 - Gray B5 - N/C B6 - Orange B7 - N/C B8 - Tan B9 - Gray B10 - Light Blue B11 - Blue B12 - Brown Wires by color from the head unit side A1 - N/C A2 - N/C A3 - Blue/White A4 - N/C A5 - N/C A6 - N/C A7 - N/C A8 - Green A9 - GREEN/ Black A10 - Gray/Black A11 - Gray A12 - Black B1 - Yellow B2 - Red B3 - N/C B4 - N/C B5 - N/C B6 - N/C B7 - N/C B8 - White B9 - WHITE/ Black B10 - Violet/Black B11 - Violet B12 - ORANGE / White

Oops, the car is a 2004 Saturn LW300-2 with Advanced Audio.  I hope the info saves the next guy some time as none of the online resources I was able to find had correct info.