Steering Wheel Radio Controls Erratic

My 2002 RL has been experiencing erratic behavior when the steering wheel radio controls are pressed. Volume up would change the station, volume down would raise the volume, etc. This was happening on the factory head unit and is even worse with my new Pioneer AVH-5800 deck and the Metra Axxess ASWC-1 steering wheel control interface. At first I thought it might be the AWSC-1, but I did some more tests and I believe the issue is a bad ground in the steering column. I removed the remote radio switch and tested the resistance and it was within factory spec. I took the switch apart and cleaned the contacts just to be safe, but I don't think the switch itself is bad. I then reconnected the switch and tested the resistance between pin 18 of harness c415 which is right below the steering column and the chassis ground. The values were way off from those taken from the switch itself, for example volume up (1800 vs 330 ohms), volume down (925 vs 100 ohms) and audio/ch (1200 vs 770 ohms). I then left the switch connected but removed its ground from the steering wheel grounding point and connected directly to the meter, then I probed pin 18 on the c415 harness again and the values were nearly identical from those taken directly from the switch. So based on this information, is it safe to assume that there is a bad ground somewhere in the steering column? I did try cleaning up metal plates where the grounding point touches the steering wheel. I also tried probing different areas of the wheel to see if there were any better readings but there were not. I had read that there might have been a TSB on the RL for this issue and the solution was to dimple the copper shield over the steering column ball bearing. Has anybody ever encountered this issue and what did you do to fix it?

Thx
Josh