HO GP30 OEM printed circuit boards stuck in "Rule 17" dimming- -UPDATED

[JimJim]

Hello All,
I have three (3) Bachmann HO GP30s: two (2) with factory-installed (OEM- -Original Equipment Manufacturer) DCC-ready Printed Circuit Boards (PCB) with NMRA 8-pin sockets, one (1) with the OEM DCC PCB decoder.
These three (3) units are MUed; originally with Universal consisting.
I am using the Bachmann Dynamis system with the ProBox and 5 Amp booster. I have a stand-alone programming track through my desktop computer running JMRI DecoderPro interfaced with a Digitrax PR3.
Originally I installed Bachmann 2-function (36-552) decoders in the two (2) DCC-ready units with NMRA 8-pin sockets to match the Bachmann OEM PCB decoder.
Because of the limitations of the Bachmann decoders I wasn't able to use  "Rule 17" dimming and Advanced Consisting.
I replaced the two (2) Bachmann decoders with Digitrax DH126P decoders in the units with 8-pin NMRA sockets.
Then I replaced the Bachmann OEM PCB DCC decoder with a "DCC Ready" PCB that I ordered from Bachmann, and added a Digitrax DH126P decoder to the last unit.
After programming all three decoders to their respective addresses- -3001, 3002, 3005, I also changed CVs 49 & 50 to activate "Rule 17" dimming.
Now all three (3) are "stuck" in "Rule 17" dimming.
Using JMRI DecoderPro I confirmed that all the CVs are set to "Normal" function of the lights; FoF & FoR; CV 49 & 50 > Value 0 (zero).
At first, I thought it was a fault with the Digitrax decoders.
I replaced all three (3) decoders with new-out-of-the-package ones- -still no change!
After attempting to reset all three- -CV 8 > Value 008 through the Dynamis DCC system and DecoderPro- -, still nothing.
Unfortunately, Digitrax tech support was of no help. They suggested "resetting" the decoders; CV 8 > Value 008.
I finally replaced the Digitrax decoder with a 2-function Bachmann decoder; which does not support "Rule 17" dimming.
To my surprise, all three (3) locomotives still had "Rule 17" dimming with the OEM Bachmann decoder reset to CV 8 > Value 008.
The problem seems to be with the Bachmann DCC PCB with NMRA 8-pin plugs, both factory-installed and the one I installed to replace the OEM DCC PCB decoder.
Any suggestions as to how to "reset" or "erase" the circuitry in both the OEM PCBs and the replacement board to regain "normal" lighting functions?
Thank you in advance for your time and effort.
J.J.

[JimJim]

Hello All,
Update...
After the above post, I decided to "sleep on it"!
This morning, to confirm that it is the PCB circuitry and not the decoder, I unplugged the decoder and put in the DC 8-pin plug.
I got out my DC controller and attached it to my stand-alone test track after unhooking the DCC DecoderPro.
When I powered the unit up in DC THE EXACT SAME THING HAPPENED! - -"Rule 17" dimming- -in DC!!!
This is a real head-scratcher!
If "Rule 17" dimming is decoder dependent why is it happening in DC???
Thoughts?