There are obviously quite a few differences in the coding. Picked below those that seem to be related.
May be far fetched but byte 18 is the light setup - which is now different in the modified van, and also in the coding- would be my best/only guess. Possibly then another try on byte 19.
Byte#
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
62 F8 79 3A 0A 21 20 93 01 28 4F 60 2D EB 87 F4 C0 B4 73 89 E0 45 79 C0 32 04 00 3F 08 60 MY16 Panel Van OEM LEDs tailgate
A0 A8 39 3A 0A 61 34 13 93 28 4F 40 2D EB 87 F4 C0 94 73 89 60 45 79 C0 33 04 00 3F 08 60 MY18 Panel Van OEM LEDs tailgate
A0 A4 30 3A 0A 61 34 B1 93 28 4F 74 6C EB 8E 74 8F A0 70 8F 60 CC 6D 60 32 04 00 22 08 00 65Plate PV
Byte 18 is light setup, the OEM configuration has bits 0-1 set unlike the now modified van.
Bit
7654 3210
---- ----
0111 0011 OEM MY16 Panel Van
0111 0011 OEM MY18 Panel Van
0111 0000 65Plate PV
Byte 18 Bit 0~7 00 Light Setup: Standard/Parameter Settings (EEPROM)
Byte 18 Bit 0-1 01 Model parking light: 5W + 5W (Ausführung Standlicht: 5W+5W)
Byte 18 Bit 3-4 00 Indicator lights: 21W/21W/5W (Ausführung Blinkleuchten: 21W/21W/5W)
Byte 18 Bit 5 Output high beam active (Ausgang Fernlicht aktiv)
Byte 18 Bit 6-7 40 Brake lights: 21W/21W/5W (Ausführung Bremsleuchten: 21W/21W/5W)
Byte 19 is lamp diagnostics stuff. The proposed bit 6 to turn off tail light monitoring was already the same as OEM. Also setting the byte the same as OEM "89" seemed to rule out the difference in control method (bits 1,2). May be worth another try after modifying byte 18?
Bit
7654 3210
---- ----
1000 1001 OEM MY16
1000 1001 OEM MY18
1000 1111 65Plate PV
Byte 19 Bit 0 Control of fog/cornering light via pulse width modulation (PWM) active (Ansteuerung Nebel-/Abbiegelicht über Pulsweitenmodulation (PWM) aktiv)
Byte 19 Bit 1 Control of rear lights via pulse width modulation (PWM) active (Ansteuerung Begrenzung-/Schlusslicht über Pulsweitenmodulation (PWM) aktiv)
Byte 19 Bit 2 Control of brake lights via pulse width modulation (PWM) active (Ansteuerung Bremsleuchten über Pulsweitenmodulation (PWM) aktiv)
Byte 19 Bit 3 Control of indicator/turn lights via pulse width modulation (PWM) active (Ansteuerung Blinkleuchten über Pulsweitenmodulation (PWM) aktiv)
Byte 19 Bit 4 Lamp Diagnostics for Turn Lights active
Byte 19 Bit 5 Lamp Diagnostics for Fog Lights and/or Cornering/Turn Lights active
Byte 19 Bit 6 Lamp Diagnostics for Tail Lights active
Byte 19 Bit 7 Lamp Diagnostics for Brake Lights active
Byte 27 - mostly undocumented.
Bit
7654 3210
---- ----
0011 1111
0011 1111
0010 0010
Byte 27 Bit 0 License plate light in LED design (Kennzeichenbeleuchtung in LED Ausführung)
Byte 27 Bit 1 Activation terminal 58d active via Body Control Module (BCM) with pulse width modulation (PWM) (Ansteuerung Klemme 58d über Body Control Module (BCM) mit Pulsweitenmodulation (PWM) aktiv)
- - - - - - - - - - - - - - - -- - - - - - - -
Byte 11 has some more lamp diagnostics stuff but nothing obvious.
Bit
7654 3210
---- ----
0110 0000 OEM MY16
0100 0000 OEM MY18
0111 0100 65Plate PV
Byte 11 Bit 0 High beam via shutter (xenon) active/installed (Fernlicht über Shutter (Xenon) aktiv/verbaut)
Byte 11 Bit 1 Lamp failure detection for additional position lights active (Lampenausfallerkennung für zusätzliche Positionsleuchten aktiv)
Byte 11 Bit 2 Activation of additional position lights via pulse width modulation (PWM) active (Ansteuerung zusätzliche Positionsleuchten über Pulsweitenmodulation (PWM) aktiv)
Byte 11 Bit 3 Additional position lights installed (Zusätzliche Positionsleuchten verbaut)
Byte 11 Bit 4 Activation of Back-Up Light via pulse width modulation (PWM) active (Ansteuerung Rückfahrleuchte über Pulsweitenmodulation (PWM) aktiv)
Byte 11 Bit 5 Activation of license plate light via pulse width modulation (PWM) active (Ansteuerung Kennzeichenbeleuchtung über Pulsweitenmodulation (PWM) aktiv)
Byte 11 Bit 6 Lamp Diagnostics for Back-Up Light active
Byte 11 Bit 7 Lamp Diagnostics for License Plate Light active
Byte 16 - more lamp diagnostics.
Bit
7654 3210
---- ----
1100 0000 OEM MY16
1100 0000 OEM MY18
1000 1111 65Plate PV
Byte 16 Bit 0 Activation low beam via pulse width modulation (PWM) active (Ansteuerung Abblendlicht über Pulsweitenmodulation (PWM) aktiv)
Byte 16 Bit 1 Activation of fog light via pulse width modulation (PWM) active (Ansteuerung Nebelschlusslicht über Pulsweitenmodulation (PWM) aktiv)
Byte 16 Bit 2 Activation of Daytime running lights via pulse width modulation (PWM) active (Ansteuerung Tagfahrlicht über Pulsweitenmodulation (PWM) aktiv)
Byte 16 Bit 3 Activation of High Beam via pulse width modulation (PWM) active (Ansteuerung Fernlicht über Pulsweitenmodulation (PWM) aktiv)
Byte 16 Bit 4 Lamp Diagnostics for Low Beam active
Byte 16 Bit 5 Lamp Diagnostics for Rear Fog Light(s) active
Byte 16 Bit 6 Lamp Diagnostics for (Separate) Daytime Running Lights (DRL) active
Byte 16 Bit 7 Lamp Diagnostics for High Beam active