LED DRL strip flickering and not active in other light modes (Byte 18 issue)

Nightshades · Post by **Nightshades** » Fri Oct 24, 2025 7:01 am

Hi everyone,

I’m hoping someone here can help me sort out my front lighting setup on my 2014 Scirocco. The LED DRL strips are working again after a lot of trial and error, but not correctly — they flicker and don’t behave as they should in different light modes.

Car details

Model: 2014 VW Scirocco

Region: Netherlands (LHD, originally German)

BCM: PQ35 Highline (shows in VCDS as “BQM PQ35 H”)

Headlights: Factory xenon

Background
My dad works at a VAG dealership here in The Netherlands. We used the VCDS they use there to try to enable my rear taillights to stay on with DRL. While doing this, we mistakenly changed Byte 18 in 09 – Central Electronics → Coding-07 (Long Coding Helper).
That completely broke my LED DRLs — they were dead in all modes, and I had a city light fault on the dash.

I tried to get in contact with Ross-Tech, but they refused further support because I wasn't the registered buyer for the VCDS interface we used, since it belongs to my dad’s dealership, and the original registered buyer no longer works there, so the license can’t be verified.

What’s been done so far
Tried several Byte 18 values from online references — they didn’t help.
Another coder (with VCDS, VCP, and ODIS) managed to get the LED DRL strips working again on the DRL setting only.

However:

The LED strips now flicker or blink intermittently.

They turn off completely when switching to city lights, dim lights, or full beam.

They should remain on (as position lights) in those modes.

A BCM reset in ODIS was attempted by my dad, and by the coder multiple times, but failed. It reports a generic error and refuses to reload the factory parameters.

Fuses, wiring, and LEDs themselves are fine.

Current situation

LED strips work but flicker and only in DRL mode.

They switch off in all other light positions.

City light fault still present on the cluster.

All other lights (low beam, high beam, fog, turns, tails) operate normally.

If anyone has

A PQ35 Highline (“BQM PQ35 H”) BCM from a Scirocco with factory LED headlights,

Or can share their Byte 18 value and/or full 09-Central Electronics long coding,

Or knows how to force a correct BCM reparameterization (via ODIS Engineering, VCP, or VAG CAN Pro) to remap the Leuchte channels properly,

Or knows how to fix this issue in another way,

…I’d really appreciate the help.

What I can provide

Full VCDS Auto-Scan

Current 09 long coding

Channel map for 09 (Central Electronics)

Fault codes currently stored

Happy to post or send them if it helps identify the correct setup.

Thanks a lot in advance for any advice or reference coding you can share, any working reference from another 2014 Scirocco would be incredibly helpful.