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Front fog lights as cornering lights

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COMMUNITY-SOURCED · MK5 · LIGHTING

The fog light on the side you're turning toward comes on at low speed with the headlights on.

Applies to
VW Golf Mk5 (1K: Golf, Rabbit, GTI, R32), 2006-2009 US / 2004-2009 elsewhere, with front fog lights and a 30-byte BCM coding.

Not confirmed for
17/21/23-byte BCMs, Jetta Mk5 (option names match, but the byte positions aren't confirmed), 2010 Jetta, Golf Plus, Audi A3 8P

Module
09 Central Electronics. vag-coding.net: only for cars with a '30-byte' BCM coding. Ross-Tech's platform page confirms 30-byte Highline/Midline BCM variants exist alongside 17/21/23-byte ones.

Method
Long coding + Adaptation

Requires
Front fog lights fitted. A 30-byte BCM coding, per vag-coding.net only.

1 · Before you start

Run a full Auto-Scan and save it. Copy the whole long coding string of each module you change, and write down or screenshot each adaptation value before you change it.

2 · VCDS

  1. Write down the current 09 long coding.

  2. Open 09 Cent. Elect. > Coding - 07 > Long Coding Helper (sub-system '0').

  3. Tick 'Internal Turn Light Control Algorithm active' (vag-coding.net: Byte 23 Bit 2).

  4. Set the turn-light source to 'Turn Lights via Fog Lights'. vag-coding.net shows this as a drop-down in Byte 23 Bits 3-4 (value '08'), not a checkbox. Note the current selection before changing it.

  5. Save. If new Adaptation - 10 channels appear for dimming in/out time, adjust them if you like.

  6. Test with the headlights on, turning the wheel or using the signal in the turning direction.

What this changes

Byte 23 Bits 3-4 is a single drop-down selection (vag-coding.net). Choosing 'Turn Lights via Fog Lights' replaces whatever turn/cornering-light source is selected now. No source lists the other options or says what a factory car normally has there. Fog lights keep working as fog lights.

Notes

Ross-Tech marks this 'when applicable'.

Sources: wiki.ross-tech.com · wiki.ross-tech.com · vag-coding.net · vag-coding.net

Reference only. No guarantee of compatibility. MK6IX doesn’t answer coding questions or troubleshoot coding. Back up your original coding before making any change. You code your car at your own risk.

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