How to Enable Daytime Running Lights via Fog Lights on VW Golf MK5 2006

This guide shows how to enable the Daytime Running Lights via Fog Lights function on a VW Golf MK5 (1K) by changing a single bit in the long coding of the Electronic Central Electric module (09). Once enabled, the front fog lights come on automatically (typically at reduced intensity) whenever the car is running and the main lights are off, acting as DRLs.

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Used tool in this guide

Video: How to enable DRL via fog lights on VW Golf MK5

This video shows how to activate Daytime Running Lights via the front fog lights on a VW Golf MK5 (1K) using the iCarsoft CR Max, by setting bit 4 of byte 18 in the long coding of control module 09 – Electronic Central Electric.

Supported vehicles

Vehicle
golf-mk5

Technical overview

Item	Details
Vehicle	VW Golf MK5 (1K)
Year	2006
System	09 – Electronic Central Electric (BCM / Bordnetz)
Procedure type	Long coding – single bit change
Difficulty	Easy
Time required	~5 minutes
Prerequisites	VAG diagnostic tool with long coding support, 12 V battery in good condition, ignition ON

Step-by-step procedure

1. Plug the diagnostic tool into the OBD2 port. On the Golf MK5, the port is located under the dashboard on the driver’s side, behind a small flap below the steering column.
2. Switch the ignition ON without starting the engine. Make sure the battery is in good condition — coding writes that drop out due to low voltage can leave the module in an inconsistent state.
3. Open the iCarsoft CR Max, select VW and let it identify the vehicle / select Golf MK5.
4. Open the control unit list and select 09 – Electronic Central Electric (sometimes labelled Central Electrics or Bordnetz).
5. Open Coding / Long Coding. The tool will read the current software coding and display it as a long hex string (e.g. 098D0F27 00 41 80 00 14 00 00 14 00 00 00 01 97 07 5C FF).
6. Write down or photograph the original coding string. This is your fallback if anything goes wrong — you can always restore the car to its original state by writing this exact value back.
7. Locate byte 18 in the long coding and tick bit 4 – Daytime Running Lights Via Fog Lights. In the iCarsoft helper this option is shown as “10, Daytime Running Lights Via Fog Lights” — the “10” is just the option index in the iCarsoft list, the actual location in the coding is byte 18, bit 4.
8. Confirm the change. The tool will calculate the new coding string and ask The new code: … Are you sure to set the new code? — press Yes.
9. Wait for the “coding successful” confirmation, then exit the module and switch the ignition off.
10. Switch the ignition back on (or start the engine) with the headlight switch in the OFF (or AUTO) position. The front fog lights should now come on as DRLs. With dipped beam or full beam selected, the fog lights drop out of DRL mode and behave normally again.

Restoring the original setting: open module 09 → Long Coding, replace the current string with the original one you saved in step 6, write it back. Bit 4 of byte 18 will return to 0 and the fog lights will stop running as DRLs.

Additional Information & Compatibility Notes

Before using or purchasing any diagnostic tool for this procedure, always verify compatibility with your exact vehicle model, year and system configuration. Supported functions may vary depending on software version, hardware revision and regional limitations.

Alternative tools

• Best VAG OBD2 tools

Related guides & background information

• How to use VAG long coding

Legal & safety notice

This procedure modifies vehicle system settings through the control module. Incorrect use may cause faults or warning lights. Always ensure the vehicle is secured and follow proper safety procedures.

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