Volvo Halogen to OEM Bi-Xenon Headlight Housing Swap for S40 and V50

This advanced tutorial describes how to re-wire the OEM Bi-Xenon headlight housings to work with Volvo P1 vehicles originally equipped with halogen headlights. The SKBOWE is tapped into the headlight harness outside of the headlight assembly and powers the OEM ballast, so no holes in the housing or cover are required.


Many years ago, I described how to re-wire the factory bi-xenon headlight assemblies as part of an project to facelift a ’05-06 S40 to the new style (’07+) front bumper and headlights with LED city lights. These assemblies are hard to find and very expensive, but offer a unique look (compared with pre-facelift and halogen-facelift) and are technically “DOT Approved” to pass inspection (as they are stamped D2S on the lens).

Note that this mod does NOT give you ABL (active bending lights) or auto-leveling functionality – the motors inside of the OEM bi-xenon housings remain disconnected and unpowered. THERE IS NO PRACTICAL WAY TO GET THIS ENABLED ON A HALOGEN CAR – you would need to change the headlight type in the CEM, add the leveling sensors (which is a lot of re-wiring) and pins in the CEM harness, plus the GDL modules. Sorry, short of creating your own system from scratch, it’s just not practical.

Unfortunately, the original project pre-dated the SKBOWE and the importance of the additional ground was not understood at the time, so eventually (within 3 years) the under-sized capacitor filters I provided failed and took out the WMM. However, with some tweaks to that procedure (described here) to allow using a SKBOWE, the process is just as safe as using an aftermarket ballast.

Install Process

There are two important mods to OEM equipment to make this mod work:

  1. The headlight harness (From the car, with the connector that plugs into the back of the headlight) must be modified to allow inserting the SKBOWE inline on the low beam wire; and
  2. Inside of the OEM bi-xenon housings, connect the pins that are missing in the halogen harness so that the OEM ballast can power up.

Step 1 – Tap Halogen Harness for SKBOWE

To avoid having to drill a hole in the headlight housing and having extra connectors (power in and power out) the cleanest way to get the SKBOWE inline with the low-beam supply is by tapping the OEM harness.

While it is possible to cut the connectors off the SKBOWE and crimp it directly inline, it’s better to just add a pair of 9005 connectors so that you can remove the SKBOWE in the future and go back to stock (just disconnect the SKBOWE and connect the male+female together).

Tapping pin 4 ground and pin 9 low beam with 9005 connectors to allow SKBOWE install outside of headlight housing
Modifications to the headlight harness to connect an SKBOWE without drilling holes in the headlight housing.

You’ll need to find two wires within the split-loom that goes to the headlight connector. you can do the tap anywhere along the split loom, in the image above it’s shown right at the connector for clarity. The pins are:

  • Pin 9 (+) – the low-beam power supply, green/white on my 05 (check your VWD to confirm)
  • Pin 4 (-) – the ground for the headlight housing

The female 9005 (“supply”) goes on the car side, the male 9005 (“output”) goes on the connector side. You can get the connectors for cheap by cutting up a 9005 extension. I like to use heat-shrink butt-connectors for this type of splicing, to keep everything firm and waterproof.

Step 2 – Prepare the OEM Bi-Xenon Headlight Housing

As shown in the wiring diagram below, the HID ballast in the OEM housing is grounded through pin 10 on the headlight connector, which is not populated in the halogen car-side harness. So inside of the housing, you need to connect pin 4 (the halogen and high-beam ground) to the wire that runs to pin 10 (the HID specific ground).

wiring diagram for 2007+ bi-xenon headlight housing s40 v50
Wiring diagram for the facelift S40/V50 bi-xenon headlight housing, 12V section (ABL/AL not shown)

The cleanest/easiest way to do this is by cutting the brown wire going to the four-pin HID connector as close as possible to the main headlight connector’s pin 10 (leaving as much length as possible) and then crimping it into the the the high-beam connector ground, which is visible if you remove the round cover on the top of the headlight.

Alternately, you could use another butt connector, cut the high-beam ground, and crimp everything back together.

Step 3 – Install the SKBOWE

The final step is to install the SKBOWE normally, per the installation guide, including the ground prep and mounting (zip ties or inside of wheel liner on bracket) – but instead of connecting it to an HID ballast, connect it to the 9005 connectors you added in step 1.