HID Bulb Types and Identification – D1S D1R D2S D2R D3S D3R D4S D4R etc

You may have seen references to various D-Series HID (xenon) bulbs in the context of projector swaps, D1S, D1R, D2S, D2R, D3S, D3R, D4S, D4R, sometimes even D2C and D2H. So what’s the difference?

All of these bulbs have the quartz envelope and arc positioned in the same place – so any D-series projector can use any D-series bulb by bending/cutting out the indexing tabs. For example, if you buy a AL Gen2 projector from an Audi but want to use aftermarket D2S bulbs + ballasts, just bend down the key tab! Please don’t use D*S bulbs in reflector headlights as it will effectively be a high beam!
HID bulb types. Read more about them in this HIDPlanet thread. ECG is the technical name for ballast. All aftermarket ballasts are designed to use D1 and D2 bulbs only, and will not operate the other bulb types.

D-Series Naming System

D-Series bulbs are named using 3 characters, like “D1S”.

D - "Discharge"
N - 1,2,3,4 is the type
T - S is for projector, R is for reflector

To illustrate this

1. Ignitor: integrated (D1*, D3*) vs. separate external (D2*, D4*)

The D1 and D3 bulbs have an integrated ignitor (silver box) on the back of the bulb. D2 and D4 bulbs use ignitors that detach and stay with the headlight.

Igniter built-in: D1, D3
No integrated ignitor: D2, D4

2. Voltage: mercury (D1*, D2*) 85V vs. mercury-free (D3*, D4*) 42V

Mercury bulbs (D1S, D1R, D2S, D2R) run at 85V AC. Mercury Free (hg free D3S, D3R, D4S, D4R) bulbs run at 42V AC.

3. D*S is used in projector vs. D*R is used in reflector headlight with shield on envelope glass

S series bulbs (D1S, D2S, D3S, D4S) are used in projector lamps, R series bulbs (D1R, D2R, D3R, D4R) are used in reflector lamps.

Bulb Identification

What if you are given D1R and D3R or D2S and D4S without label? You can’t see if there is mercury inside (and thus the voltage). It is possible to differentiate using the notches on the bulb.

Location of notches on D-Series bulbs
This diagram shows the notches on the bulb base, looking at the bulb, as well as the location of the notch on the lamp holder (in red)

Aftermarket Bulbs

Again, all of these bulbs have the arc in the same place, so to reduce the number of different models to produce aftermarket manufactures have developed the D*C type, which universally fits multiple notches. For D1/D3, a removable ignitor adapter is available.

5 notches? What is going on?? These are “Type-C” bulbs
4 and 5 notch D-Series bulbs are type “C”

Aftermarket manufactures don’t want to make a lot of different models. D2C that can replace both D2R and D2S. D4C for D2S, D2R, D4S, D4R and D2C. D1S with 5 notches won’t be hard to understand.

D2C replaces D1S and D2S, D4C replaces D3S and D4S

All of this makes it simpler for production, but much more complicated for consumers… And most sellers even don’t know about the real reason or the difference.

C-type bulbs with integrated ignitors can be differentiated by the keying on the ignitor connector

Another way to differentiate D1S vs D3S is based on the keying in the ignitor connector.

Finally, the last aftermarket type is sometimes called “D2H” which includes AMP connectors for aftermarket ballasts. It is always 85V / Mercury.

Aftermarket bulbs (used when the OEM ballast fails, or for projector swaps) with AMP connectors are sometimes called “D2H”, and have enough notches to fit anything.

Many thanks to this post, and the HID planet thread.

AL Gen2 Projector “de-key” Modification

You can easily modify AL Gen 2 projectors to fit any of the D base bulbs by bending the key tab out of the way (aka dekey the projector):

This is the key tab that prevents using a D2S bulb in a D4S or D8S projector
Key tab partially bent on an AL gen2 projector
Finishing the bend, using pliers to curl it completely out of the way
When complete, the back should look like this.

How to: “factory” wire bi-xenon solenoid

I had previously written up how to create a bi-xenon high-beam adapter using a 9005 extension. If you don’t mind modifying your headlights permanently, and have long enough wires on the solenoid pigtail (8~10″), with a little work you can mimmic the “factory” solenoid wiring found in the OEM AL bi-xenon headlights that use “Gen 2” (2-wire) (aka “E46”) projectors. This will also work for replica projectors, but not 3-wire “Gen 1” projectors – those require a solenoid controller.

You will need: 9005/9006 female crimp terminals, a molex crimp tool, a wire stripper/crimper, a paper clip, and some zip-ties.


First start by removing the terminals from the OEM 9005 high beam connector, by inserting a paperclip to depress the retaining tab as shown below.

Removing a terminal from the connector housing.

Next cut off the OEM terminal, re-strip the wires, and include the pigtail wire:

In addition to the two original brown wires, I’ve added a third black wire that runs to the solenoid ground, shown here inserted correctly into the terminal prior to crimping.

Using a molex-type crimper, ensure that the terminal is securely fastened to the three wires.

Crimping in progress, showing the correct length of stripped conductor and insulation position.
The new ground terminal after being crimped. The same process is repeated on the supply (yellow, +12) side.

The same process is repeated on the other wire (yellow, +12v). Finally, insert the new terminals into the housing

Insert the new terminals into the OEM housing. Retaining tab faces center.

Finally, zip tie the new wires along the harness, and plug it in…

Ziptie everything in place, and it looks totally stock!

This not only looks nicer, but also frees up some much-needed space inside of the housing.

How To: DRL Disarm aka LSM Position 0 Disable

This How-To describes what I will call the “DRL Disarm” (because “DRL Disable” has been used extensively to mean the VIDA software part #30679690) – making it safe to retrofit HIDs in P1 Volvos using the SKBOWE error harness. The “Dimmed Low Beam” DRL issue with HID conversions in P1 only occurs with the LSM in Position 0, as shown below, so this mod prevents the CEM from sending low-duty-cycle PWM to the HID ballasts during the day, when the LSM is in Position 0 (“off”), essentially turning Pos 0 into Pos II.

OE USA SWDisable SWDRL Disarm
Pos 0 (Day)Dimmed 9VOffPWM 13V
Pos 0 (Night)PWM 13VOffPWM 13V
Pos I (1)Off (parking)Off (parking)Off (parking)
Pos II (2)PWM 13VPWM 13VPWM 13V

Many advantages to this solution:

  1. It’s super easy!
  2. It’s free! No cost to flash software, or need to explain to dealer, or record with Volvo.
  3. It’s 100% reversible (also free) if you need to remove the HIDs later
  4. Just as safe as DRL disable for SKBOWE operation
  5. Function compared to stock remains unchanged (low beam still on in Pos0), in regions where DRLs are required, this keeps the functionality intact.

Only disadvantage compared to DRL disable is that you can’t be cool and turn off your lights (not that you could before!)

Remember, you don’t *have* to do this – the same thing is accomplished by leaving the LSM in PosII all of the time. But it prevents any potential issues if you (or other driver, or shop) forgets to do so.

How does it work?

Inside of the LSM, there are two small switches, one for Position 0, and one for Position 1. There is no switch for Position 2 (which is detected when neither 0 or 1 is closed). The CEM thinks that the LSM is in Pos0 when Pin 6 of the LSM (black/green wire, and B:2 of the CEM) is connected to ground, so by disconnecting this wire as shown in the diagram below, the CEM will never think the LSM is in Position 0, and the daytime dimmed DRL condition can not occur!


The LSM in position 0
For reference, this is the LSM in position “0”, when DRLs are activated on cars with the CEM program installed.
LSM diagram with pin 6 hack
By removing LSM pin 6 (shown by red X above) the CEM will never think the LSM is in Position 0.

You could cut this wire and be done in 10 seconds, but this can be done reversibly in about 5 minutes. Either way, it’s simple, effective, and free!

How To: Reversible DRL Disarm

Step 1: Gather Tools / Materials. Easy!

Gather parts: Small flat screwdriver, spudger, large paperclip, and electrical tape
  • Large paperclip, or other similar size stiff wire. You could probably use a small/normal size paper clip, but the large ones are exactly the right size to release the pins.
  • (Optional) Small flat screwdriver to disengage connector lock
  • (Optional) Nylon spudger to remove LSM
  • (Optional) Electrical Tape will to secure the removed pin.


Step 2: Remove the LSM. This is easiest using a non-marring spudger, but if you don’t have one: Grab the door-facing panel inside the jamb by the air grate and pull out, then push the LSM out from the backside. Once it’s free, disconnect the electrical connector.

Removing the LSM
Remove LSM using spudger. Alternately, pull out the cover to the side of it and push it out from the back.
LSM removed
Once free, remove the LSM and disconnect the electrical connector.

Step 3: Identify Pin 6. It’s the black/green wire as shown below.

Back of LSM with Pin6 circled
Back of the LSM, showing location of Pin 6
LSM connector showing Pin6
Back of LSM connector showing Pin 6. It’s the black/green wire in MY2005

Step 4: Unlock Pin Retainer Clip. Careful as to not break it off, slowly pry up the pin retainer clip. It swings up and out. I find a small flat-head screwdriver works well for this.

Unlocking the retaining clip
To unlock the retainer clip, insert screwdriver as shown and carefully pry up.
Retainer clip disengaged
Retainer clip disengaged. The little plastic tabs are a backup mechanism hold the pins in place.

Step 5: Remove Pin 6 from the connector. This is super easy once you get the hang of it, but if it’s your first time, it can be a little tricky. Unfold the paperclip and insert it into the upper hole above pin 6. It will slide in easy at first, then there will be some resistance – keep pushing until it gets firm. Then, keep slight inward pressure with one hand, while pulling the wire out with the other. If lined up right, the wire+pin should come right out.

Bent paperclip
Bend the paperclip straight to make a pin remover. Large paperclips work best for the Green Volvo Connectors
Shows where to insert paperclip
Insert paperclip into the remover slot for Pin 6 (click for bigger).

If you can not easily pull the wire out, remove and re-insert the paperclip, maybe wiggle a little bit. The pin should come out with very little force at all. If you pull too hard, it will break the primary retainer plastic and you won’t be able to re-install the pin later.

Step 6: Remove and Secure Pin 6. Once the pin is out (left) replace the retainer clip by pressing it back down gently into the connector. Use some tape (right) to hold the loose pin out of the way.

Pin6 removed.
Pin 6 halfway out of the connector. After pulling it all the way out, press the retainer clip back down gently into the connector.
Pin 6 taped back
Tape the loose wire to the harness so it looks like nothing ever happened!

Step 7: Installation is reverse of removal… It’s now safe to run HIDs with SKBOWE in any LSM position! The low-beams will turn on in Position 0 and Position II.

LSM installed
Reinstall LSM, ensure that the lights come on in 0 and II.



AL Projector (“E46”) Identification Chart PDF

I put together a nice cheatsheet to help identify the right type of AL projector when you are looking at listings or out at a salvage yard.

Download the full PDF: AL Projector Identification Guide

The AL Projector Guide (V1).


You want to look for “Gen 2” projectors, they have the best optics and the wiring is simple. Gen 1 requires a solenoid controller for bi-xenon functionality.

Remember that aftermarket ballasts only run D2S bulbs. To use D1/D3/D4 bulbs you need an OEM ballast. D2S bulbs will fit in any of these projectors. The ones with octagon-shaped bulb holders might need a simple modification to allow them to take D2S bulbs. All of them with black plastic rings are designed specifically for D2S.

Low Beam Patterns

High Beam Patterns


Links to Full Images (click to show)

How To: 9005 to 2-wire Bi-Xenon Solenoids

Here’s a quick writeup on how to make a “9005 to 2-wire solenoid” adapter, for connecting bi-xenon projector (e.g. AL aka “E46”) actuators to the high beam circuit inside the headlight housing of your P1 Volvo without permanent modifications (i.e. cutting wires). This assumes that you have the pigtail for the projector – if not, you’ll need to get that, too.

Wiring the "E46" AL projector bi-xenon solenoid using using a 9005 extension
Wiring the “E46” AL projector bi-xenon solenoid using using a 9005 extension
If you have 3 wires coming from your projector pigtail, and/or 3 wires running from the green circuit board to the coil, the connections are more complicated and you will need to get a 3-pin controller or use the BMW OE ballast.
Step 1: Cut off the loom to get at the wires

The 2-wire solenoid is connected in parallel with the high-beam bulb, so we need a connection to both wires, and the easiest way to do this is using a 9005 (aka HB3) extension. I used the iJDMToy adapter which has a ceramic output connector (probably intended for “hyper” watt cut-coil bulbs) and seems to be acceptable quality. The black loom was not split, so I had to cut it off.

Step 2: Cut extension, strip the wires to prepare for crimping.  Never use “t-taps” or “quick-taps”

Cut the extension, preferably as far away from the output (bulb side) as possible while leaving enough wire to work with on the input side. Strip off 1/4″ (6-7mm) of  insulation from the projector and the extension wires. If possible, try to find some high-quality butt-connectors (e.g. 3M) that have glue-lined heat-shrink (or use uninsulated ones and add your own shrink). The glue acts a stress relief which is important in automotive applications to stop vibration stress at the crimp point.

Step 3: Crimp on the output (female) ends. Try not to get too close to the middle until the other side is in.

I like to light crimp the easy side (close to the end of the barrel) before doing the tricker 2-wire connections. Once you’ve got the output side lightly crimped, twist the positive (pin 2, red or yellow wire) and the negative (pin 1, black, brown, or green wire) to the respective wire on the input side (male) connector and finish the crimp.

Step 4: Crimp the input side with the projector solenoid wires

Once everything is nice and tight (check by pulling hard on the wires) use a torch or heat gun to shrink and seal them.

Step 5: After shrinking, it’s done!

You can reuse the loom for a nicer look, not really necessary though..

With original loom reinstalled.

And that’s it!


Interestingly, I haven’t found many places you can buy these pre-made…

  1. AliExpress has them in bulk lots


The solenoid connector (female) is TE AMP 9-1718346-1 (replaces 968705-1), though 2-1718346-1 will work if you trim a small tab, and takes MQS pins, e.g. 20-18AWG tin is 965906-1, 23-20AWG tin is 962885-1

SKBOWE Install Guide – Retrofit (Initial Draft)

Before I do the final connector termination I wanted to get together an install guide, and might as well practice what I preach, so my car it is. It took me 15 minutes to install the SKBOWE pair while taking pictures and figuring it out for the first time.

Ironically it took about 30 minutes to get the original pre-KBOWE out. I forgot how big of a PITA it was to get that thing installed.

kbowe vs skbowe
The original KBOWE (with Nick-inspired heatsink upgrade c. 2015) on the left, a SKBOWEv2 on the right. Next level.
The last flight (probably) of the original pre-KBOWE, holding 50W under 1V pk-pk ripple at 50% PWM. Goodbye, old friend!

Just for the record, it still works fine – 8 years later (2009-2017) – still under 1V pk-pk at driving 50W at 50%PWM. Anyway, out with the old, in with the new!

Step 1: Pull the pin

pull the pin to release the headlight
Step 1: Pull the pin.

JKJK if you can’t figure out how to get your headlights out of a P1 car please return your SKBOWE .

Real Step 1: Mount SKBOWE

The recommended quick-install mounting location is behind the OEM GDL (gas discharge lamp) control module cutout, directly behind the headlight housing. The best way would be to drill two holes in the upper member and secure the SKBOWE with stainless screws like my ballasts are:

Recommended SKBOWE mounting location (left)
Recommended mounting location – left side looking at car from front, behind the OEM GDL cutout.
Recommended SKBOWE mounting location (right)
Recommended mounting location – right side looking at car from front, behind the OEM GDL cutout, beneath the fuse box.

But I know 99% of you won’t do that (and it’s hot outside), so for demonstration purposes here’s how one might secure them with zip-ties (included) in about 30 seconds.

SKBOWE installed with zip-ties (left)
The quick/easy/sloppy install: zip-ties (left side looking at car from front)
Quick/easy/sloppy install (right)
Quick/easy/sloppy install w/zip-ties (right side looking at car from front)

Fits like a glove! Alternately, depending on how your ballast is mounted you could shove them in the gap between the quarter panel and wheel well, and secure it with a single zip tie or industrial strength velcro (not included)

Step 2: Ground SKBOWE

The recommended grounding location is the M8x1.25 quarter-panel mounting bolt at the top of the headlight housing opening. This was painted with the car so you will need to clean it up.

This is the most important step in the install process – the grounding is what protects your WMM

You should really use a Dremel Tool with a burr or sanding disk, but I will include a small piece of sand paper in the kit for those who don’t have them. Using the sand paper will take a long time (spend 5 minutes per side)! THE METAL HAS TO BE SHINY.

Cleaning the bolt
Cleaning the paint off of the top threads and insert nut on this bolt. This is the most important step in installation.

Once the bolt is clean, route the ground strap up and around to come in from behind.

This bolt is clean. I used a diamond burr in a Dremel Tool for this side.

I will include two M8-1.25 stainless nuts with each kit. Tighten the hell out of this nut.

tighten the nut
Tighten down the M8-1.25 nut. If you have a DMM, check the resistance between the braid and the engine block or negative on the battery. If the bolt was cleaned right, it should be < 1 ohm.

Step 3: Install the Ballast

Make sure to mount the ballast such that the connector(s) won’t collect water:

Diagram showing which way to mount ballast (this side up)
Make sure the ballast connector(s) are facing downwards (best) or sideways (ok) so that they won’t collect water.

9005/9006 connectors from Headlight -> SKBOWE -> Ballast. It only hooks up one way.

Connect the ballast and headlight

Do check to make sure the red goes to red (or +), black to black (or -), 99% of manufactures use the same configuration (as does the SKBOWE) but it never hurts to check.

Here’s a diagram if you are having trouble with my blurry iPhone pics

SKBOWE connection diagram
SKBOWE connection diagram


If you want to get fancy and have the Morimoto ballasts, the “Nick-style” setup which eliminates the need for a grommet is shown below. This is exactly how the original BMW E46 Gen1 headlight assemblies were wired, with both the ignitor input and 12V output passing through the housing.

Install using morimoto ballasts 3 and 4-pin SuperSeal connectors to eliminate the need for a grommet, and allow the ignitor to easily be replaced.
Super clean “nick-style” install for Morimoto ballasts using 3 and 4-pin SuperSeal connectors and a custom harness to eliminate the need for a grommet, and allow the ignitor to easily be replaced. DO NOT USE THIS METHOD FOR BALLASTS WITH INTEGRATED IGNITORS!

Note that this only works for ballasts with detachable ignitors, since there is only 85VAC or so in the blue/green wires. Don’t even think about running the HV (20kV) next to battery voltage!


Start out testing by activating the headlights with the engine off just to make sure everything is hooked up right.

Activate follow me home lighting
To turn on the low beams with the engine off, depress the high-beam lever to the “lock” position. The low beams will turn on for about 2 minutes (follow me home).

If that works, button her up, do a quick FOD check, fire her up and go for a spin! Enjoy your beautiful error-free headlights.

no bow
No “Bulb Failure” message here – must be a SBKOWE

Ballast Recommendations

Attention: This is an old post (June 2017)! Please see the retrofitting guide for up-to-date ballast recommendations.


I have been reluctant to endorse specific manufactures, but so many people are asking that I will list a few here.

Note that I don’t get kickbacks from any of these sites. A lot of the parts can be obtained cheaper elsewhere (especially if you are not in the US). I have personally ordered from all of the vendors listed on this page, so I feel comfortable recommending them, but do shop around (e.g.  eBay)  if price is a discouraging you from attempting a retrofit.

There are two options for HID retrofits – reuse the stock projector with re-based capsules, or replace it with a full Bi-Xenon1 setup (e.g. E46) that uses D2S bulbs.

Learn more about projector retrofits from this great tutorial at TRS.

After choosing rebase vs projector swap, you’ll also need to choose a wattage – either 35W or 50W. All automotive HID capsules are designed to run at 35w and are rated to last 2000 hours or so at that wattage. Driving a 35w capsule at 55w produces much more light output (+40%), but reduces the lifespan by 50% to 1000 hours or less.

Stock Projector +Retrofit Ballasts

This is the easiest and cheapest option, basically, you install the HID capsule into your existing headlight projector, it fits in like a normal H11 (or H7 in Europe) bulb. Since the projector’s reflector/shield/lens was designed for halogen bulbs, you won’t get a super crisp cutoff or bi-xenon functionality, but it’s essentially plug-and-play aside from drilling one hole in the headlight access door for the pass-through grommet.

Along with your SKBOWE, you need to order a standard HID kit, either 35W or 55W, for the type of low-beam bulb your car is fitted with.

50 Watt Options

Please see the retrofitting guide for up-to-date ballast recommendations.

  • HID50’s ULTRA kit – My personal favorite. I have been using these in my car for nearly 8 years. Have replaced the bulbs 4 times, and the ballasts once (after 5 years, the rated lifespan). Rock-solid dependable and very bright.
  • Morimoto XB55 (AMP) – Everyone seems to love these. high quality, waterproof, reliable products.
  • DDM 55W Slim – Not the highest quality, but a great price and a lifetime warranty. The SKBOWE will run these just fine… You’re spending nearly $100 on the error eliminator so that you can use any brand of ballast, if you don’t mind replacing them every 2 years (for free), the DDMs are a great choice.

The benefits of using the stock projectors are that it is inexpensive, simple, and MUCH brighter than the stock halogen setup.

Downsides are lousy cut-off, sub-optimal beam distribution, and no bi-xenon high beam. The cutoff and distribution can be improved by fitting clear lenses to the factory projectors as the stock lenses are textured to reduce filament shadowing – TRS sells the requisite 3″ ZKW-R lenses here.

cutoff from an H11 retrofit, factory lens

Bi-Xenon Projectors & Ballasts

The Bi-Xenon conversion is a lot more involved, and there are no “easy answers.” Many ways to skin this cat:

  • E46 projectors (salvaged from BWM) are a direct swap – you can remove the P1 factory halogen projector and screw in an E46 bi-xenon projector. Examples this one by forcefed on swedespeed or this one on HID planet. Sourcing genuine E46 projectors is getting more and more difficult, and there have been several (low quality) replica batches produced that work their way to eBay other online retailers. Your best bet is to find actual projectors from a salvage yard – but good luck with that! They are in super high demand. For a retrofit bi-xenon setup, I would recommend going with the Morimoto XB35 (D2S) or Morimoto XB55 (D2S) ballasts for the best performance and lowest EMI, though the back cover might need modification. For an easier fit, go with the AMP version of the ballasts and get a D2S -> AMP adapter.
  • You source salvaged (or new, at $800/ea!) FACTORY bi-xenons, and re-wire them to run off of the halogen circuits but you will still need the SKBOWE. The road-following and self-leveling will not work (this has been discussed ad nauseam), and it’s generally agreed that the quality isn’t great. However, the ballasts are included and are actually integrated into the headlight housing, which makes for a cleaner look. This would require a custom SKBOWE setup, please contact me if you are interested in more information.
  • There have been many custom solutions that get the best projectors using adapter brackets. You’re on your own there!

Advantages going with the bi-xenon retrofit route are that it’s by far the best looking light output, distributed correctly, with more light during high beam and a crisp cutoff.

Downsides are that it’s much more expensive, may require invasive headlight surgery, requires additional wiring for the solenoid, you’re on your own for aiming, and the replacement bulbs are more expensive.

cutoff from an e46 retrofit

After doing a projector swap, be sure to aim your headlight level correctly: danielsternlighting.com/tech/aim/aim.html