Hate your halogen bulbs? I did too! HID H7 DIY Installation E90/E92 - Bimmerfest - BMW Forums

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Old 12-22-2010, 10:29 PM
E90 Vanessa CP's Avatar
E90 Vanessa CP E90 Vanessa CP is offline
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Mein Auto: E90 N52B25
Lightbulb Hate your halogen bulbs? I did too! HID H7 DIY Installation E90/E92

This was super easy and I'm a chick q; so I have confidence in you all. If your Bimmer's LCM isn't flashed for xenon/ bi-xenon (mine wasn't) this is what you need to do unless you go back to the stealership.

Let me know if you have any questions or if something isn't clear. I typically don't write up DIY Tutorials so don't be a meanie and make me

This is a repost of my original thread. I'm reposting this with the info in the body of the thread instead of just the attachment :thumbsup:

#1) Connects to Driver side headlight ballast.
#2) Connects to Passenger side ballast
#3) Grounded to the positive battery terminal in engine bay
#4) Grounded to the chassis (negative ground)
#5) Connects to the capacitors for the Driver side headlight
#6) Mounts anywhere away from area that will be hot

This Document is writing based on the following

Model Origin: USA
Make: BMW
Year: 2006
Model: 325i
Sub-model: Sedan
Chassis Code: E90
Engine Code: N52B25

Changing the bulbs

Remove the plastic panel in the wheel well by turning the 2 dials on the panels. Once you loosed the dials, push up and pull out.

You will see the dust cover for your low beams. There's a metal bracket holding it in place. Pull that metal bracket up and pull the dust cover down and out through the wheel well.

(In the picture below the wheel well panel was already removed. I used this picture so you can see the dust cover and the dust cover brackets in the picture but I took it once I installed the HIDs so yours will not have a hole with wiring coming out. I also circled the bracket that hold the dust cover in place )

Drill a small hole (about 1- 1 ¼" diameter) in the dust cover for the wires to be able to go through.

To remove your Halogen bulb remove the two metal brackets holding those in place by pushing them both in together (they bottom of the bracket is in a hole on each side of the light) and which pushing them together push up to release the tab at the top which helps hold the bracket in place.

(In the picture below I already removed the brackets that hold the bulb in place)

Remove the bulb by pulling it out of the housing and removing the OEM harness from the bulb. The bulb has 2 prongs that looks very similar to any USA household plug. Pull the bulb straight out while holding the OEM harness and being extra careful not to rip or damage it.

(The picture below I circled the OEM harness so you know what it will look like)

***Before we go further, FYI ***8594; never touch the HID bulbs directly unless you are wearing rubber gloves, and even then I wouldn't risk it. The natural oils in your skin short the life of the bulb tremendously***

Attached the 2 spade into the OEM harness, and put the HID bulb into the housing making sure it's aligned and won't fall out. It will feel loose when you put it in the housing . This is normal. Make sure when putting the bulb into the housing that it is aligned correctly. Also make sure to check the front of the headlight as well.

OEM Bulb

Checking the alignment from the front of the headlight

Replace the metal bracket that goes over the bulb. I put electrical tape over the back the of the bulb and bracket because they bulb felt loose. This helps prevent you to not ruin the alignment of the bulb while finishing the wiring that is attached to the bulb. To clarify, the electric tape is not necessary, to me it made it easier, however, you can install this kit perfectly fine without it.

Pull the 3 wires you are left with through the dust cover as well as the rubber seal and replace the dust cover over the back of the housing. Pull down the metal bracket to ensure its secure.

The rubber seal should be pushed up against the back of the dust cover hole to prevent moisture that will fog your headlights.

Replace the wheel well panel making sure the 3 wires are pulled up into the engine bay. If you don't you will have a hard time getting the out without having to go back and remove the wheel well panel.

The 3 wires that are coming out from the HID bulb through the dust cover that should be pulled up into your engine bay now need to be connected. There should be 2 male, 1 female and they will only fit by size to the corresponding part of the harness and ballast.

The 1st male goes into the load capacitor, the 2nd male and the female go into the ballast.

After those 3 wires are connected on both sides, looking at the engine bay, on the right-hand side..
***8594; Connect the other side of the ballast to wiring harness male #1 (see picture at the top of the wiring harness)
***8594; Connect load capacitor male to wiring harness female #5 (see picture at the top of the wiring harness)

Go to the left-hand side of the engine bay…..
***8594; Connect the other side of the ballast to wiring harness male #2 (see picture at the top of the wiring harness)
***8594; The load capacitor on passenger side connects to nothing

Time to ground the harness

Any time you work on electrical grounds in your car, I always recommend disconnecting the battery, which is located in the trunk. If you feel there is not chance you will hit the metal body in the engine (which will spark) then at your own risk, skip this step.

Disconnecting the battery…..
Using a 10mm socket wrench or ratchet driver, remove the nut, washer, and battery hold down plate. Pull up on the metal unit that connects over the negative terminal on the battery and wrap it with a towel so it doesn't fall, make a connection and restart the battery. You will notice the trunk light go out. Don't close the trunk or you will not have a easy time getting back in.

Now we are left with wiring harness grounds #'s 3 and 4

***8594; #3 of the wiring harness (see picture at the very top for the wiring harness wiring diagram) is red which is going to be grounded to the positive battery terminal in the engine bay. Remove water prevention cap over the positive terminal and using a 10mm wrench remove the nut and the wire that is currently connected. If the terminal ground is dirty, use acetone to clean it to ensure a strong connection. I put #3 of the wiring harness on the terminal first and then put the OEM harness that was originally connected over #3 of the wiring harness. The order of which wire is grounded to the terminal 1st and 2nd doesn't matter too much. I wanted to make sure it stayed in place since #3 of the wiring harness was smaller than the OEM wiring harness. Replace the nut back on the terminal, and put the black plastic water prevention cover back on.

(Circled below is the water prevention cover that is over the positive terminal in the engine bay)

Removing the water prevention cap

Red positive wire grounded to the positive terminal in engine bay

Grounded positive terminal, water prevention cap back on

…..now to the chassis grounding

***8594; #4 of the wiring harness (see picture at the very top for the wiring harness wiring diagram) is black and will be grounded to the chassis ground in the engine bay, aka the negative ground. In order to access the chassis ground, we need to unclip the window washer fluid neck. Push in the tab and pull up the window washer fluid neck as shown in the picture. Pull back on the fluid neck so you can easily access the chassis ground. Using a 10mm socket wrench remove the nut over the chassis ground and remove the OEM wire harness that is currently connected. If the chassis ground is dirty, use acetone to clean it to ensure a strong connection. Ground #4 of the wiring harness, put the OEM wire harness back on the chassis ground, and replace the nut.

Washer fluid neck that must be unclipped and pulled back. Circled is the tab you pull on to unclip the neck.

Chassis grounding

Make sure the wires are flat against the grounds and the nuts are securely in place. If these steps were not done correctly it can causing a shortage in power, or cause the HIDs to flicker.

Mounted right hand driver side ballast

Mounted left hand passenger side ballast

I circled the picture above and below of where I grounded #6 (See very top of wiring harness wiring diagram) Please note it's not grounded to power.

Before HIDs

Finished Product

The positive wire doesn't normally stick out that much. I took this picture before I pushed it back more into the bottom on the engine bay


Last edited by E90 Vanessa CP; 12-22-2010 at 11:04 PM. Reason: the post added its own "check ebay for bulb kits"..wtf? i didnt put that!
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