H11 to H9 Headlight Conversion

Since this thread's been resurrected, I'll report that I've had this mod for over a year in both my vehicles with absolutely no problems.

I'm very happy with the results.

 

Today I learned what he word gendarme means.

Also, like what @xliderider stated above, I have had no problems in my vast experience with this mod (ok, it's only been a week, but better light than stock)

 

I just wanted to add a couple of notes. First, using H9 bulbs may not be compliant with the applicable standard in the Prius' headlight housing (Department of Transportation FMVSS No. 108, Table XVIII). As far as I know, it's illegal to use anything other than the specified bulbs in headlights' housings, which would mean using H9 bulbs is illegal. However in my opinion, this is similar to driving 5mph over the limit; as the bulbs just have a higher output but the same light pattern, the headlights will still have the sharp cutoff needed and not cause excessive glare to other drivers. Your chances of being ticketed for this are virtually non-existent. This is much much better than the many people I see out there with HID or LED kits in stock housings causing terrible glare for other drivers.

Also, if you want to get the best output from your lights, you can re-aim them. There are many tutorials out there on how to do it, which aren't hard if you can follow a technical tutorial. I can't speak for the 3rd gen, but on the 2nd gen it was easy for me to do. In Colorado, the law is that the bright part of the headlight's beam can't extend more than 100ft. from the car on flat ground with the low beam on (note - please see exact law's language, this is from my memory, I take no accountability!). In some states, this is 75ft. Therefore I was able to aim my headlights a touch higher using a parking lot with 10ft wide parking spaces.

 

When I perform conversion, I also had a number of hot spots. Out of desperation, I changed the HID bulbs out until I found 2 lamps that did not have any hotspots. That was last year.

 

I just wanted to add that I did the H11 to H9 conversion on my Gen 3 - modifying the new bulb housing was incredibly easy. I used a pair of side snips to cut the extra tab out in the plastic housing, also used snips to modify the one metal tab that was keyed wider at the opposite side. Got old bulbs out easily and the new ones in without any hassle (other than it being 20 friggen degrees out.. brr!)

A few pics, description in order of pic.
Before - comparison of socket.
Before - comparison of metal tab - Black tip is H11 bulb
Cutting the metal tab smaller - used some Harbor Freight blue small side snips
After

Also read horror stories of getting the passenger bulb out - it was a heck of alot easier than I anticipated. I had a heavy hoodie on which protected my wrists from the sharp metal edges and tight gloves so I could feel the tab. Didn't need to remove anything. (And I don't have small mitts, just long fingers...)

I don't anticipate THAT much better light, but the stock lighting is terrible. For the cost, why not? All in all, it took me like 2 minutes to modify both bulbs.

 

Yeah, it's definitely worth a try! I thought it was even easier than expected. And as an added bonus - everywhere around here H9's are a couple of bucks cheaper than H11's.

 

I just did the H11 to H9 conversion, and am quite pleased with the results. For the cost of some labor, 10 watts per bulb, and a shorter bulb life, the H9s produce a noticeably brighter light without blinding other drivers.

The conversion is a bit tricky without the right tools. Fortunately, I was able to get a bunch of good quality tools a few years ago, though I don't know what many of them do. From this cache of tools were a few wirecutters and snips. Luckily, I found only one side snip that was able to do a relatively clean job of snipping through the plastic tab inside the socket. Unfortunately, it didn't do a 100% clean job and didn't make it completely flush, so I anticipate my next light change will be tricky getting the H9 bulbs out.

That was the easy part.

The more difficult part was the metal tab by the bulb assembly. I only had one tool that could even cut through the metal, and it did a lousy job at it. I managed to gnaw away at it enough so that I could pull the pieces with a needle nose plier. I then uses a file to trim down the burrs and get the remaining metal down as much as possible. But I was still left with a 1mm remaining piece of jagged metal sticking from the bulb base.

Fortunately, it still managed to fit inside the assembly. I was hoping that the headlight housing tolerance would be large enough, and luckily it was.

All in, the job took me close to an hour, though to be fair, I've never changed out a headlight bulb ever.

My tips to make the job easier:
1. Get a good pair of strong snips with enough leverage but small enough jaws to cut through the metal tab.
2. Use side snips to cut the plastic socket tab. Just keep snipping untkl
3. Or, just get a Dremel tool to do both.
4. Follow the car's instruction manual to remove the existing bulb.
5. Use the existing bulb to practice putting in and taking out the bulb a few times to get a good feel for how the bulb should twist into the headlight assembly.
6. Make sure the electrical connector will connect to and release from the altered H9 bulb. Do this a few times until it feels relatively loose enough that you can release the bulb fairly easily
7. Put into the new H9 bulb into the headlight first. Once it's in, snap on the electrical connector.

If you have thick arms and hands, you may need to disconnect a few hoses and parts to get to the passenger side headlight bulb more easily. Fortunately, my arms and hands are skinny enough that I was able to get to the bulb no problem.