2005 HID Headlight Plug issue (plug looks burned or corroded)

Ubertam · Oct 7, 2012

I thought I had a bulb problem that started about 1.5 years ago. My passenger bulb went out. The dealer convinced me to replace both bulbs and charged $400 for it. No big deal. Bulbs go out.

4 months later, the passenger bulb went out again. I got it replaced under warranty and figured it was a fluke.

3 months later, the passenger bulb went out yet again. I got it replaced under warranty again.

3 months after that, it the passenger bulb went out AGAIN. It was nearing the end of the warranty and I realized the problem wasn't with the bulb anyway, so I didn't take it back in yet (it sucks to have to arrange for a ride and leave your car all day to go to work).

I decided I was going to do the work myself so I didn't have to pay another $400. I watched some youtube videos and bought Philips bulbs from Amazon ($50/ea) and went to replace both bulbs. I did it and it worked and I was thrilled. Only $100 and it was kinda fun to work on, anyway.

20 minutes later, the passenger bulb was out again. Crap.

If it's not the bulb, maybe it's the ballast. It's always the passenger side bulb, so that would make sense. I bought a new ballast from eBay and took out the entire headlight, plopped it on my dining room table, and replaced the ballast (way easier than I ever thought it would be) using a YouTube video for instruction.

That seemed to fix it. For a week. It went out again. Did I get a bad ballast? I asked the guy on eBay and he recommended that I try testing by moving the headlight to the other side and plugging it in. I did that yesterday and found that it worked on the driver's side. I moved it back to the passenger's side and it also worked. WTH?

That's when I examined the plugs. Ohhhhh. The plug is messed up. That explains why any time it would get unplugged and plugged back in, it would work for a short time. Simply unplugging it and plugging it back in fixes it temporarily. It's not a new bulb issue. Not a new ballast issue. It's the freaking plug.

Take a look at the picture below and tell me if you think it can be fixed. I just saw another thread where someone had a burned plug (hopefully worse than mine) and the dealer said it would be $4000 to replace the whole wiring harness. I am really really really hoping I can avoid that. Is there any way to replace the plug head or find a scrapyard wire that I can splice safely?

TL;DR: Can I fix this HID headlight connector seen in the picture?

It looks like the left metal contact is lower than the right. If it's physically further away than it needs to be, it could arc when turned on, which could explain the darkening and loss of contact. Does that make sense?

Thanks for the help.

nh7o · Oct 7, 2012

A couple of similar headlight issues today. See the other post in this forum. Replacing the whole harness just because one headlight plug is bad? Unreasonable. See if you can get someone to sell you a plug and pigtail from a wreck, and splice it in with butt crimp connectors.

Not worth while trying to fiddle with the existing connector as it may be deformed from heat, IMHO. It might be possible to clean it up, but it's probably less work to splice in another one.

Britprius · Oct 7, 2012

Make sure the prongs that go into the connectors on the ballast are not corroded before fitting the "new" connector,clean if required. Check the ballasts on both sides and add a little silicon grease to both before refitting to stop further corrosion.

Avi's Advanced Automotive · Oct 7, 2012

I would do one of the following:
1. Get a used connector, release the good terminal from the old housing and corresponding one from the replacement connector, slide the good terminal into the new housing and splice the other wire to your harness with some sort of waterproof connection.
2. Purchase the housing new along with a new terminal, and do the same as above except for replacing the terminal as opposed to splicing.

It is hard to tell if both of the terminals are damaged or not. If they are, replace both.

Used should be easier to work with, however, if you can't get a hold of a used one, do not let the Toyota dealer parts department tell you the parts you need are not available separately.

Ubertam · Oct 8, 2012

Here's a reply from someone on Reddit, where I posted the same situation. I think I'm going to try to clean the connector. It was probably the dealer's fault.

So, What this looks like to me is perhaps the contacts are too loose and you're getting a lot of arcing/carbon build up in the terminals (used to work for Lexus, and I've seen burned up light harnesses-but it's pretty rare), which unplugging/plugging temporarily fixes.
Here's where I think your issue started:
You didn't say what year your prius is (I own a 2nd gem and my bulbs both lasted 100,000 miles roughly) but I'm going to assume your bulb lasted a normal life (because if your car was still under warranty, it'd be at the dealership and you wouldn't be writing us) and burned out under usual conditions.
When the bulb was changed, the plug contacts were damaged. It only happened on the passenger side (which to me is the harder of the two-I did my own bulbs). I'm assuming the tech struggled to get the connector off/on on that side (perhaps a little corrosion had developed prior to the change) and the prongs inside the connector no longer grip the blades that stick out the back of the headlight.
Easy way to tell (and here's where my whole theory goes to hell in a hurry) is if it's fairly easy to get the connector off/on, or it's got play while it's on.
When you have a loose connection, it arcs (again, your burned up plugs suggest a poor connection due to fit, which arcs, which then builds up carbon, which increases resistance, which causes heat and more resistance, which you then just barely scrape off when you change a bulb).
You may be able to take a can of electrical cleaner, and either a points file (can be found at parts stores cheaply) or some other slender file/scraper and clean the contacts inside the plug. At that point, you should then adjust them so they are tight together, so that the plug is a tight fit over the prongs on the light.
If that fails to solve your problem, then I believe you have 3 other options.

cut the plugs off, and disassemble them and replace the internal contacts. I've done this in the shop (Toyota/Lexus doesn't always sell the plugs, and on HID I believe there's no pigtail, the harness just terminates to the plug, and a lot of things are included in the headlight harness like the whole engine/airbag leads etc) and it's not too bad. Only do the passenger side if the driver side is OK.

you can see if 9006 halogen bulb plugs are the same (go to local parts store with your bulb and see if it plugs in). Double check that connectors and wiring appear of the same thickness/gauge. If connector matches, buy it and splice it.

call wrecking yards and see if they will sell the headlight harness (verify that the connectors/plugs are on it). Explain that you only need the "pig tail" for the actual bulb connection and would be willing to take just that part if they offer it. It's possible that nobody will want to chop the sockets off an otherwise good harness, for reasons you can see (can't get them from the factory).

Again, I believe your problem started with the dealership, and had you not stopped going back, you'd have a good case to raise hell and get them to fix this for you, since it's likely they goofed the plug up, but now you've also been in there.
Replacemet parts have a 12 month warranty, and each dealers warranty on labor/workmanship varies a bit.
I'd try calling the dealership, and explain that you've gotten tired of the bulbs always failing, had a 2nd look at the car, since the dealer hadn't solved the issue, and discovered the bad connector-which you suspect they caused with the first bulb change.
Ask them if they will take a look, and that you don't believe you should have to buy a harness to fix what you believe is either a vehicle defect or was caused by workmanship.
Click to expand...

Avi's Advanced Automotive · Oct 8, 2012

Ubertam said: ↑

Here's a reply from someone on Reddit, where I posted the same situation. I think I'm going to try to clean the connector. It was probably the dealer's fault.
Click to expand...

As you can see, the connector has changed color and housing has melted. Cleaning might help for a while, but I would imagine the problem will return.

2005 HID Headlight Plug issue (plug looks burned or corroded)

Ubertam New Member

nh7o Off grid since 1980

Britprius Senior Member

Avi's Advanced Automotive Independent hybrid repair shop

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2005 HID Headlight Plug issue (plug looks burned or corroded)

Ubertam New Member

nh7o Off grid since 1980

Britprius Senior Member

Avi's Advanced Automotive Independent hybrid repair shop

Ubertam New Member

Avi's Advanced Automotive Independent hybrid repair shop