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2004 Acura TL electrical mystery

I have a 2004 Acura TL which has been in pretty good shape up until recently.

The left headlight started working on and off spontaneously. I also have noticed that the rear power door locks have been very “sluggish.” Meaning they sound like they are just not powerful enough to unlock the door and often take about 5 or more cycles of lock/unlock to finally work.

I took it to the Acura dealer to take a look at the headlight, and they ran the diagnostic kit and said it looked like I had a faulty headlight electrical setup. However, since this car has the HID headlights, this is no $0.50 bulb repair. They said the bulb, igniter, and ballast, and even the car battery were bad and needed to be replaced which came to a grand total of almost $1000. Ugh.

My question is did the faulty battery cause this? And could my USB cigarette lighter adapter for my phone charger cause a drain on my battery to wear it down? The charger doesn’t seem to use any electricity unless the phone is plugged in and the car running (a light comes on). Or anything else you can think of?


PS: the lesson I’ve learned for my next car is to get one with normal headlights and normal size rims. (the 17" tires are annoyingly expensive!)

If the battery is the original that came with the car it’s old enough to be worn out. Have you had the work done, and is everything now OK, or are you asking for advice before going ahead?

I’d replace the battery and see if the other things work the way they should. A worn out battery could cause all of the problems you listed.

To add to that, I would not replace it with a battery from Acura. They’re fine, but they’re middle of the road quality at premium prices. Be sure you have your stereo and (if applicable) nav codes before you replace the battery so you aren’t locked out of those systems.

You’re right, though - the cigarette lighter is only powered when the key is in the ON position.

Also, don’t do your lights at Acura. They’re an easy DIY replacement, and you can get the bulbs and ballasts for more than 50% off the dealer price if you buy them yourself. Remember that if you replace the bulb on one side, you have to do the other side to avoid a color temperature mismatch.

I agree about the tires, though, especially since most of the tires give an absolutely craptastic ride on this car. I finally found a set that I like - the Michelin Pilot Sport A/S Plus, but you’re right - at just over $1,000 installed, the sticker shock is pretty extreme. Good thing they’re guaranteed to last 40,000 miles.

I doubt that all the parts mentioned for the light are bad. Hopefully you can swap the suspected bad parts into the other good side, one at a time, and verify their condition that way. The shop wants to most likely change all the parts out as a precaution. A possible saved return repair for them but higher costs to you.

As for the door lock trouble I suggest you clean the ground connections from the battery to the chassis. Also make sure that the fuse to the circuit is getting full voltage to it while the locks are being used. If you work on clean the grounds it may help to run a temporary ground bypass jumper lead from the battery to chassis so current to things like the radio memory doesn’t get interupted.

I suspect all of his problems are caused by the bad battery.

Caution, there is 25,000 volts at the HID socket and both the light switch and the battery needs to be disconnected before fooling with this.

In the factory manual there is no mention of checking the battery for proper voltage but I suppose that might make sense. The checking sequence is to check the fuses, checking the bulb for discoloration and the shape of the emitter. Checking the socket for any evidence of discoloration, then trying a different bulb. If its not the bulb, then you are talking the igniter. Usually when the bulb starts to go, the color will first change to a rose color instead of white. But you have to have everything back together again before you reconnect the battery and turn the light switch on. 25,000 volts will kill. I was lucky and the dealer just replaced mine under warrenty.