Removing the Prius door-edge lights

a.k.a. our 12 volt battery doesn't need quite this much courtesy

[Most images are linked to larger versions.]

A problem that frequently surfaces in the forums is when someone leaves a door ajar in a Prius and comes back some time later to find the 12 volt battery totally discharged and unable to boot up the car. The usual cause is from various interior lights staying on because a door is not fully closed. While it is possible to switch off the front and rear dome lights and the one in the hatch so they don't go on when doors open, there are two more "courtesy lights" in the lower edge of the front doors that are easy to miss noticing and ironically enough, can't easily be disabled by switches. (Really, all the interior lights should be on some kind of timer circuit...) Since the 12V battery used in the Prius is a smaller capacity because it doesn't do the engine-cranking, it can become discharged sooner than other cars' units.

However, it's easy to remove the offending light bulbs and disable the courtesy lights too. This shows how easy it is, even for those not very mechanically inclined. All you need is a small screwdriver or similar tool. After doing this, you can leave the doors open as long as you like and the long-term drain on the battery is no more than with the doors closed. While you should be careful to fully close the doors when leaving the car unattended, this will prevent the common case where a door that mistakenly got closed only to the "first click" and is still ajar won't flatten the battery after sitting for just a day or two. Most 12V batteries never quite recover from a complete discharge, and have diminished chemical capacity from then on.

Pry gently under the right-hand end of the clear light cover. Always go for the right-hand end regardless of which door you're working on -- so it's at the rear edge on the passenger door, and toward the front on the driver's.

Tilt the light unit out of the hole and gently remove it, trailing the wire behind it.

Push the little release tab on the connector and back it out of the clear housing to disconnect it. Ahhhh, darkness at last.

Now we can get a good look at this thing -- a somewhat odd construction of clear plastic and metal strapping. The inner cover over the lamp has ventilation slots in it to let heat out without melting the plastic. If the light has been on for a while, LET IT COOL before proceeding further.

Squeeze the inner cover gently at the ends and tease it out of the shell. The large bump [arrow] will probably release first; then persuade the other end out from between the lamp leads and separate the halves.

Grasp the bulb and gently wiggle it out of the spring clips to remove it. The small tool can also be used between the clips to carefully push it out from behind.

Amazing that such a small and innocuous thing can sometimes cause such a big headache to the car owner. But why??
Because each lamp draws on the order of 300 milliamps, or about three and a half watts. That doesn't sound like a lot, but it's over half an amp with both courtesy lights installed and a door ajar, and even more if any of the other interior lights are enabled. Remember how hot it gets after a couple of minutes? That's your battery charge being wasted as heat.

Put the unit back together (sans lightbulb) and reinstall it, to restore appearance and keep all the parts of the shell where they are findable again four years from now when you go to sell the car. The lamps can be used for spares elsewhere around the car -- some other interior lights, for example.

Removal of the courtesy lights may trigger immediate safety concerns about the visibility of an open car door at night. Quite valid, of course, and here's my answer for that:

Five bucks at the local auto parts place buys a substantial amount of reflective tape, including the red and white bands commonly used on trailers. A little creative cutting can produce all kinds of fun shapes. In my estimation, adorning the edges of the car doors provides *more* visibility for approaching traffic than the courtesy lights would, and upon thinking about it I'm rather surprised that there's nothing reflective placed there by the factory. On all cars. Practically free, and no dependence on the electrical system.

[ The reflective-tape game has since undergone a serious upgrade, which see. ]

But it might eventually be nice to have the best of both worlds. Drop-in LED based replacements for the lamps may be available or planned, which would greatly reduce the current drain for the courtesy lights. Ideally, such units could even have self-contained timers so they turn themselves off after a few minutes.

_H* 071116