Dome light “door” setting = dead battery cell in 1 year

[Randall44]

Summary: You may want to switch your dome lights to “off” (instead of “door”) if it’s gonna sit for days, or your 3rd Gen is not your daily driver.

A great clue: the previous owner sold it to me with no light bulb in the dome light, and a brand-new battery.

The story: My 3rd Gen killed a brand-new battery after a year (dead cell). There’s a leak/drain somewhere in the system when the main (middle) dome light is set to “door”. In another posting, the guy said it was his rear dome light. My rear light tested OK so far, but I’ll test it some more when I get more time. For now, I'm keeping them both in the “off” position if I won't be driving for a few days.

Verified with this method:
Let the battery equalize overnight after charging/driving.
Repeat:
Using a Digital volt-ohm meter (DVOM) on the battery
Got battery reading to 0.01v accuracy. Example: 12.47v. Record the ambient temperature, too.
Dome light set to “off” (doors closed)
Wait 6 hours. Take reading. (and air temperature)
Dome light set to “door” (doors closed, bulb is not lit)
Wait 6 hours. Take reading. (and air temperature)
Repeat

After several cycles of this process (several data points) you can see a pattern.
I eliminated the effect temperature fluctuations may have on battery voltage: I leaned toward taking readings when the temperature had been roughly the same for an hour or two, for both “off” and “door”.

“ off ” position: voltage drops about 0.01v in 6-12 hours
“door” position: voltage drops about 0.11v in 6-12 hours (range was 0.08 to 0.14)

2001 4Runner SR5

 

[cleanrunner]

sounds like a bad door jamb switch or one that is stuck.

 

[Joelzy]

the other day i came in to work early and was a bit tired so i didn't notice that my seatbelt was caught in the door. It latched but was open enough to leave the dome light on all day and completely drain the battery. attempted a push start down a hill but no dice, had to call a coworker for a jump.

after that im a little iffy about having my dome light on "door".

 

[TheDurk]

I would be more interested in direct measurement of key-off current draw at the battery with the switch in off and in door, rather than these voltage and temperature readings. Any decent DVM can do amperage.

My truck can go six weeks and start in 20°F weather and my domes are always in door position. I frequently make long trips to Brazil in the winter. My key-off MA draw is a little under 40mA. So I confess I am skeptical about all this.

 

[OrRunner]

I would be more interested in direct measurement of key-off current draw at the battery with the switch in off and in door, rather than these voltage and temperature readings. Any decent DVM can do amperage.

My truck can go six weeks and start in 20°F weather and my domes are always in door position. I frequently make long trips to Brazil in the winter. My key-off MA draw is a little under 40mA. So I confess I am skeptical about all this.

This is correct.

 

[Jungoes]

used to have this problem if any doors were left partially closed, switched all interior lights to LED's and they don't drain the battery as the normal filament ones do ( which can get Very hot)

if you are checking any other potential drains you cant find, pull the MPX fuse and then check, I pulled that one when I had to park the vehicle for a few months without a battery tender.. cranked solid after 2 months! zero drain anywhere. The inner side of the cover actually has instructions for this fuse.

 

[pluton]

To prevent the dreaded and embarrassing "I left the dome light on all night and now the $270 battery is dead' syndrome, replace the feeble, dim, juice-hungry stock dome bulbs with LEDs.

 

[PRG3K]

I was having a similar problem. My dome light would stay 100% ON even with it set to DOOR and all of the doors closed. I pulled dome light after dome light out of junkyard 3rd gens and all had the same problem. Someone mentioned a faulty door jamb switch and I found this thread on how to replace it: https://www.toyota-4runner.org/3rd-...esy-door-jamb-switch-fix-door-ajar-light.html

 

[AntleredRuin]

To prevent the dreaded and embarrassing "I left the dome light on all night and now the $270 battery is dead' syndrome, replace the feeble, dim, juice-hungry stock dome bulbs with LEDs.

This.

 

[TheDurk]

To prevent the dreaded and embarrassing "I left the dome light on all night and now the $270 battery is dead' syndrome, replace the feeble, dim, juice-hungry stock dome bulbs with LEDs.

Yep. Saved my batootie more than once.