The wife left the turn signal on after parking a 97 Corolla with the 1.6 engine, and about 11 hours later when she returned to the car, it wouldn't start. She called me for a boost, the battery wouldn't take a boost, the dash lights wouldn't even come on, neither do the headlights. Trying to start makes no sound at all, and the warning lights barely glow at all.

I drove her back home and returned later with some tools. Multi-meter says the battery is sitting at 11.5 V (yikes!), jumping it for an extended period of time didn't change the voltage much, and the dash lights, head light, warning lights still won't come on, still zero sound while trying to start. Looks like the battery is as dead as a door nail.

One odd thing I noticed is that turning the parking lights on creates a faint buzzing sound, as does trying to turn the hazard lights on.

Question: leaving the turn signal to the on position when the car is off doesn't activate the turn signal. How did this drain the battery?


Took the battery and out drove to a parts store where they tested it. The State of Health didn't even register, they replaced the battery under warranty (only had it for 21 months out of a 36 month warranty). Installed the new battery tonight, car fired right up and drove it home. The turn signal ain't the only thing the wife left on. The blower fan too.

Back at home, I did a crude multimeter test and the alternator voltage (14V) is reaching the battery posts (passed the battery terminals).

Update #2

Had the car back in the garage (for a defogger grid line repair), so I took the time to do the parasitic draw test. I get 18-19 mA, both with everything off and with the turn signal to the left or right position. The hazards, when they cycle on, briefly draw upwards of 9A. I tried breaking the connection while they were on, then activated the turn signal and turned the hazards off (trying to keep the relay switched on), but it made no difference. Still at 18-19 mA when I make the connection again (with the multi-meter). Should I just chalk it up to "the battery just went bad all by it's merry self?"

Update #3
Here we are, some 18 months later, and the battery is down to 10V. I obviously get nothing at all trying to start the car. Dash lights do come on though.
I tried giving it a boost, it wouldn't go over 12.05V. Tried starting the car after the boost, I get one crank and then continuous clicking.
I performed a parasitic draw test, I only got 9-10 mA.
The battery is back at the store for a health test, will post back when I get results this afternoon. This is a new battery from Update #1, 18 months old. What kills batteries at 18-20 month intervals? The last time it happened in cold weather, this time it happened in hot weather.

  • 2
    year? make? model? you sure it wasn't the hazards?
    – Ben
    Jan 19, 2017 at 13:03
  • This doesn't sound like the battery is at fault, but rather the connections to the battery. While low, 11.5vdc should be enough to start (albeit sluggishly) most passenger vehicles. That it doesn't respond when you've got jumpers on there is also telling. Jan 19, 2017 at 17:45
  • Got the battery tested, it failed the State of Health and was replaced under warranty (only 21 months old).
    – tlhIngan
    Jan 20, 2017 at 1:02
  • have you checked for draw?
    – Ben
    Jan 21, 2017 at 1:51

2 Answers 2


It drained the battery because, on most cars now, the turn signal will illuminate the side or marker lights on that side when the ignition is off and the keys are removed. You probably need to thoroughly charge the battery slowly, and check the age - if it is old it may have killed it.


I don't think the turn signal was the issue. Normally the turn signal is on the ACC/power side of the electrical system and doesn't receive power unless the key is in and you are at least at ACC. The headlights/flashers... are direct connections that don't go through the keyswitch. The buzz you are hearing is likely the relay switches not having enough power to completely throw so they are vibrating. If the headlights and horn don't work, either there is a connection fault - corroded cable, loose cable... - or you have one or more cells in the battery that went out. If the headlights and horn don't work while you have the external battery hooked up, then most likely cabling.

  • As I pointed out, most cars have a "parking light" function linked to the indicator stalk.
    – Solar Mike
    Jan 19, 2017 at 20:55
  • So you're thinking it was a combo stalk - turn signal and headlight functions combined. If you left the lights on, that would definitely kill the battery on older cars. The one nice thing about the newer cars where the ECU controls everything is that it will shut off the lights by itself. Otherwise, I really hate that even the door switch and overhead and courtesy lights - everything goes through the ECU. Jan 20, 2017 at 9:06

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .