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'03 Pontiac Vibe - Dead battery only in the morning

I recently woke up to a dead battery in my Vibe. Got it jumped, started right up and drove to work. 10hrs later after work I jumped in and it started right up. No problem. Replaced the battery on the way home and ran some errands before coming home. Next morning, (9hrs later) the new battery was dead. Again, it jump started easily. This has continued for five days now. One key observation is that each day, the moment I connect the jumper cables, the headlights illuminate, but the light switch is in the off position. When I park the car the lights are not on and the switch is in the off position. At no point have I observed the lights coming on at night. Why would they come on in the morning before the key is even in the ignition? It also seems strange that the problem only occurs in the morning. Not once in five days has it even struggled to start during the day. I don’t even hear clicking in the morning. Is this a clue?

I looked at the wiring diagram for your headlight circuit. And if this only happens at night, then the problem might be that the ambient light sensor that sends it’s signal to the Daytime Running Lights module is causing the DRL’s to come on during the night.


This is my suspicion as well. I left out one detail… at dawn, when I’m driving to work, the brightness of my interiors has been switching a lot (controlled by this sensor as well I assume). It’s always been a little erratic in in-between lighting though so I wasn’t sure. I left this detail out of my original post to see if there were any other ideas. Tonight I’m thinking of leaving the fuse out for the head lamps. Replacing a fuse is a little easier than jumping it, although I really want to see the lights turn on at night on their own. Thanks Tester!

Could also be a sticky relay in the light circuit.

I’m assuming in the process of replacing the battery, the connections were thoroughly cleaned. If not, that’s the first thing to do.

Next up: If you can find that sensor, put a piece of duct tape over it to make it seem like it is night, and see if the lights turn on by themselves when they shouldn’t.

If not, ask your mechanic to do an “everything off” current test, see how much battey current is being used when everything is off. Anything over 50 mA would be suspicious, and anything over 100 mA means there is something in the car’s circuitry drawing currrent that shouldn’t be. At that point, you have to go through each circuit one by one, pulling fuses. Aftermarket items like audio systems and alarms would be the main suspects.

Pulled the fuse for the headlights last night and replaced it this morning and she started right up. When I replaced the fuse (before starting) the lights did not come on. Stopped to get coffee, turned off the car, when I returned the lights were on switch was off. I went to work early this morning in the dark. I noticed that the interiors were switching from dim to bright frequently. This was mostly occurring when I used my turn signal. My head light switch is also found on my turn signal. Another clue?

Again: sticky headlight control relay.

OK circuitsmith I’m checking the relay tonight. I think. Replacement relay costs $100+. There is an identical relay in my fuse box, but the manual doesn’t say what it’s for. I’m using it as a dimmer relay tonight. Lets hope the absence of the mystery relay does not affect the outcome of the experiment.
More internet research has revealed people reporting that this only happens when it is really cold. I tend to think that all Vibe owners north of me would have been reporting this issue long ago if it were actually related to the temperature. Although, I can’t dismiss the fact that my problem started on the coldest night in two years though. Anyone have temperature related theories?

It’s not a sticky relay. If it were the headlights would remain on when the headlight switch was turned off. Once the contacts in the relay opens and turns the headlights off, there’s no way power can get to the headlights. Unless something is commanding the relay to close the contacts. IE: ambient light sensor/DRL module.


Yeah, my poor description.
Sticky/flaky relay/module.

I found another relay in the fuse box that is the same as the dimmer relay. Problem is, I don’t know what it does. I pulled it and replaced the dimmer relay with it leaving it’s original slot open. This morning I put the relays back in their spots and the car started up-no dead battery. Now that I’ve read that others experienced this problem only during cold weather I’m not sure whether this was a function of the relay or the warm temperatures last night? OR removing the mystery relay. I played around today and got access to the ALS so I can unplug it when I’m ready. The weather is cooperating for experimenting, so I’m going to leave everything normal the next 2-3 nights (Lows of 43F, 27F, 16F) and observe the effect of temperature. The three mornings of dead battery before I started pulling the headlight fuse followed low temps of 17F, 12F and 9F.

Also I stopped by the GM dealer today to find out what the mystery relay is. They don’t know either. They said I should try the Toyota dealer. I get why, I know the car is engineered by Toyota, but have a little pride in your service guys. Go in the back and call Toyota if necessary. After considerable coaxing they confirmed that the ALS just pops up out if you pry. I now know I can replace the ALS ($185) but they think it’s DRL. After the temperature experiment, I’ll experiment with unplugging the ASL at night. If neither temp. or the ALS seem to be the problem, I guess it will be time to look for a DRL module. In the meantime, I’ll swing by the Toyota dealer and find out what the mystery relay is. I wish I had access to a new Toyota to borrow it and swing by the GM dealer to thank them for sending me to the Toyota dealer.

@Tkish hopefully the Toyota guys don’t send you to the GM dealer because it’s a Pontiac!


There is an old service bulletin for this. It states to replace the headlight switch.

Remove the steering column cover and unplug the headlight switch overnight and see if the lights still drain the battery.

The dimmer relay is in the middle of the engine room relay box, the other relay of the same size is at the edge of box labeled “Head” for headlight.

Nevada… you’re right that the mystery relay is labeled ‘head’ However having the headlamp dimmer relay, headlamp main fuse, Rheadlamp fuse, Lheadlamp fuse, I’m left to wonder 'Head’light what? and the fact that ‘head’ might mean headlight is why I have doubt about the relay solution I described above.