Weird car issue

Factual Questions
1

I’ll probably be getting it towed to the mechanic tomorrow, but I’m still curious. This evening, I got in my car and tried to start it… and nothing. It doesn’t even sound like it’s trying to start. Now, normally, that’d mean a dead battery, right? And the battery light is lit on the dashboard. But the headlights still work, and the interior light, and the power windows. I tried turning the headlights off, in case the battery was just too low to do both at once, and still nothing.

What would be causing this?

2

I am not a mechanic but my guess would be the starter motor died.

ETA: Check to see if there is a fuse for the starter motor in your fuse box. See if the fuse is blown (I think different cars may have the fuse elsewhere by the starter). It’s worth a look though. Easy to check and may save you a lot of money. If that’s not it only lost a few minutes looking.

This may be worth a watch:

3

It probably wouldn’t hurt to cycle through the gears, if you can, to make sure it’s in park.

4

Bad connection of the positive cable from your battery TO the starter, but AT the starter itself??

I like this one, too.

5

It could still be a dead battery. The battery might not have enough oomph left in it to engage the starter solenoid. Usually the car will click repeatedly when you try to start it (the clicking is the weak solenoid trying to engage), but sometimes not.

Some other possibilities, though these won’t usually cause the battery light to come on:

Give the starter a good whack with a broom handle or a baseball bat or something similar. If it starts then you’ve got a bad spot in the starter and it should be replaced.

There should also (probably) be a button to override the gear shift safety switch that makes sure you are in park before allowing the car to start. If you push that button and the car starts, then it’s just the shift inhibit solenoid that needs to be replaced. The location of the override switch varies (if your car even has one - some don’t). Check your user’s manual, or ask Mr. Google for its location.

Your ignition switch might have gone bad.

If your car has a starter relay (many don’t), then that relay might be bad or stuck. Mr. Google can probably tell you if you do, and where it is on your specific car. Give the relay a good whack with your hand. If your car starts then the relay got stuck, which is usually a sign that the relay is starting to fail.

I’m thinking the battery light is on just because the alternator isn’t putting out any juice, because the engine isn’t running. I don’t think it’s a symptom of your problem, though it might be.

ETA: Do the headlights dim when you try to start or do they stay the same brightness?

6

It’s a 2005 Camry. I found a video online showing where the fuses are, but I don’t know how to check if they’re good… Just pull them out and stick them on an ohmmeter?

Tried that already.

I think I probably would have noticed if they did (I couldn’t tell that anything was happening), but I wasn’t specifically looking for that.

7

How old in the battery? More than 4 years old? Replace it. A dead battery can still run all of the interior stuff, yet not be able to start the car. Most batteries are just to start the car. After that everything runs on alternator power.

8

Yep. It’s easy if your meter has a continuity checker that beeps. Just put the leads on either side of the fuse and listen for the beep. You don’t need to measure the exact resistance. Fuses tend to go completely when they go.

Many fuses have a visible link inside of them, so you can often see if they are blown just by looking at them.

9

I never knew car repair was so technically complicated.

10

It’s called “percussive maintenance”.

11

3 years, and it’s not just the interior stuff; it’s the headlights, too.

12

AFAIK, all cars have a starter relay, but it’s bolted onto the starter itself these days.
When you “whack” the starter, it’s the relay that you are trying to unstick.

13

That reminded me of one of Click and Clack’s frequent answers for this problem back when they were still on NPR – the neutral safety switch, in other words the switch that won’t let the car start if it’s not in park or neutral. Did you try seeing if it will start in neutral instead of park? Or try pushing the gearshift further into park.

14

The first thing I would do is take the battery somewhere and have it tested.

15

FWIW, I had a similar problem a few months ago, except that there was no power whatsoever – not even the interior lights would turn on. The car had been sitting for a few days, but the battery was almost brand new.

I was certain that it was premature failure of a new battery, which can sometimes happen, but the mechanic said it was a partially failing alternator and showed me a chart with little squiggles that were supposed to indicate it was only putting out power about half the time. I was so insistent that they ended up playing it safe and replacing both the alternator and also the battery which was still under warranty. I haven’t had a problem since.

The point of the story is that it can be hard to distinguish between a battery problem and an alternator problem without running diagnostics in an auto shop as they tend to have similar symptoms.

You might consider getting a boost instead of towing, but that’s a bit of a risk if the alternator has failed.

16

Well, a failing alternator won’t charge the battery, so the battery ends up getting drained as a result.

They tend to put as small of a battery in a car as they can get away with, which is why they die after only a few years. Put in a larger battery (the most cranking amps you can get that still fits in your vehicle, space is usually limited) and the battery will last for 15 to 20 years, easy.

You don’t need a fancy auto-shop computer for most alternator failures. Measure the battery with a voltmeter. It should be somewhere around 12.6 volts if fully charged, a bit less if it’s been drained. Below 12 volts is really bad and the battery might not fully recover when re-charged. When you start the car (might require a jump if the battery is drained), the voltage should go up by a volt or two. If the voltage doesn’t go up, then the alternator isn’t working.

If you jump it from another car and let it charge for a bit, you should have enough battery power to drive it to a shop to get the alternator replaced, assuming you don’t live way out in the sticks and have a 45 minute drive to town or something like that. Turning on the headlights will rapidly drain the battery though. It’s best to do this during the day if possible.

A lead acid battery is made up of two sets of plates. In each “cell”, one plate is lead and the other is lead oxide. There’s a mixture of water and sulfuric acid in between the plates, which acts as the electrolyte. As the battery discharges, both plates turn into lead sulfate, and the sulfuric acid turns into water. Each cell puts out a bit over 2 volts. There are therefore 6 cells in a car battery for a bit over 12 volts fully charged (6x2=12).

More surface area on the plates gives you more cranking amps. Thicker plates gives you a longer discharge time. For a given amount of lead, you can either have thinner plates with more surface area for higher cranking amps or you can have thicker plates that can crank for longer but have less cranking amps. Car batteries tend to have very thin plates, so they put out a lot of cranking amps to start the car but they don’t last very long if you keep cranking. “Deep cycle” batteries have thicker plates.

If the battery gets discharged too far, the lead sulfate forms hard crystals that don’t break up during recharging, causing a permanent loss of capacity for those part of the battery plates. If the battery has been discharged to the point where the interior lights won’t even turn on, the plates are probably heavily sulfated and the battery is shot.

You were wise to get it replaced.

This is also why the undersized batteries they put in cars these days (to save weight and money) only last a few years. They tend to get discharged too far just through normal use and permanent sulfate crystals build up on the batteries. Putting in a larger battery so that it never gets discharged far enough for permanent sulfate crystals to form solves the issue.

17

My truck has been acting up in a similar manner. I’ve got a stick shift and I think the clutch pedal switch is the culprit. I need to really press the pedal down allll the way to start the truck. Or hit the clutch disengage button, which is much easier, but is not part of my truck starting autopilot.

18

But in every car I’ve owned in the last 15 years, this is physically impossible because the engine compartment doesn’t leave enough room for any battery of greater dimensions than the original.

I guess running long cables from the trunk would allow that, but then you’d have to hillbilly up something to restrain and cover the battery. And giving up cargo capacity for a longer life battery isn’t always a viable tradeoff.

19

Exactly.

I read ecg’s point not as “Owners should retrofit larger batteries.”

But rather that “Car manufacturers are designing in too-small batteries to save weight and space. Which is good for car sales but bad for battery longevity.”

20

I used to keep a rubber mallet in my RX-7 for just this purpose. Once it got to the point where I had to crawl under that and pound on the starter more than 50% of the time, I bit the bullet and bought a new unit.

That’s also the time where I learned a valuable lesson. Look in the box at the part the NAPA guys gave you before you remove the old part.