My Recent Car Episode and How I Could Have Wasted A Lot of Money on Nothing

The engine bay where my diagnosis journey started. The battery and one of the fuse boxes are in the back left compartment.

A couple months ago, I replaced my car with a nicer, newer one. Unfortunately, cars can have issues at any time – even early in life. And on one recent morning, when I went out to the garage, my car wouldn’t start. In fact, the dash wouldn’t even light up. The battery was 100% dead. Thankfully, I have AAA, so I was able to get someone out there within about half an hour to jump it.

As anyone who has bought a battery for a late model car already knows, batteries die all the time now. In a typical example of “progress” in action, what had been a $50 purchase that would last roughly a decade is now an often $150+ purchase that lasts about three years. The warranty period, of course, has adjusted to reflect this new reality and in my experience, batteries tend to survive just barely long enough to surpass it. The culprit, of course, is our obsession with putting more and more electronic crap in cars, including a significant amount that continues to draw when the car is turned off. Today’s batteries are actually much more powerful than the ones that used to cost so much less, but the demands on them are also much greater.

Anyway, I priced out batteries while I was waiting for AAA to show up and determined that NTB had the best offering for my car. Once the car had been jump started, I drove straight there. It was less than a ten minute drive, but interestingly enough, by the time I got there, the battery tested perfectly fine. It was still a little low, but it had more than enough juice to start the car. I discussed this with the manager, who ultimately advised me to test it again after driving a further distance I had planned for that day. He suspected that it may be the alternator. In the over 250k miles of driving I’ve done in my still relatively young life, I’ve never once had an alternator fail. And I would have been rather surprised to see it happen on a five year old car with well under 50k miles, but testing is free and my AAA membership would have taken care of me again if the battery died again, so I went on my way.

I drove around for the rest of the day without incident. Of course, this only deepened the mystery of how the battery had died. But that very evening, I had a lucky break that led me to the answer. I happened to leave something in the car after I had closed the garage so I went back out to get it. To my surprise, when the door was open, I discovered that the headlights were still on. Like any modern luxury car, my car has automatic headlights. So while the battery mystery was immediately solved, it also gave way to another one. Why weren’t the headlights turning off?

When trying to diagnose any car problem, you want to start with the simplest possible explanation. In the case of an electrical problem, that means checking any potentially applicable fuses, which I immediately did. But none of them were bad. So I was back to square one, although at least for the moment I knew I could keep the battery from dying by turning the headlights on and off manually. But I had a lot of other stuff that had to get done so I moved on from the car situation for the night.

The next morning, I thought more about the car as I sat in the sauna. I had realized something had been different for a few days, but I couldn’t put my finger on what. But in thinking about the automatic headlights not turning off, I realized what it was. The dome lights, which are inexplicably non LED and incredibly dim to begin with in this car, had not been coming on. And that’s when it came to me. The automatic headlights were working fine. The issue was that the car didn’t know the doors were being opened and closed! When I thought about it, the automatic adjusting windows, which open slightly when the doors are opened and then close when the doors are closed again, hadn’t been functioning normally either. Clearly I had found the problem. But how to fix it?

First, I went back to the fuses again, this time looking for any door specific ones. But again, none were bad. So I started looking very closely at the doors, checking to see if any wires looked damaged, etc. Everything looked ok. But there was one thing slightly – and I mean SLIGHTLY – out of place. This little guy.

Literally one screw that holds this thing on being slightly loose was causing all of these problems!

It was just slightly loose when I touched it. I didn’t know what it was, but I figured it had to be related to the door somehow due to its location in the door jamb. I tightened it up and VOILA! Suddenly everything worked correctly again. Apparently, the little thing is a sensor that compresses when the door is opened and decompresses when it is closed. And apparently it is very sensitive. So what lessons are there in this experience?

First and most importantly, don’t make assumptions with cars. There are way too many mechanics out there who will just start replacing parts that might solve the problem rather than first finding the exact diagnosis. This can be simple inexperience, but it can also be more sinister. After all, the more work they do, and the more marked up parts they replace, the more money they make. And there is really no way of holding them accountable for doing that aside from not coming back. Had I taken that approach in this case, I would have replaced a perfectly good battery for about $150 and been no better off than when I started. Then, when that didn’t work, I may even have replaced an alternator for considerably more than that. Thankfully, most auto parts stores are happy to help you with testing and even some advice, as the friendly folks at NTB were in my case.

Second, know your car and pay attention to it. While I am no electrician, had I been more observant, I could still have solved this pretty easily. I would have noticed the dome lights not coming on and the automatic adjusting windows not adjusting. At that point, I would already have known what the problem was and could have skipped straight to the last step of the process I just finished describing. Sadly, with as much as I have going on in my life, someone in a clown suit could probably be riding a giraffe through the parking lot of my apartment complex as I walked out to the garage and I’d say there’s at least a decent chance I wouldn’t notice anything unusual. In today’s world, I’m guessing I’m not alone in that.

Third, even in a world of incredibly complex cars with numerous computer modules and miles of wiring, the simplest solution is usually the right one. Yes, a bad battery would have been an easy explanation in this case – but not the correct one. That was in doubt as soon as I got to the auto parts store. In the end, it turned out to be a part so simple that cars have probably had them for as long as they’ve had dome lights that turn off when the doors open. And it wasn’t even bad – just slightly loose.

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