Tucson won't start, dash lights flashing

Earlier today my wife told me her 2016 Tucson 1.6 wouldn’t start and that all the lights on the dash were flashing when she tried. I tried it myself and the various indicators flashed, accompanied by a rhythmic “thumping.” The “BSD ON” indicator was lit and the hazard flashers came on by themselves. We’re going to have it towed to our regular mechanic tomorrow but in the meantime I’d appreciate any input/insight.

My first thought is a weak battery or bad connection.



Yeah, my first thought was a failed BCM but I’m holding out hope for a bad battery. Way cheaper that way.

We replace 20 to 30 batteries each week but no body computers. It has been 10 years since I replaced a BCM.


So what Nevada is saying is, It can’t happen.


Big mistake!


My take is, if it can happen it’ll happen to us. :man_facepalming: Still hoping for a bad battery but not holding my breath.

Do you own a simple voltmeter? It’s easy enough to check battery voltage while your wife is trying to start the car.

I have an old Radio Shack multimeter but I don’t know if it still works.

Then I’d leave it alone and let the shop look at it. The only thing worse than no information is wrong information.


All it takes is a 9V battery to see if the multimeter is working reasonably well.

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I’m guessing the problem is a simple one, weak battery. As a test OP might try charging it with a battery charger. Once this issue is resolved suggest to take photos/make notes on which dashboard lights turn on with key in “on” but engine not started, then what happens to dash lights after engine starts. I’m guessing the dash light symptoms are normal.

One puzzle , this weak battery theory doesn’t necessarily explain the rhythmic thumping sound. That could be the starter motor trying to crank the engine, failing, then retrying. Or it could be something which normally occurs but isn’t heard above the sound of the engine idling; ABS self- testing, HVAC doors moving around, etc.

I think that HVAC doors thrashing around are a real possibility. However, the ABS self-test requires the vehicle to be moving, and from the sound of things, this vehicle is currently not capable of moving under its own power.

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It was indeed the battery. My assumption regarding the thumping was the car attempting to start but I could easily be wrong. Thanks everyone.