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Discussion Starter #1
All, I am moving this discussion over from ChallengerTalk and starting its own new thread here. To continue:

I have a 2019 Charger SXT (basically same a Challenger and 300). I bought it new last April, and since my first weekend of ownership, there has been a loud “THUMP" or "WHUMP" from underneath the car about every 5-10 starts. It is super intermittent, and I cannot discern a pattern. It definitely is not coming from the front. Imagine someone underneath the car or in the trunk hitting the structure with a big rubber hammer - one big, solitary THUMP!

It may go a week without doing it, or it may do it two-three times in one day. One thing it has never done is thump first thing in the morning while cold, but it will do it on a cold start in the afternoon. It is more likely to happen, I think, when the car is warm after having been run but not exclusively. The first time it happened, I thought someone next to me had slammed their door really hard.

My first thought was the exhaust was hitting the bottom of the car. I took it to my dealer twice and was told there are no interferences. I was able to get it to do it once in the presence of a service advisor. I left it over a weekend, and he said his techs were able to duplicate it, and it was coming from the stereo because of a voltage spike. It really did not sound like this to me, but my car does have the premium Alpine stereo, and frequently it does sound like it is coming from the subwoofer area. I was told there was an upcoming software upgrade that would fix the problem.

A couple of weeks ago, my dealer installed a software update, and it has made no difference whatsoever.

Some have suggested a backfire. Maybe it is, but it does not sound exactly like one, and I frequently start the car from outside using remote start, and every start from outside the cabin sounds perfect.

Oh, well, I’m not letting this drop. I really believe the dealer does not know what to do, because they have no guidance from FCA. I have bought the factory service manual, and it gives no guidance in this area at all. If it is a radio/stereo problem, the only advice given is to simply replace the faulty parts. There is not much diagnostic guidance given. I have recommended to the dealer to consider replacing either the head unit, amplifier, subwoofer - anything to narrow this down (if it is stereo-related).

I spoke to two other Dodge dealers in an adjoining state, and they had never heard of this problem, either. I’m not sure FCA is onto this problem at all, but I have opened up TWO cases, the latest with a Dodge Cares rep who contacted me on the ChallengerTalk forum. Both my cases were closed with no resolution and with no notification to me they had been closed. I had to contact them to find out the status of the cases. The only "help" offered by Dodge Cares was to tell me contact my dealer, who is not motivated to run this down but did tell me to contact Dodge Cares, who tells me to contact the dealer, who tells me to contact... Well, you get the idea.

My dealer says they have never heard of this problem before, and that's likely true, but the existence of the ChallengerTalk thread shows we are not alone in this. Unfortunately, I feel like FCA has left it in the hands of its customers to figure this problem out, even as the cars are still under full warranty.

If I get any kind of path forward from anyone, I will post here. Please weigh in.
 

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If the sound is cause by a current spike, unplug the sub for a while. If the audio system has capacitor discharge them and unplug them for a while. If there is no current in the sub it should not move and should not make sound. Unless there have some mechanical problem. And the only way I can think of would be due to temperature deformation and / or pressure. Like the sub would expand or retract, get stuck. And after warming up release and the membrane would hit and make a sound like a drum. In any case this is not normal and you should document every thing in case you decide to go in court if they can't solve it.
 

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Discussion Starter #3
On another forum, one member wrote that his Charger Rallye did the exact same thing mine is doing. He said he removed the subwoofer and found the connections on the back loose from the factory. Attaching them correctly, he never had the thump problem again. Today, I dropped my car off at the dealer to have the rear differential replaced because of a whine (yes, really). I asked them to check the subwoofer connections while it is there. If they find nothing, pulling the subwoofer fuse is my next resort.
 

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Discussion Starter #5
Wow bad diff already o_O that suck... but mistake do happens on the chain. Let us know if the noise got fix.
Will do. I'm not hopeful a loose connection is the problem.

Yeah, the diff noise is classic ring and pinion whine, not bearing noise. The car was delivered to me from new with it, and I noted it during my first road trip. Whine at 60-70 MPH at light to moderate throttle application or when going uphill, basically anytime the engine is sending a bunch or torque to the rear diff. We'll see if the dealer can fix that one, too. I was initially told they would put a whole new diff in. Yesterday, they told me they would have to tear into the old one and estimate the repair cost. They will now only give me a new one if repair costs exceed 70% of just buying a new one.
 
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