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okay, back in 2017 my 300 got hit on the front driverside by a drunk driver and ever since, every battery i put in it, the car destroys the battery after being connected for more tham 2 hours. it use to start up last winter but now all it does is show dash lights and does nothing (doesnt start/click/try to turn over) when i hit the brakes the headlights turn on as well with the brake lights. ive checked all fuses and they are all good but i keep having problems with it. can somebody please help me?
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2006 Chrysler 300c SRT8 w/ a Hellcat Supercharger
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It sounds like a short in your wiring harness. You probably have a few cut wires from the initial accident that are touching the frame or a ground. There should be a master fuse to prevent this thing from killing your ecu. Was the car repaired at a garage? How significant was the damage?
 

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Giving elec advice on forums are a minefield, as if you keep it basic, person misunderstands, damages car = your fault you are the bad guy.

Give complete details, (and there are a lot/can be complicated) "raves on, war and peace, loves the sound of own voice, get to the point." Then you get all the people who "aren't electricians/electronics techs; but...." (then want to argue). So, you end up giving up = delete comments because "not worth the hassle".

So I will try to aim for middle ground. Here goes.

I concur with below, ie impact damage on the loom.

Given how many wires there are in the looms, can be a huge problem.

Electrically, you can measure the current drain and see if it is draining the battery more than normal. There will be SOMEONE on here who has measured the normal current drain with ign off; that is, the only current being drawn is the vehicle security/alarm system. That runs for days/weeks without flattening battery, so is miniscule.

To do that you have to know how to measure current with a multimeter. MOST people ONLY measure voltage, and don't understand "current - measure in series" (in line) and MUST have a meter that can handle it (in this case up to ten amps capacity for the drain you are saying, ie battery flat in 2 hours). If you don't understand measuring current in series; find a mate who does; as unless people understand, they'll normally end up with a blown meter/loom damage. I can explain, but long winded, and very easy to damage stuff, hence why many don't do it/try and explain it. ONLY measure the normal current in series (in line) NOT to earth or negative. That will create a short and burn loom/blow up meter. Again, if not sure what I mean, don't do it. (Sorry for the "suck eggs"; ;-) just don't want any damage to your car.)

Once you have found you have excess current drain (99% chance you will); there are two ways to find the problem.

The electronic way is to use some form of line tracer (chirper) which can find current paths; but only elec techs will have those; and under a bonnet can be ambiguous. Although for a good tech, a substantial current like that should have some indications with decent diagnostic gear.

The "hands on" way is to trace the loom for signs of impact damage. It is likely the loom was "mashed" with impact damage and wires squashed together, hence the short. As corrosion makes the wires degrade, that corrosion can conduct, and the problems slowly get worse.

This isn't always practical, as the loom is often hidden/behind panels/unaccessible; but to be repaired, you either have to find it/repair it; or replace it, so have to inspect it all anyway.

These looms are very complicated/complex to the average person, go everywhere, and any shorts (either existing or while testing) can fry expensive computer components in the car.

I do all this stuff myself (used to work on warship combat systems and everything that hung off them, so similar but a lot more of it - imagine intermittent faults on a 20 year old warship loom :) ); but most people are better taking it to someone. The problem is, most "shops" are mechanics first and "elec second" and just "plug it in = do what computer says" so you need an auto elec who knows their stuff.

Even many elec techs will just "replace the loom" as even twisting it to test could make the short worse/do damage while they are testing, and a risk for them of further damage.

I hope that helps and doesn't just confuse more.
 
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