Author Topic: Battery going flat/ key fob issue?  (Read 4636 times)

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Offline Morgs

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Battery going flat/ key fob issue?
« on: June 22, 2020, 08:51:56 am »
Hi all,

Hoping someone can help, this is driving me mad.

I've had my Mazda 6 for a little over a year, and always driven it every day without problems. It sat for the first week of lockdown, and when I went to use it the battery was flat. I charged it up, took the car out as normal, two days later it was flat again. Now it's going flat all the time. Nothing is being left switched on.

The alternator is fine, I've taken it for a fifty mile run to make sure it got a good charge. It ran fine, then two days later after sitting it was flat again. I've had the local garage test the battery and that's also fine (I replaced it when I got the car as the original battery was duff - now I'm thinking maybe this problem existed when I got the car and showed up while it was sitting, and I've just never realised since due to using it every day).

One thing I have noticed is that the ignition is not lighting up green to show it detects the key, it stays red. However, when connected to the starter pack, the car will start, even with the light red. The key fob battery is fine I think - I changed it just before COVID lockdown, it locks and unlocks the car fine, detects when you take it out of the cabin with the car running etc. I know zero about keyless ignition.

Has anyone experienced anything similar or got any thoughts? I really don't want to have to take it to Mazda as I've lost all my work due to COVID but I'm ripping my hair out with it.

Thanks!

Morgs

Offline saddler5

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Re: Battery going flat/ key fob issue?
« Reply #1 on: June 22, 2020, 12:32:17 pm »
I had the same model as you previously and had similar problems which turned out to be a corroded earth connection under the wing (there are a number of posts on here about it). When connected to a diagnostic tool, this can randomly throw up various faults including flat battery in key fob, faulty interior intrusion sensor and  steering column.
If the battery in the key fob is flat, you should still be able to start the car by pushing the stop/start button in with the tip of the fob.
I don't know whereabouts you are based but there may be an independent Mazda specialist near you who could sort this. As far as I am aware, Mazda have previously issued a Technical Service Bulletin about this problem.

Offline Morgs

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Re: Battery going flat/ key fob issue?
« Reply #2 on: June 24, 2020, 01:52:29 pm »
Oh that's helpful, thank you.

It's the actual car battery that's going flat - but it's weird that, when attached to jump leads or a starter pack, it will start even though the start button is showing red.

I've not been able to find anything specific on the corroded earth connection here or online, but I'm going to message my nearest Mazda dealer and ask if I can get a copy of the Technical Services Bulletin. I'll let you know how I get on.

Offline Morgs

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  • Year: 2010
Re: Battery going flat/ key fob issue?
« Reply #3 on: July 12, 2020, 10:06:27 am »
UPDATE

Fixed.

It was literally just corrosion on the thread of the bolt (negative battery terminal to chassis). You couldn't see this from the top, bolt looked mint).

Bolt taken out, thread cleaned, bolt reinserted, problem gone away. That's a very bad earth point!

Offline aymeric

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Re: Battery going flat/ key fob issue?
« Reply #4 on: August 11, 2021, 09:35:32 pm »
thanks for posting the update,will check mine tomorrow.