Battery Disconnect procedures

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Fri, 17/03/2023 - 13:49
Jdring
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Location: South of Oxford, UK. 87' 230GE SWB Manual, 89' 230GE SWB Auto, 2012 G350Bluetec LWB
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Interesting problem! At 10pm my horn on G350 CDi decided to blast away on its own. Intermittent, 10secs, 2secs, 1sec, blip, 5 secs etc. Random. no flashing lights. Not alarm. Car would unlock and lock and start but not stop - horn continued. I came to the conclusion it was a stuck/short circuit on the steering wheel centre push. It made sense a bit because I had used the horn once 2 hrs previously to say hi to another vehicle! Anyway, as it was the night, in a built up area, I decided to disconnect the battery (negative pole) to avoid a repeat performance. And re-visit in the morning. The G350 has an auxilliary battery, I've had not alerts about it, and so I assumed all ECU and even some courtesy power would remain. But all power is cut immediately and in the morning on restoring the battery all resumes but the trip, clock etc is wiped. So I am assuming I have to do some setup: Clock etc. Gearbox retrain? Anything else? Will ECU programming be removed? Why didn't the Aux battery hold up all this? (I have a new one waiting to go in). Anything else that happens with a battery disconnect? It's a new battery also...and nothing reset when that was replaced. Presumably because it was done within a minute or so. (as an aside, I had an AA man jumpstart a Fiat 500 and that managed to blow the Bluetooth module!) Views?
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Mon, 20/03/2023 - 02:32
#1
gooch
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Re: Battery Disconnect procedures

 

 

Jdring wrote:
Interesting problem! At 10pm my horn on G350 CDi decided to blast away on its own. Intermittent, 10secs, 2secs, 1sec, blip, 5 secs etc. Random. no flashing lights. Not alarm. Car would unlock and lock and start but not stop - horn continued. I came to the conclusion it was a stuck/short circuit on the steering wheel centre push. It made sense a bit because I had used the horn once 2 hrs previously to say hi to another vehicle! Anyway, as it was the night, in a built up area, I decided to disconnect the battery (negative pole) to avoid a repeat performance. And re-visit in the morning. The G350 has an auxilliary battery, I've had not alerts about it, and so I assumed all ECU and even some courtesy power would remain. But all power is cut immediately and in the morning on restoring the battery all resumes but the trip, clock etc is wiped. So I am assuming I have to do some setup: Clock etc. Gearbox retrain? Anything else? Will ECU programming be removed? Why didn't the Aux battery hold up all this? (I have a new one waiting to go in). Anything else that happens with a battery disconnect? It's a new battery also...and nothing reset when that was replaced. Presumably because it was done within a minute or so. (as an aside, I had an AA man jumpstart a Fiat 500 and that managed to blow the Bluetooth module!) Views?


hi John

Hope your well

I joined the G350d 64' plate club too last month hooooray. I hope mine dont do that!

I personally believe losing the Aux Battery power will erase any ECU proggraming that may have been installed after factory installation. It happened on on my 110 defender with better torque and bhp increase by 'Alive' tuning.
 

Retrain the gearbox to AMG style lol 

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Mon, 20/03/2023 - 13:21
#2
Jdring
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Location: South of Oxford, UK. 87' 230GE SWB Manual, 89' 230GE SWB Auto, 2012 G350Bluetec LWB
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Re: Battery Disconnect procedures

I am happy to let the gearbox train itself.

Clock resets itself from the time signal on the radio channels.  Neat.

There is still plenty of responsiveness and power in the engine, so I think tuning is retained (in my case) and no indication that the Aux Battery failed.  But I was surprised that no courtesy lights remained on etc and had heard that the Aux battery might have enough juice to turn the engine - makes sense in a ruggest vehicle to have such backup but everything was dark - not even central locking retained which meant using the key to lock drivers door.

 

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Fri, 24/03/2023 - 15:18
#3
gooch
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Re: Battery Disconnect procedures

Jdring wrote:

I am happy to let the gearbox train itself.

Clock resets itself from the time signal on the radio channels.  Neat.

There is still plenty of responsiveness and power in the engine, so I think tuning is retained (in my case) and no indication that the Aux Battery failed.  But I was surprised that no courtesy lights remained on etc and had heard that the Aux battery might have enough juice to turn the engine - makes sense in a ruggest vehicle to have such backup but everything was dark - not even central locking retained which meant using the key to lock drivers door.

 

Hi mate

Its funny because I thought it was the earlier versions that only had battery drains!
Have you now replaced the main car battery and Aux too?

For eg. The G55 You saw at silverstone Had a small problem too.  

The battery would slowly die after if not used for good two weeks, I went on many forums as we do and many pointed to car not sleeping for many electric componenets. I strted with the Satnav/Command and it ended up being the issue. The unit used to swith on/off randomly when you opened the door first thing and sometimes took a while to get sound out of the speakers. I found a w203 version on ebay cheap in fine working and good condition. This somehow eliminated the issue.
 

Ie: alarm system, satnav, ecu front pasenger footwell area get wet from wiper spindles and water finds thier way to main engine ecu and fuse/relay area(common). Door kick plates not switching off, front/rear led lights malfunctioning allowing centre/ fusebox not to sleep. 
And Can bus wiring corrosion/ wires coming out of retain clips/boxes. 
 

The list goes on........

But there are many things that can trigger Slow drains I found on earlier ones, I am still learning about the new ones.

 

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Fri, 24/03/2023 - 19:32
#4
Jdring
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Location: South of Oxford, UK. 87' 230GE SWB Manual, 89' 230GE SWB Auto, 2012 G350Bluetec LWB
GWOA Groups: Committee, Members
Re: Battery Disconnect procedures

Fun and games.

Mine wasn't a battery drain at all though.  The horn was stuck on, and I needed to make sure it didn't come on in the middle of the night.  Hence the disconnect.  But it lead me to wonder just what the Aux battery is doing, if anything, because everying went off.

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