Battery negative earth lead

[Ingwe]

I can't get out to our van to look but am following a thread about getting the remote fob to work again by disconnecting the negative earth lead and touching it to the positive terminal. This sounds wrong to me intuitively but I then got confused as I don't recall there being a secondary earth lead attached to the battery negative terminal. Is there also a positive earth lead? I'd be grateful if someone could post a picture showing the negative earth lead.
Many thanks.

 

[poppycamper]

I can't get out to our van to look but am following g a thread about getting the remote fob to work again by disconnecting the negative earth lead and touching it to the positive terminal. This sounds wrong to me intuitively but I then got confused as I don't recall there being a secondary earth lead attached to the battery negative terminal. Is there also a positive earth lead? I'd be grateful if someone could post a picture showing the negative earth lead.
Many thanks.

Don't fully understand your question. Do you mean van battery...
Certainly does not sit correctly with me...

 

[Two on Tour]

Any mention about sacrificing a goat on an alter as well ?

 

[Ingwe]

Don't fully understand your question. Do you mean van battery...
Certainly does not sit correctly with me...

Yes, I'm referring to the van (cab) battery. As I read the suggested advice, it is not touching the negative battery lead to the positive lead but the negative earth lead only being touched to the positive terminal for 10 seconds. Ostensibly, this dissipates static charge in the cable, said to be the cause of problems with remote central locking using the key fob.

 

[Landy Andy]

I’ve heard of this on many vehicles before to remove all power in the system. But I would be very cautious in a motorhome with many power sources that may be attached together at some point.

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[Jev88]

How about a jump lead from negative terminal to a metal spike in ground for a few seconds.

 

[ambulancekidd]

Might work on an ordinary vehicle, but as Landy Andy says, you have too many other power sources in a motorhome & you could cause very serious or dangerous damage to all sorts of systems & thats not to mention fire risk.
That'd take a lot of explaining to an insurance company & me thinks they might giggle as they walk away without paying.

 

[Landy Andy]

If you join the two connections with a wire with bulb and bulb holder in them then it will either use up the power that is within the system or brightly glow, telling you that it was a good thing not just to short them.

Just an idea.

 

[XxAnthxX]

I believe the trick to reset the electronics and body computers by draining any capacitors is to disconnect both leads from the battery and THEN touch them together for a few minutes.......whilst both OFF the battery, or you may end up with bonfire night early

This is what I was shown when I had the T5.....

[Guide] Full Van ECU Reset (Capacitive Discharge) -- How I Done It --

Full Van ECU Reset (Capacitive Discharge) -- How I Done It -- The T6 is full of ECU`s, Modules, CAN Buses and Data packets . . . . . Just like your Phone or PC right. The motor vehicle industry has spent years with research and development making the modern car/van Data and electrical system...

www.t6forum.com

I would isolate any B2B, solar and leisure battery too.....

 

[SandraL]

Note, if you have solar charging or trickle charge from leisure batt to maintain the starter batt you would be shorting out these supplies as well unless you disconnect them first.

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[Sandancers]

I thought of loads of witty replies to the question. But in the end settled for this one.

DON'T DO IT !

 

[pappajohn]

Touching ANY Neg wire to Pos battery terminal, or anything live, with the main earth still connected to the battery is the vehicle equivalent of seeing if you can breath underwater.... Only an idiot would do it.
It's simply a dead short circuit.

 

[Wildweasle]

I can't get out to our van to look but am following a thread about getting the remote fob to work again by disconnecting the negative earth lead and touching it to the positive terminal. This sounds wrong to me intuitively but I then got confused as I don't recall there being a secondary earth lead attached to the battery negative terminal. Is there also a positive earth lead? I'd be grateful if someone could post a picture showing the negative earth lead.
Many thanks.

NO, electricity has always been an anathema to me, unless you understand it, leave it to one who does !!

 

[chaser]

If you join the battery terminals together for ten seconds, you will probably need a new battery and I wouldn't hold the cable while you are doing it else you will need some new fingers.
Havnt you ever touched them together accedentily .

 

[Landy Andy]

joining the two battery terminals together isn’t what has been suggest though. It’s the neg wire that has been removed from the neg terminal of the battery. I’m not saying that is what I would do, I’m just correcting the thread.

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[Badknee]

Seeing as I’m an old fart, in the dim and distant past I remember you used to change the earth from + earth to -earth by flashing the pos and neg leads on the back of the dynamo................ I told you I was old

 

[SuperMike]

I doubt the cable would last ten seconds, or that you could even hold it as it heated up.

 

[PeteH]

If you join the battery terminals together for ten seconds, you will probably need a new battery and I wouldn't hold the cable while you are doing it else you will need some new fingers.
Havnt you ever touched them together accedentily .

Not to mention, the Explosion, and the Battery acid flying everywhere.

IF you remove the battery and any other form of power supply. (solar comes to mind) "Earthing" the the cable system might allow any capacitors to discharge?. If there is any power source at all it will otherwise (as John said) be a dead short circuit, and likely to fry half the vans electrics and yourself too.

 

[dunnah01]

If you disconnect the negative lead from the leisure battery(s) first and then disconnect the starter negative and touch it to the positive starter battery for 15-30 secs you will be fine although it often won't clear codes but worth a try.

 

[TheBig1]

If you wan't to believe silly things suggested on the internet, then budget for new airbags when you try shorting leads, The capacitive discharge is sufficient to trigger the airbags if you don't follow the correct procedure. Disconnect the battery negative terminal and move the lead away from the battery post.............................. Then wait about 30 minutes to allow for the capacitors to self discharge, with no need to short the ECU and BCM

Far too many electronics on a modern vehicle that can be damaged

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[Ingwe]

If you join the battery terminals together for ten seconds, you will probably need a new battery and I wouldn't hold the cable while you are doing it else you will need some new fingers.
Havnt you ever touched them together accedentily .

This isn't what I was proposing. But thanks for the warning.

 

[chaser]

Seeing as I’m an old fart, in the dim and distant past I remember you used to change the earth from + earth to -earth by flashing the pos and neg leads on the back of the dynamo................ I told you I was old

Yeah we do this regular with old tractors with dyanamo and control box.

 

[poppycamper]

This isn't what I was proposing. But thanks for the warning.

"Disconnecting the negative earth lead and connecting it to positive terminal" !!! Sounds to me that is exactly what you were proposing

 

[dunnah01]

"Disconnecting the negative earth lead and connecting it to positive terminal" !!! Sounds to me that is exactly what you were proposing

I think you're confusing connecting negative lead which is fine, with connecting negative terminal which would be good for fireworks

 

[poppycamper]

I think you're confusing connecting negative lead which is fine, with connecting negative terminal which would7 be good for fireworks

Yes i am confused... surely negative is negative wether it is the negative lead or terminal??
This thread really to me does not make any sense and I would say that I do (to a point) understand basic 12v circuits.

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[XxAnthxX]

Yes i am confused... surely negative is negative wether it is the negative lead or terminal??
This thread really to me does not make any sense and I would say that I do (to a point) understand basic 12v circuits.

The method is to completely disconnect both leads from the battery terminals so there is no power source involved.

Then touch the two leads together......nothing to do with the battery terminals.

Have a look at the video in my earlier post....It was an RAC man that showed me, quite a few years ago when I had my T5.

 

[Jamesh]

I'd suggest putting a bulb across the terminals so that you aren't discharging the circuit in an uncontrolled short but rather through a energy dump that is a bulb.

Cheers James

 

[Deneb]

The "idea" is to disconnect both the positive and negative cables from the battery and touch the ends of both together NOT to do it with the battery still in circuit. It's a generic internet fable though, and Fiat, Peugeot and Citroen publish a different procedure for the vans. Other vehicles may also have differing but specific procedures.
For Sevel vans, there is a specific safety procedure to be followed before disconnecting the battery cables, to prevent the risk of corruption to ECU memory, which involves ensuring that the vehicle network is in sleep mode before starting.
I'm not at home at present so don't have access to the file but I've posted it here before.
There can be complications on MHs if there are connections between hab and vehicle battery circuits, e g. solar with vehicle battery trickle charge etc
Basically, you need to be inside the vehicle with all doors shut, ignition off and key removed. Wait at least 10 minutes since achieving that state to allow the vehicle to enter sleep mode before disconnecting the negative lead without opening any doors. Once that's done you can open a door and work from outside if necessary. To reset the BCU, also disconnect the positive battery cable and wait at least 3 minutes before reconnecting the battery, again with all doors shut. Put the headlight switch to its on position before energising the ignition, wait 10 seconds then check all electrical devices and lights.

 

[Jaws]

Reading the OP, I can see the logic but would be wary.
I would proceed thus:
Disconnect the neg lead from the cab battery AND the had batteries
Either cover the solar panels if fitted or do the job when it gets dark
With all the neg feeds disconnected and no voltage what so ever in any circuits it will now be safe to touch the neg lead on the pos. terminal of the cab battery for 10 seconds thereby dissipating any and all residual voltage.

Do be aware that if your cab radio is coded you will have to re-enter the code so make sure you have not only the code but how to enter it to hand, else the whole exercise could be expensive !

 

[Reallyretired]

Seeing as I’m an old fart, in the dim and distant past I remember you used to change the earth from + earth to -earth by flashing the pos and neg leads on the back of the dynamo................ I told you I was old

Being also an old farte I did this on one +earth car so I could fit a -earth cassette player. Repolarised the dynamo and turned the battery round, a couple of minutes job.

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