Where Does The Battery Negative Cable on a Defender Hi 300tdi Attach Beneath The Vehicle ?

dogdog1 · Oct 27, 2023

Hi , as per the title . I have scoured the internet but can't find a clear answer to this . I have attached the cable to the gearbox crossmember top bolt using the first eyelet on the cable but I have no idea where the end of it attaches . And my gearbox is live !

marjon · Oct 27, 2023

dogdog1 said:
Hi , as per the title . I have scoured the internet but can't find a clear answer to this . I have attached the cable to the gearbox crossmember top bolt using the first eyelet on the cable but I have no idea where the end of it attaches . And my gearbox is live !

Anywhere on the chassis is good as long as its clean.
But sounds like you should connect it to the transferbox .

dogdog1 said:
And my gearbox is live !

What makes you think this? This would cause me concern, so proceed carefully.

But sounds like you have a few problems. Engine and gearbox should be earthed to the chassis. along with many other smaller 1s

J

dogdog1 · Oct 27, 2023

marjon said:
Anywhere on the chassis is good as long as its clean.
But sounds like you should connect it to the transferbox .

What makes you think this? This would cause me concern, so proceed carefully.

But sounds like you have a few problems. Engine and gearbox should be earthed to the chassis. along with many other smaller 1s

J

Thanks for reply . Wondering where the cable should end and not knowing any better I pushed the end of it against the side of the gearbox then connected the negative pole on the battery . Sparks and smoke made me lift it off quickly ! It was the last thing I had to do after replacing the gearbox . When I connect the negative pole with the cable the relays rattle but that's about it . A test lamp connected between the chassis rail and the gearbox lights up even with all earth leads and the battery negative disconnected !

tottot · Oct 27, 2023

Standard is battery earth to a bolt on the transfer box.
Seems like you have a major issue with the live feed from the battery going straight to your engine/gearbox.

dogdog1 · Oct 27, 2023

tottot said:
Standard is battery earth to a bolt on the transfer box.
Seems like you have a major issue with the live feed from the battery going straight to your engine/gearbox.

It was fine before I removed the battery cables and all the other stuff to change the gearbox . What did I do ?

marjon · Oct 27, 2023

dogdog1 said:
It was fine before I removed the battery cables and all the other stuff to change the gearbox . What did I do ?

Have you connected the starter lead wrong?

J

dogdog1 · Oct 27, 2023

marjon said:
Have you connected the starter lead wrong?

J

I had a guy looking at it today and he thought it was connected right . Anyway the problem persists even with the starter wires off and the wires to the difflock and reverse light switch and gearbox earth wires disconnected . All that's needed for the gearbox to light up is the positive terminal to be on the battery !

tottot · Oct 28, 2023

Pinched a cable somewhere when replacing gearbox, I did this a few years ago when refitting my heater box, smoke [ its what all electricity works on

] was soon escaping

Anaconda · Oct 28, 2023

I would also suggest you have trapped a cable somewhere.
With regards to earth cables you can never have too many.
If I remembered correctly the Series2a earth went from battery to engine block and front panel, also starter motor mount bolt to chassis. Once your live is sorted just add a couple of decent earth straps from chassis to gearbox and engine, can't hurt.

marjon · Oct 28, 2023

Cant be that many wires to possibly trap, and surely would be easy to see.

Alternator?

J

dogdog1 · Oct 28, 2023

All changed overnight , of its own accord . The gearbox is no longer live . The relays no longer rattle when I touch the battery negative cable to the pole . No dash lights come on . No ignition . No clue what's happening . Battery is fully charged .

marjon · Oct 28, 2023

dogdog1 said:
I had a guy looking at it today and he thought it was connected right . Anyway the problem persists even with the starter wires off and the wires to the difflock and reverse light switch and gearbox earth wires disconnected . All that's needed for the gearbox to light up is the positive terminal to be on the battery !

dogdog1 said:
All changed overnight , of its own accord . The gearbox is no longer live . The relays no longer rattle when I touch the battery negative cable to the pole . No dash lights come on . No ignition . No clue what's happening . Battery is fully charged .

So what are we dealing with here.
positive issue or earth issue?
cos I am now lost, that sort of stuff doesn’t fix itself.

Guess you have fried all the fuses.

J

tottot · Oct 28, 2023

Probably a cable melted through and disconnected itself or as above fuse blown. Lucky not to have had a full burn out. Got any service that is not now working?

dogdog1 · Oct 28, 2023

marjon said:
So what are we dealing with here.
positive issue or earth issue?
cos I am now lost, that sort of stuff doesn’t fix itself.

Guess you have fried all the fuses.

J

I have absolutely no idea what it is . All I know is I have a negative cable end that doesn't seem to be in reach of anything All fuses are good , including the big ones in the engine bay .

dogdog1 · Oct 28, 2023

tottot said:
Probably a cable melted through and disconnected itself or as above fuse blown. Lucky not to have had a full burn out. Got any service that is not now working?

Nothing is working . No chance of a burnout as I only jammed the cable end against the gearbox and then held the cable on the battery pole .

Anaconda · Oct 28, 2023

On my TD5 the earth cable goes through the battery box, connects to a long bolt going through chassis rail and then onto a gearbox or transfer box bolt, can't remember which.
300tdi probably similar.

tottot · Oct 29, 2023

For the gearbox to have gone live something had to be feeding it.

Anaconda · Oct 29, 2023

You can see the main battery earth cable going to the transfer box and an earth strap then going to the chassis. You need something similar to earth the chassis and the gearbox,engine etc.
Of course you can add anther elsewhere for chassis to engine, needs to be of similar size.

Anaconda · Oct 29, 2023

dogdog1 said:
Thanks for reply . Wondering where the cable should end and not knowing any better I pushed the end of it against the side of the gearbox then connected the negative pole on the battery . Sparks and smoke made me lift it off quickly ! It was the last thing I had to do after replacing the gearbox . When I connect the negative pole with the cable the relays rattle but that's about it . A test lamp connected between the chassis rail and the gearbox lights up even with all earth leads and the battery negative disconnected !

I am no expert on electricity, far from it, something I struggle to get my head round but you need a make a circuit for it to work. If the battery is not fully connected (no earth cable attached to it) how are you making a circuit between gearbox and chassis?

dogdog1 · Oct 29, 2023

tottot said:
Probably a cable melted through and disconnected itself or as above fuse blown. Lucky not to have had a full burn out. Got any service that is not now working?

Nothing is working . No chance of a burnout as I only jammed the cable end against the gearbox and then held the cable on the battery pole

tottot said:
For the gearbox to have gone live something had to be feeding it.

Anaconda said:
I am no expert on electricity, far from it, something I struggle to get my head round but you need a make a circuit for it to work. If the battery is not fully connected (no earth cable attached to it) how are you making a circuit between gearbox and chassis?

When I initially tried to make a connection between the chassis and the gearbox , sparks and smoke made me take it away double quick . After it changed its behaviour ( seriously ! ) I then connected the loose end of the cable to the gearbox with a jump lead , no problem . The only wires on my starter motor are the white one with the spade connecter , the brown one and the heavy black one , both of those on the solenoid . Is that correct ?

Where Does The Battery Negative Cable on a Defender Hi 300tdi Attach Beneath The Vehicle ?

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