Wheres the power come from???

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
scott02464

scott02464

Active Member
Posts
710
Location
Up North!
This may be a simple question but im no electrician by no meens!

Im just about to wire up my Disco 200tdi engine in my 90!

It was a petrol V8 so (For me) was a bit of a mind fook for the wiring up bit.

Iv worked out which wire goes where and so on but its got me mind thinking!

Iv noticed that all the 'power' wires go from the + terminal on the battery to the starter and a wire goes from there to the Alternator!

In my head there isnt any wires going to the 'dash' / 'ignition key' / 'dash warning lights' (Apart from the 'choke' warning light for the glow plug)

So where do these get their power from??? I proberly have totaly missed the point here!

Also, the white wire in the loom..... is this wire 'swithed on' on the 2nd position on the ignition key?
And the white and red wire ' turned on' when the key is turned to the start position?

Any help would be much appreciated!

Scott
 
If you look at the smaller wires going from the starter main pos terminal you will note there are two going into the loom (well there should be), one goes to the alt, the other to the fuse box. They route everything via the main pos on the starter because it's as good as the positive terminal on the battery (when in good order) when it comes to charging via the alt, and when the engine is running the power ought to be coming from the alt anyway.
 
Last edited:
Thanks for that discomania! You dont happen to know the colouring of the little sed fuse wire do you?

Also, the white wire in the loom..... is this wire 'swithed on' on the 2nd position on the ignition key?
And the white and red wire ' turned on' when the key is turned to the start position?
 
The white and red wire down at the starter? Will come on in the start position which is 3 I think.

The solid white wire will be - ign switched - where have you found this one? Down at the starter loom?
 
No mate iv not found the white wire as such, im just going the use the old wire that went to the igniton coil (When it was a V8) which i believe is connected to the white wire......

this would come on when the igmition is at position 2 and will be connected to the fuel pump selonid for the fuel shut off.
 
nooooooooooooooo!
yu must connect the exciter wire to the warning lamp on the dash. Do not connect it directly to 12Volts.

Also do not try running your tacho from the doozil alternator - it will not work!
 
The Mad Hat Man said:
nooooooooooooooo!
yu must connect the exciter wire to the warning lamp on the dash. Do not connect it directly to 12Volts.

Also do not try running your tacho from the doozil alternator - it will not work!
Click to expand...

Whats an 'exciter wire' (Remember i dont know any technical wiring stuff!)

Also i dont have a tacho its the mechanical sort from the speedo cable....
 
reet - all alternators have a power out wire (or wires) and need to to have another (thinner) wire to get the alternator to start producing current - this is called the "exciter" wire and is the wire that goes from the battery (+) to the ignition switch, through the "battery warning" light and to the alternator. Without this wire, the alternator wont work. You need to have the bulb in the circuit, to limit the current anorl.

if yu aint got a tacho, then that bit dont matter.
 
Is the exciter wire labled on the alternator as 'D+" or somthing to that effect?

When i took the V8 out im pretty sure that i didnt have any wires going straight from the batt + to the ignition thats why its confusing me a bit.

When you say 'ignition switch' is that classed as the actual barrel which you put your key into?

Appologises for the lack of knowledge
 
scott02464 said:
Is the exciter wire labled on the alternator as 'D+" or somthing to that effect?

When i took the V8 out im pretty sure that i didnt have any wires going straight from the batt + to the ignition thats why its confusing me a bit.

When you say 'ignition switch' is that classed as the actual barrel which you put your key into?

Appologises for the lack of knowledge
Click to expand...

yu always have wires going from batt to ign (via fuse box tho). yes ignition switch = barrel.
I am amazed if yu dont have a "batt warning" lamp.
 
Yes i deffo do have a batt warning lamp however there were deffo no wires going from the batt to the fuse box.

I had one thick cable that went from the batt + to the sarter.

Does it go from the starter back to the fusebox?

Do you know what the colour wire is that would supply the fusebox to the ignition switch with power?

What is the D+ connection on the alternator? Is that where the sed excitor wire goes?
 
Last edited:
His is an old one like mine where the fuses are after the switches, and the power splits from the ignition switch to the other switches and then back to the fuse box for each circuit on its way to the lamps etc.
 
Just an up date from all my previous questions!


White wire in loom = 'Turns on' on position 2 on the ignition swith.
White and red wire in loom = 'turns on' when the key is turned to the start position.
D+ = wire that comes from the alternator to the dash warning light.

On mine the power to the dash/ignition switch comes from a power cable attatched to the alternator (Where the batt+ wire is connected) And goes from there into the where that loom comes out of the bulkhead on the engine bay side.
I dont have any wires going to my fuse box directly from the batt.

All wired up today no messin! Dont know what all the fuss was about :cool:

Scott
 
You must log in or register to reply here.

Similar threads

cappers
Shorted the ignition switch feed!
Replies
7
Views
603
miktdish
miktdish
S
Glow plug power
Replies
10
Views
1K
Singr07
S
J
Help please! Electrical issue with 1995 Defender 110 County, 300 tdi
2
Replies
35
Views
2K
Oliverryan96
O
A
Fuel gauge and fuel light issue
Replies
9
Views
649
Acdadefender1
A
D
Loss of power on td5 06 plate but comes back again while driving
Replies
6
Views
549
Anaconda
A
Back
Top