Urgent alternator help needed!!!

Right then im after some help with this damm thing

My alternator died, or so I though, so I brought a used one. Fitted it and still the same. Not getting no charge to the battery. I then brought a brand new one and still no charge. A multimeter to the battery is giving me 12.7v when running with no change when revved.

Is there anything else that is known to go wrong? Or does anybody have a wiring diagram so I can understand it a bit more?

The car in quesion is a 200tdi defender 90 and the alternator just has 1 plug with 3 terminals.

Really starting to **** me off now and this is my only car for a while so need it done!!


Thanks in advance!!!

it needs the bulb in the dash to work in order to excite the alt. iirc it is the thin brown and yellow stripe.

if you unplug it and earth that wire, your bulb should come on your dash (ign on)

if not go trace the wire back looking for issues/ check the bulb/ check the fuse.

As far as I know the bulb in the dash has never worked. Ive owed it for many years and killed a few alternators but never seen the light on??

And another question. I have a plug on the back with 3 terminals. What does each one do? Does it require them all to get a charge or are the other two just for indication purposes?

12.7 volts that alternator is fecked to you should get 14.2 to 14.8 at the battery when charging

biketeacherdave said:

12.7 volts that alternator is fecked to you should get 14.2 to 14.8 at the battery when charging

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I know what I should be getting. My point is 3 alternators are giving the same result so the alternator itself clearly not the problem

check the wiring.

I know but I dont know what to check. Where should the 3 wires be going to and whats required to start?

My undersatanding is this:
Main wire straight to batterry(maybe passing through starter)
Other bigger terminal gos through a switched live(ignition), fuse, then back to the smaller terminal?

Does this sound correct???

I suggest you do a :googleit: search. I have posted the info many times. There is even a complete thread on testing alternators.

i've told you what's wrong and what to do. now go fix it

Two heavy wires go from alt to starter then on into system
Thin brown wire with yellow trace is battery tell tale lamp
Check these wires and test for resistance
Get that bulb in dash sorted swap it with another there's usually extra unused in the warning lamp cluster and check the fuse
It ain't hard just trace the relevant coloured wires and you'll find em
Hang on .....,, do what trax sed lol

I'll be back on it as soon as I finish work. Thanks.

Right then unitill I get time to start tracing the wireing I bodged it! I just put a link direct from the smallest wire on the alternator direct to the permanent live and it works. I have a battery isolation switch I can turn off when not using so I dont get a drain.

Thanks for the advice.

ricky31290 said:

Right then unitill I get time to start tracing the wireing I bodged it! I just put a link direct from the smallest wire on the alternator direct to the permanent live and it works. I have a battery isolation switch I can turn off when not using so I dont get a drain.

Thanks for the advice.

Click to expand...

that wasn't the advice and it shouldn't have 12v going to it.. but since you don't listen and are a bodger.. enjoy!

ricky31290 said:

Right then unitill I get time to start tracing the wireing I bodged it! I just put a link direct from the smallest wire on the alternator direct to the permanent live and it works. I have a battery isolation switch I can turn off when not using so I dont get a drain.

Thanks for the advice.

Click to expand...

NOOOOOOOOO! yu will destroy the Alternator - but good luck. Yu got a fire extinguisher?

Oh for ####s sake

Sniff sniff hmm electrical fire anyone?

Sniff sniff electrical fire anyone?

The wiring diagram states it gos through the ignition, through a fuse the back to the other terminal. What difference does it make if i just cut out the above out??

the light?