Wiring on 110 Defender Fuel Sender Unit

Hi. Ive just had my fuel tank replaced, and am having trouble with my
fuel gauge sender unit. It was working fine before it was taken out and
put back in again, but now I think the mechanic messed with the wiring
in a bad way.

There is a green wire (with round plastic end piece), and a yellow wire
(with a round plastic end piece) and then another wire which has the
usual flat plastic connector on it. The two main wires plug into the
unit okay though Im not sure in which order they should be ? But the
other third wire is just hanging loose as there doesnt seem to be a
connector on the sender unit for it ?

There is a round metal type protrusion from the sender unit in between
the other two connections, but the spare wire I have doesnt fit it
because its a square connector. Is it the earth perhaps ? Is it
supposed to have a connector on the wire which slides over the round
protrusion ?

Im really lost and quite annoyed because it was working fine before the
mechanic messed with it. When the wires were in one configuration the
fuel tank was always full (when half full), then in the other
configuration its always sitting just above the red even though it
should probably be IN the red. Quite confusing.

Anyway, Im hoping someone knows what Im talking about and can offer
some advice.

Thanks very much.

In message <[email protected]>
[email protected] wrote:

> Hi. Ive just had my fuel tank replaced, and am having trouble with my
> fuel gauge sender unit. It was working fine before it was taken out and
> put back in again, but now I think the mechanic messed with the wiring
> in a bad way.
>
> There is a green wire (with round plastic end piece), and a yellow wire
> (with a round plastic end piece) and then another wire which has the
> usual flat plastic connector on it. The two main wires plug into the
> unit okay though Im not sure in which order they should be ? But the
> other third wire is just hanging loose as there doesnt seem to be a
> connector on the sender unit for it ?
>
> There is a round metal type protrusion from the sender unit in between
> the other two connections, but the spare wire I have doesnt fit it
> because its a square connector. Is it the earth perhaps ? Is it
> supposed to have a connector on the wire which slides over the round
> protrusion ?
>
> Im really lost and quite annoyed because it was working fine before the
> mechanic messed with it. When the wires were in one configuration the
> fuel tank was always full (when half full), then in the other
> configuration its always sitting just above the red even though it
> should probably be IN the red. Quite confusing.
>
> Anyway, Im hoping someone knows what Im talking about and can offer
> some advice.
>
> Thanks very much.
>

Is it diesel or petrol, and age!

Richard

--
www.beamends-lrspares.co.uk [email protected]
RISC-OS - Where have all the good guys gone?
Lib Dems - Townies keeping comedy alive

> Is it diesel or petrol, and age!

Oh, sorry. Its diesel and its a 1990 110 County.

Thanks

Generally there are two wires leading to the sender unit - one is for the
low-fuel light and one is for the guage.

With the ignition on - earth each of them in turn - one will light the low
fuel light up and the other will send the guage to absolutely full if both
wires are working through to the dashboard. If both light and guage work,
then the problem is in the sender unit which is in the tank - they are cheap
to replace, about £20 or so.

If one wire does not work, but other does, then suspect the guage, light, or
wiring to be faulty. Find the same coloured wire behind the fuel guage as
is on the sender end - disconnect it, and use a multimeter to test
continuity - if it fails that, then the wire is broken somewhere. As a
double test of the guage, earth the terminal you just took the wire off -
guage should go right up.

If you find a wire is broken somewhere - its often easier to run a new piece
than find the break because the wires do run inside the chassis (done any
welding lately which could have caused the problem?)




--
Regards


David J. Button
<[email protected]> wrote in message
news:[email protected]...
>> Is it diesel or petrol, and age!
>
> Oh, sorry. Its diesel and its a 1990 110 County.
>
> Thanks
>

<[email protected]> wrote in message
news:[email protected]...
> Hi. Ive just had my fuel tank replaced, and am having trouble with my
> fuel gauge sender unit. It was working fine before it was taken out and
> put back in again, but now I think the mechanic messed with the wiring
> in a bad way.
>
> There is a green wire (with round plastic end piece), and a yellow wire
> (with a round plastic end piece) and then another wire which has the
> usual flat plastic connector on it. The two main wires plug into the
> unit okay though Im not sure in which order they should be ? But the
> other third wire is just hanging loose as there doesnt seem to be a
> connector on the sender unit for it ?
>
> There is a round metal type protrusion from the sender unit in between
> the other two connections, but the spare wire I have doesnt fit it
> because its a square connector. Is it the earth perhaps ? Is it
> supposed to have a connector on the wire which slides over the round
> protrusion ?
>
> Im really lost and quite annoyed because it was working fine before the
> mechanic messed with it. When the wires were in one configuration the
> fuel tank was always full (when half full), then in the other
> configuration its always sitting just above the red even though it
> should probably be IN the red. Quite confusing.
>
> Anyway, Im hoping someone knows what Im talking about and can offer
> some advice.
>
> Thanks very much.
>

I think you'll find that the green wire you mention will be mostly green
with a thin black line on it as well, if so this will be the fuel gauge wire
and the other (yellow?) will be the low fuel warning lamp. The small spade
connector will be black and needs connecting to earth the unit as the
current passing from the gauge is very small and a bad earth can play havoc
with the readings. There is a small flat tag spot welded to the tank unit to
connect this earth wire and if it has dropped off due to corrosion you will
have to replace it or connect to the tank somewhere else, possibly by
extending the wire.

Martin