Series 2a fuel guage

[zulu Delta 534]

How can I test the gauge itself? If I run direct power to the back of the switch should the needle show full or what?
Has two tanks and the wiring doesn't show up on the manual so I am feeling my way.
Glen

[JDNSW]

I can't remember which way the gauge works, but remember that the sender and hence the switch is in the earth side of the circuit relative to the gauge.

If you have a multimeter, the moving contact of the switch should show voltage when the ignition is on. Depending on whether it is an early (up to suffix 'C') or late gauge this will be a steady voltage or an intermittent one. If no voltage at this point, look back towards the gauge for the fault, remembering this is in the only fused circuit on the 2a. If there is voltage at this point, check for voltage at each sender as the switch is operated. Note that problems are most likely to be earthing problems, once you have established voltage is getting to the gauge, for example earthing of the tanks. Although bad connections in the wiring may also be a problem.

Without a multimeter, the first check would be with a test light at the gauge - no voltage there (ignition on) check the fuse and its contacts. Then try running a wire direct from the gauge to one sender. If a test light shows voltage there, then check between the body of the sender and the engine block to show up a faulty earth.

Hope this helps.

John

[foz.in.oz]

Not sure about the model you have but some fuel sender guage circuits have a ballast resistor in them. This is to step down the voltage to give it the correct reading. sometimes these can fail, giving the wrong guage reading, ie tank is empty when guage shows half! If the guage is totally dead, then as stated before in previous post voltage missing or bad connection somewhere could be the cause, incorrect reading, resistor or poor connection. Also check the sender has a float on it! Sounds silly but they have been known to come off or leak becoming a sinker.

The ballast resistor is usually on the back of the binacle panel.

[JohnE]

Glenn i think there used to be a series 2a electrical schematic in the downloads section, but its not there any more the downloads that were up top of here ( thats an admin thing only the site god would be able to say why)

but i;ve had a look for you and it appears the gauge ( thats if you have a negative earth)is directly powered from the voltage stabiliser

starts like this,

power in from the fuse green wire( A3-A4) to the voltage stabiliser, it should sit behind the dash, then light green wire going from the stabiliser to the gauge usually the input is on the top lug of the back of the gauge, then the wire from the gauge to the sender.

I can do a photo if you like of my setup

A simple way of testing the sender, to the gauge , is to either get the sender out of the tank or use a spare one, ( remember the body of the sender needs to be earthed) power it all up and move the arm on the sender manually to replicate the fuel level in the tank. ( that checks both the sender and the gauge) ( but if you use a multimeter first as foz said and check the input voltage from the stabilser, should read 10 volts)

How do I know it works, because, on each item on the loom and ancillary devices on mine I have tested each one individually. I found the fuel guage was easy, it was hard to do the temp sender though.

anyway if you haven;t already got one, here is a good link for some schematics


Land Rover FAQ - Repair & Maintenance - Series - Electrical - Reference - Wiring Diagrams (http://www.lrfaq.org/Series/FAQ.S.elec.html)


forgot to mention the schematics on that page appear like leonardos writtings, if you left click the mouse a couple of times it magnifys and brings the details to a readable level


john


btw got a roast done on friday

[JDNSW]

Not sure about the model you have but some fuel sender guage circuits have a ballast resistor in them. This is to step down the voltage to give it the correct reading. sometimes these can fail, giving the wrong guage reading, ie tank is empty when guage shows half! If the guage is totally dead, then as stated before in previous post voltage missing or bad connection somewhere could be the cause, incorrect reading, resistor or poor connection. Also check the sender has a float on it! Sounds silly but they have been known to come off or leak becoming a sinker.

The ballast resistor is usually on the back of the binacle panel.

The "ballast resistor" is actually a 10v thermal voltage regulator. In the 2a it is mounted against the bulkhead behind the instruments. It must be earthed properly and will cause the gauge to overread if not. They occasionally become faulty, but many of the ones declared "faulty" by replacement only had a bad earth, fixed by the process of replacement.

However, these were only fitted from chassis suffix "D", and so should not be on yours, although after forty-five years heaven knows what it has!

Note that this voltage stabiliser gives intermittent output - i.e. the 10v is on average by having 12v switched off for about a fifth of the time.

I seem to remember that if the earlier gauge or sender is used with the later gauge or sender, the result will be a reversed reading - full when empty and vice versa. An easy way of telling which gauge you have is that if the gauge moves instantly when switched on it is the earlier one, if it takes about thirty seconds or more to move to the correct reading, it is the later one.

John

[zulu Delta 534]

The gauge is on Onslow (63 S2a) and resultantly is pretty archaic. (The fact that Onslow is a gunbuggy and once fitted with a 106mm rifle is a pretty good reason to be suspect of the gauge's innards!) No resistor that I can find, one side has one male spade connector, whilst the other side has two parallel male spade connectors.
As I read it the positive (earth) runs via the chassis to the tank to the sender unit, then to the two way switch (more mystery here) then to the gauge then to the fuse. (Or vice versa, depends on your outlook.)
This vehicle has S1 tanks on it so I can put my hand inside and move the float up and down so this eliminates float problems.
My biggest problem is working out why there are two prongs on one end (although according to the schematics the wipers take their power from this power source) and only one on the other. Both prongs are mounted via rivets to the back of the gauge itself and seem to be the one piece of metal with a cut through the centre. This doesn't look to be logical to me but that doesn't actually account for that much at my age.
http://i262.photobucket.com/albums/ii115/glenpats/DSCF3137Small.jpg
Regards
Glen

[JohnE]

had a look at the schematic for the ser 1 i think you have hit the nail on the head, it seems the second connector is for the wiper motor,

the two way switch would only change the input lead from either tank so thats not a drama

so with the ignition on the gauge should work, just jiggle the float up and down.


john

[JohnE]

https://www.aulro.com/afvb/images/imported/2009/02/589.jpg

[JohnE]

glenn
further our conversation , I had a fiddle with the blinker can i have and the third pin is to light up the indicator light,

ie when the blinkers are flashing, so does the indicator light, so the third and 4th wires you spoke about , one of them must go on the third pin on the flasher can in order for it to flash,( if that makes sense)


john

[zulu Delta 534]

My problem is now solved. Earthing was the culprit. I had checked the earth to the tank then to the sender units as I assumed (we all know what that means) that as I had had them all apart and painted and coated them then that was where the problem would be, but no, the switch wasn't earthing to the dash!
Thanks to all who offered assistance.
Regards
Glen

[JohnE]

that was too easy,
hmm didn;t that come up in conversation. Good one to remember!

john

[bobslandies]

The early type of fuel gauge is a "moving iron vane" meter. The later type is fitted with a voltage stabilized heated bimetal type sender and gauge.
The first type was used generally up till the mid-60s in English vehicles.
It is very responsive to fuel movement in the tank.

The later or moving coil system requires a voltage stabiliser (that's the little resistor canister). This type is the bimetallic heated system. Basically this type has a damped gauge and does not have the needle bouncing in the gauge.

They don't mix. You need the correct matching sender, gauge and stabiliser.

For a very good technical explanation of both types look here:

FRED'S LAND ROVER PROJECT (http://www.griffco.ca/interest/landrover/LRrepairs.htm)

There is some good information here also:

MGB Electrical Systems: Your Colour ... - Google Book Search (http://books.google.com/books?id=b55_ZAs7ljYC&pg=PA142&lpg=PA142&dq=moving+iron+fuel+gauge&source=web&ots=JN1LHjEf6v&sig=bBdLTOAgpAbvkXYpZEidHFVUB0Y&hl=en&ei=EKyaScj0HYKUsQOD0emBAQ&sa=X&oi=book_result&resnum=1&ct=result#PPA143,M1)

Bob