The gauge is my TL has gone the way all of them go...dead. Mits want $160.10 for a new sender and that's with the $A as high as it is! After doing a search on this forum I found that a few comments made were that the actual sender unit appeared OK but the wiper unit was "dead".
Now I always figured that when they failed it was due to one or more of the segments that the wiper arm slides over was broken, but apparently this may not necessarily be so.
Another search on Google resulted is a site where this Yank has this same problem and solves it by cleaning the unit with vinegar/salt solution to remove whatever has been built up on the wiper.
So I'm going to go the same way but use CRC contact cleaner or similar.
Question: has anyone actually tried repairing the unit and if so was it successful.
Thanks.

When I pulled mine out to replace it with a second hand unit it started to work again and didn't look worn out. Pulling it out and cleaning it will see it working again, but for how long who knows. If you do it yourself then it fails again it is only half an hour of your time wasted, worth the risk I reckon.

Thanks for the reply jimbo, I'll pull the sender unit soon as I get the fuel level down a bit and post some pics if it is successful. No way are Mitsu going to get $160.10 from me without a fight.

Tell mitsu to get stuffed. Blast the buggery out of it with CRC cleaner and give it a go. If all else fails get a second hand one from a wrecker

If you can get your hands on an ohm meter place it on two terminals and move the float arm up and down if it does not read the gauge wiring has open circuited there are 3 terminals from memory one is for the low fuel warning sender the other are one for the windings and earth . No ammount of spraying anything will fix it , the float arm rubs on the wiring and if you look carefully you will see the wear , you may have to bite the bullet . Cheers Tom

If you can get your hands on an ohm meter place it on two terminals and move the float arm up and down if it does not read the gauge wiring has open circuited there are 3 terminals from memory one is for the low fuel warning sender the other are one for the windings and earth . No ammount of spraying anything will fix it , the float arm rubs on the wiring and if you look carefully you will see the wear , you may have to bite the bullet . Cheers Tom

I've thought about that aspect as well - if that's the case then maybe I could lengthen or shorten the wipe arm so that it contacts a different position that is not worn. Maybe even modify the shape of the wipe arm contact area so it is broader and contact unworn areas. I've got a kit lying around somewhere for making printed circuit boards - maybe that will come in handy to re-plate the surface. I've got a VOM meter etc as that was part of my job.
I realise that all this will probably be a total waste of time but I like mucking around. Many thanks for the comments.

Im going on memory now , but look at the windings you will see i think at the top section when the arm is up the windings are very closely wound and as the arm goes down the windings become spaced apart this varies the resistance hence the display of the dash gauge the open circuit usually occurs where the windings are spaced together tightly . Unfortunately these windings have been spaced according to float arm position and cant be altered . you will also notice that the windings board actually pivots with the arm this is supposed to give longivety to a sender unit . The wire is crap quality this is what wears . Good luck lets know if you have any luck tinkering round . Cheers Tom .

Thanks Tom, I thought the board was a printed circuit type - if it's wire it may be nichrome resistive wire......I've got plenty of that in old variable pots/resistors to salvage if possible to replace. I'll post results whether success or failure.

It is a small printed circuit board. You can flip it out of the plastic holder. Mitsubishi should just sell the board, it would only cost a few dollars to make. Have you tried Bursons, they seem good for parts on Magnas.

Thanks Jimbo - I 'll pull it first and see what the go is. At least I'm a bit better informed now.

I know this is an old thread, but are these PCB's actually available?

I have 3 of these sender units for a 2nd gen and all are erratic at certain spots.
Meaning the resistance changes fine with movement but goes high (open circuit) on some spots.
Cleaning the tracks and the sliding contact has made no difference.
Its not that the tracks are worn away completely but obviously not making good contact with the glider at these spots.

I suspect that there may be some crud on the resistor, if it works some times and not at other parts of the range. The sender unit is a resistor with a wiper arm which contacts along the length of the resistor. If there is a break in the resistor, it will not work beyond the break, but operate OK up to that point. Try cleaning the resisto and wiper unit with contact cleaner.

With my wife TM magna, we used LPG most of the time, and the petrol level didn't change very much at all. Constant vibration eventually caused the wiper to wear through the resistor coils, and the gauge was U/S.

Yes, there are resistor elements plated onto the circuit board and each segment is connected to a thin PCB track.
The wiper arm slides over these tracks and you get a non linearly increasing resistance between the two contacts.

One of my cct board's clearly has 3 worn tracks at the mid point, however these are not worn all the way to the substrate.
Surprisingly the wiper loses contact at that point, even after bending the wiper arm to increase contact pressure.

Similarly the other two sender units go intermittent at certain spots, eventhough the tracks are fine.
I suspect these sender units would work mostly okay as the wiper arm moves around a bit in actual use.
Probably affects the pulse averaging at the receiver end (ie inaccurate reading!).

All in all it seems these sender units are very sensitive to wear.
The circuit board would be very cheap, if you could get it, and compared to replacing the whole item.

http://i.imgur.com/DICVcJu.jpg

Just as a comment:
All of my PCB's had a lot of black deposits between the tracks.
These deposits clearly are not conductive and are easily washed/brushed away using a strong alkaline based degreaser.
A cheap, 5 litre container, with a strong degreaser is available at bunnings (Kenco brand) - it has around 35 g/l alkaline salts, and is only $9.
I bought it for cleaning a fuel tank!
For reference, a small bottle of radiator flush has about 65 g/l of these alkaline salts.
Do WEAR PROTECTIVE GLASSES as you don't want this stuff in your eyes.

AQUAR: Looking at your photo, it is obvious that the wiper blade has worn through the tracks on the PC board. It is possible to displace the wiper blade sideways so that it runs on a different part of the track? It probably won't help, because I suspect that the tracks are all in series, and you would have to join up the breaks in the racks - maybe with solder. That should work, but not for the wiper to go over the solder (That wouldn't last very long at all).

erad:
The worn tracks are still fully conductive along its lenght and are only almost through to the substrate.
Actually they are not in series with each other but rather they provide a path between the resistor segments and the wiper arm.

That said, relocating the wiper arm contact to travel lower on these tracks (by bending) might work out if you can keep the
contact pad parallel to the CCTB.
I will experiment with this if I get another working sender unit for the KS (a nearly working sender is still better than a broken one!)
Have to be carefull as these parts are just too hard to come by for this KS model.

Just as an update:
The sender unit that came out of my own verada, remained quite intermittent even after cleaning all the crud off and "wiping" the wiper arm contact.
The were no obvious signs of worn tracks on this sender unit, unlike in the picture above which was for the sender unit from the wreckers.

In the end I polished the wiper arm contact with very fine wet and dry and found that is was still coated with Asphaltine/Varnish.
Surprised me but happy that this fully restored the functionality of the sender unit.

Its all back in now and working fine.

Just as an update:

In the end I polished the wiper arm contact with very fine wet and dry and found that is was still coated with Asphaltine/Varnish.
Surprised me but happy that this fully restored the functionality of the sender unit.

Its all back in now and working fine. Hi, so the original contacts are protected with this asphalting/varnish ? What did you do about the gasket? Did you buy a new one or used your old one? I have a wagon TJ that does not know when the bottom of the tank actually is and does not give the tripmeter correct information like how far i can travel on whats left in the tank.

The contact on the sliding arm is probably protected by a silver cadmium oxide plating.

The "varnish" substance comes from the additives in the petrol.
These can settle out and grow like crystal flakes that are very difficult to dissolve (ie the petrol has gone off!).
People with dual fuel systems often run into this problem as the petrol is not refreshed often enough.

My situation was that the whole fuel tank was contaminated with this Varnish and ditto the fuel sender unit and the wiper arm contact.
The contact looked clead but still needed wet and dry to polish away this Varnish.

By gasket you mean the rubber seal?
I re used this rubber seal as it was still quite pliable and is retained by lots of screws.