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MG TD TF 1500 - Fuel warning light

I'm a relatively new (July 05) TD owner and learning. My fuel warning light seems to work backwards (i.e. the light is on most of the time and goes out when fuel is low. Does this make sense to anyone?
R. J. Lowery

The way the screw pattern is designed for the fuel tank sending unit on your tank, I belive its possible to intstall the unit upside down, which would explain your problem. The electrical terminal on the sending unit should be on top. If yours is on bottom then its upside down. The little cover plate on the sending unit is marked 'TOP', has an offset screw pattern, and will only go on one way. The unit itself, however, has a symmetrical screw pattern and can be installed upside down if the installer didn't notice the 'TOP' marking on the cover plate.

My problem is that my green light is always on, so I've got it off right now seeing what the problem is. The float appears to be good, so I'm not sure yet what is up.

B Sieling

Bob, you might want to take a look at to get an idea about the circuit.
Bud Krueger

Bryan - Does your light stay on even with the wire disconnected from the terminal on the sending unit? If so, the problem is a short to ground in the wire from the sending unit to the light. If the light only stays on as long as the wire is connected to the sending unit, it is quite possible that the insulation material around the terminal on the sending unit has deteriorated and allowing the terminal to touch the edge of the case. Good luck - Dave
David DuBois

Good questions. I've got the sending unit off right now and disconnected (obviously), so I'll check tonight when I get home to see if the light still comes on with the key.

Regarding the insulation material around the terminal, how does one check for that and replace if needed?

I did order a new gasket set from Abingdon and got three gaskets, one of which is a small round one for the terminal. Where exactly does this terminal gasket go? Does it serve as the insulation you are talking about or is that something else entirely?

Thanks much
B Sieling

When I installed the sending unit it the tank, the tank was on my bench and I didn't notice the orientation so I installed the unit upside down and had the same problem. The black knob should be on top of the installed unit. I emptied the tank, reversed the unit and it worked fine. Have a good day!

John Progess

You have a black knob? Cool! I just have a small brass nut on my terminal.
B Sieling

Your fuel warning light was wired for South America.
It will work right once you drive past the Equator.

Hasta La Vista!

M.E. Blackwelder

Bryam - The small round piece of tubing should slide down the terminal and into the housing toisolate the terminal from the housing. Further, as I remember (and it's been nearly 25 years since I fussed with the thing) there should be a piece of insulating paper (known in the electrical world as fish paper) both inside and outside the housing so that no part of the terminal or the nut on the outside touches the housing. While you have the sending unit off, use a multimeter set for resistance to see if the terminal is connected to ground with the float held all the way at the top. If it does, you have found your problem and it is most likely one of those insulatting pieces around the termainal.

Incidentally, the blcak knob is available from Abingdon Spares. Look at the page with the fuel pump as it is used on those also. Good luck - Dave
David DuBois

Blcak knob = black knob to those who don't type faster than they spell ;) Dave
David DuBois

Reactivated thread. I've found it difficult to locate every thread on this subject & just came across this one. I believe I can effectively seal the cover & the base of the unit but I'm still not clear on the terminal replacement, the sequence of the various washers, nuts, insulating material, fish paper, signal wire & Bakelite knurled nut, (none of which I have). Patent No 447499 seems to have a number of versions of electrical pickup. The attached pic from George shows the internal base of the brass terminal, which is the same as my sheared off post, but I can't find an image of the terminal & it's various fittings. Anybody successfully replaced a terminal & able to shed some light? Cheers
Peter TD 5801

P Hehir

This one from Bud Krueger is the only other image I could find. It shows the knob but not much else. Cheers
Peter TD 5801

P Hehir

Think I found it. This is a view looking down into the terminal. There appears to be a brass nut on the screw, above a washer. I'll check my 'the53' files for more. Bud

Bud Krueger

BTW, the A/S gasket set includes a washer of the type that's under the nut. Bud
Bud Krueger

This thread was discussed between 07/11/2005 and 19/07/2015

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