Troll Hunter Posted July 9, 2016 Share Posted July 9, 2016 Having been motoring for many ks of km relying on the odometer for refueling intervals I've just fitted new sender and gauge. Result: not working! Both came in blue boxes. The gauge appears to work correctly, indicating "full" when one side is 12v+ and the other side is earthed. My vehicle was originally fitted with a 3.5 V8, so I've replaced the sender unit with the same as the original, STC1482. I don't think this should affect its functionality since it ran on diesel fuel for some 10 yrs before failure, after some 14 years on petrol. Investigating, with the sender unit back on the bench, it appears that the three little arms that make electrical contact with the slider only provide continuity when the float arm is in the "empty tank" position. As soon as the arm is moved towards "full", even a little bit, continuity is totally lost. I have separated the arm and cleaned the tracks and arm contacts, but no improvement. Question 1: The sender has three terminals. Am I correct to assume that the centre one is earth and the other two are gauge and "low level warning light"? Question 2: should the electrical resistance across the sender terminals, top to centre and bottom to centre, vary as the arm is moved from the "full" to "empty" position? Many thanks, in advance, for any help. Mike Quote Link to comment Share on other sites More sharing options...
western Posted July 10, 2016 Share Posted July 10, 2016 I believe you will find the information required in this post Which wires where on fuel tank sender unit??? Started by Troll Hunter, Nov 01 2012 03:46 AM Question 1: The sender has three terminals. Am I correct to assume that the centre one is earth and the other two are gauge and "low level warning light"? Question 2: should the electrical resistance across the sender terminals, top to centre and bottom to centre, vary as the arm is moved from the "full" to "empty" position? Q1 answer see above link Q2 answer = I don't know what the resistance reading should be, but AFAIK it's a variable resistor so there should be some resistance across the windings to make the gauge move to show fuel contents. Quote Link to comment Share on other sites More sharing options...
stephencdavies Posted July 10, 2016 Share Posted July 10, 2016 I had this problem. easily solve by buying a new bearmark sender. they are quite cheap to buy and easy to fit. as you've already removed your sender why not just pop a new one in. i've had many problems over the last few months with parts in blue and white boxes. the extra few pounds spent on OEM / Bearmark will save you grief. Quote Link to comment Share on other sites More sharing options...
Peaklander Posted July 10, 2016 Share Posted July 10, 2016 The sender needs 12 volts across the full resistance and the wiper contact (which is moved by the float arm) moves between one end of this resistance and the other, picking up from 12V at one end to 0 volts at the other. So if you have an ohm meter and with things disconnected from 12v, find the two contacts with the greatest resistance between them (with the float somewhere in the middle of the travel). Those are the two that need the +12v and the 0v (ground / earth). The third contact is the wiper and the gauge is connected to this. It will pick up from 12v at one end of the wiper travel, to 0v at the other (to show full to empty). If you connect a meter and measure the resistance from the wiper contact on one side to each of the other two connections in turn, the resistance will move from close or equal to zero ohms when the wiper is at one end of the travel to maximum ohms - actually the same as between the two main contacts that you found before, at the other end of the travel. If the wiper loses its connection as the float moves through the range of travel then it is indeed faulty. Quote Link to comment Share on other sites More sharing options...
montyjn Posted July 11, 2016 Share Posted July 11, 2016 From memory the only options for STC1482 are LR or Britpart; don't think Bearmach make one. Quote Link to comment Share on other sites More sharing options...
stephencdavies Posted July 11, 2016 Share Posted July 11, 2016 stc1139 for defender 90 and amr 1495 for the 110 both are Bearmach. thats according to a well known auction site. ( L R Parts ) i've recently fitted the one for my 90, it comes in a green branded Bearmark box, as does the one for the 110 / 130 which i fitted for a mate. Quote Link to comment Share on other sites More sharing options...
montyjn Posted July 11, 2016 Share Posted July 11, 2016 Ok. So is the only difference between them that one has a plastic float and the other a metal one? I assume STC1482 is metal (petrol) and AMR1495 is plastic (diesel)? Otherwise, from what I can see they both are wired for the low fuel warning light.. Does anyone have any experience of using the ARM1495 (i.e. plastic float) in a 110 petrol v8 (apologies for taking this a little off-topic)? Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted July 11, 2016 Author Share Posted July 11, 2016 Thanks for reminding me of my own post, Western . Old age doesn't come alone, but I can't remember what it does come with ! But the good thing about asking this question again is that I've now got additional info. Yes, it does look as if I've got a regular blue box component - from new, it doesn't work, so back to ordering an OEM unit, and continuing to use my odometer to calculate refueling needs. Many thanks to all who have responded to this post. Mike 1 Quote Link to comment Share on other sites More sharing options...
western Posted July 11, 2016 Share Posted July 11, 2016 Your welcome, I have a spare new unfitted sender for a 110 here if you can't source a new one easily, my spare is a Allmakes part, Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted July 12, 2016 Author Share Posted July 12, 2016 Hi, Western, Many thanks for your kind offer. PM sent. Mike 1 Quote Link to comment Share on other sites More sharing options...
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