RGS Fuel sender - circuit conundrum

[Sir Sidney Ruffdiamond]

Gauge showing nothing when all connected up !  but if i disconnect the harness from the sensor the following 

I have twelve volts from the two red wires coming from the clocks - individualing earthing them brings the fuel light on and the second the needle goes to full

If i check the continuity between the two spade connectors on the sensor i get a resistance 

The third wire is earth if i disconnect it and check continuity with earth on the wire its fine

The post it connects to on the base of the sensor shows nothing

How does the circuit work - does the sensor internally earth the two live circuits to the post with the green wire and create a a level and at the bottom excite the light  ? 

Any theories or just a *ucked sensor 

   

 

[MVma]

It was sent by John Wilson I believe:

RGS and RGS Corsa Electronic Fuel Guage Service Information.
Tested On an RGS Corsa by courtesy of Mr Neil Trillo. 2000

Panel guage calibration marks
1 = 10 ohms
3/4 = 51 ohms
1/2 = 98 ohms
1/4 = 144 ohms
0 = 240 ohms

pointer at rest ( minimum deflection ) = 540 ohms

Test procedure
If you borrow a resistance decade box and connect it to the Dark Green
wire and the Red/Black wire this will drive the panel gauge
(disconnected from the sender of course ) ignition on.

The yellow light is driven by the Red wire and if connected to the Dark
Green wire it will light, i have set this to come on at O on the fuel
guage, it is adjustable on the sender unit, email me if you want to
know how.... iismail@igreen.net

Sender unit will drive the guage on this Corsa with the following data;

pointer at rest on bottom stop = 2.4 Litres in the tank

0 = 3.6L

1/4 = 7.7L

1/2 = 10.7L

ran out of time to finish the calibration.....

actual sender unit Resistance when arm is in the following position

Lower stop = 340 ohms

Mid position = 96 ohms

Upper stop = 12 ohms
Mechanical Fault, check the rivits holding the sender unit inside the tank for loosness as this is the return path for the sender signal and needs to be secure for a stable reading on the road.

 

[drikko]

Here's a bad scan of the wiring diagram if it helps.

 

[Laverda SF]

Really: You got fuel level indicator in your Breganzie.

It's probably a Boche or Lucus Circuit where the a BROWN wire is ground and the Tank has to be grounded to frame and to the Negative post of the Battery.

I've had fuel tanks blow up for far less.

Just my my shit!

 

[sfcpiet]

If all else fails, NOS units are available from OCT.

piet

 

[Sir Sidney Ruffdiamond]

Just trying to exhaust all avenues before i stop , take the tank off- get a new sender - means not on the road  and if i tanl the tank off  i should replace the fairing mount with a sexy bearing made by Smiddy  - cheers Smiddy by the way