ABS light coming on when tank half empty

[ALBERT10]

2005 S80 D5 2.4 turbo auto

Seller is saying if the fuel gauge drops below half full the abs warning lamp comes on and the trip computer goes off and the heated seats stop working. But if keep tank above half full everything works fine.

Any idea what this could be? Sounds a very peculiar fault. Why would fuel level trigger that? Any ideas or anybody heard of this before?

[Spike56]

Trapped wires beneath the tank? Or near the suspension or wires being stretched or released by the weight changes?

[ALBERT10]

Originally Posted by Spike56

Trapped wires beneath the tank? Or near the suspension or wires being stretched or released by the weight changes?

Yes that sounds a possibility. Has anybody heard of anything like this happening before?

[Wagon Sailor]

I'm not convinced the tank itself moves sufficiently to trap wires. In any case, the problem occurs when the tank's contents lighten.
Could there be a short somewhere else that passes on a voltage change when the fuel level sender reaches a certain point?

[ALBERT10]

Originally Posted by Wagon Sailor

I'm not convinced the tank itself moves sufficiently to trap wires. In any case, the problem occurs when the tank's contents lighten.
Could there be a short somewhere else that passes on a voltage change when the fuel level sender reaches a certain point?

But why would it be passing on a voltage change at the half way point, it’s just a gauge level? And how would the heated seats be effected , can’t imagine they are on the same circuit as anything to do with ABS or fuel level?

Thing with faults like this is wont fix itself and with ABS light may end up permanently on. Then car is junk for MOT purposes till it’s fixed.

[stuart bowes]

I don't pretend to be aware of how it all works but it does occur to me that the fuel gauge is part of the DIM which is known to be problematic

But then the failure symptoms are perhaps controlled by or at least passed though the CEM which is also a known weak point

I would probably start by emailing Tilbury volvo diagnostics and asking them if they think there's any way a relay or dry joint etc could cause these issues. Seeing as an email is free and takes all of 5 minutes

That is unless someone else comes along with a better idea

Is it possible the cause and effects are not actually linked or do you fully trust the info to be logical and throughly tested

There are some under seat connectors which could be more likely, would a yaw sensor for example if fitted affect abs when it fails (?) And obviously the seat heater connector would be in a similar place. But how that would relate to fuel level I don't know. Possibly just all coincidental and nothing to do with it

None of this is based on 1st hand knowledge