S2 Xantia HDI Fuel Guage

howiedean · Post by **howiedean** » 10 Oct 2010, 13:15

Hi,

I have been having some problems with the fuel guage. It originally displayed incorrect readings that were corrected with a technical tap on the dashboard, however mine has now failed completely including low level light (no fuel level and the low level light illuminates all the time).
I changed the in tank pump and sender a couple of days ago (previous in tank pump from GSF last 14 months) and this has made no difference.

1. Does anyone know the pinout of the instrument cluster for the fuel guage (the blue connector)?

2. Does the system work by a change of resistance as the float switch moves up and down and is the low level light a seperated feed or just a know level of resistance in the system?

Regards

Howie

rory_perrett · Post by **rory_perrett** » 10 Oct 2010, 14:32

IIRC when I changed my lift pump (again fuel gauge incorrect reading problem started before pump change and continued after) there are only 2 wires from the sender, therefore I assume the low fuel light is related to a resistance value.

However, since changing the pump (and sender) unit I have another problem which is that the gauge can suddenly read empty (if its not got its other problem at the time) and the fuel light comes on.

The first time it did this I had a panic as the gauge went from about 1/2 full to empty over about 15 mins of driving. My first reaction was that I must have a fuel leak.

I didn't and I have concluded that somehow the float is getting stuck against the side of the tank or something. As the fuel sloshes around I assume it drops further and further down and can't come back up again until it is low enough for the fuel light to come on. This has happened a few times. For the first few occurances I took the pump sender unit out but in the end I have found that a few thumps on the tank from underneath is enough to dislodge it and return things to normal - ie light off if sufficient fuel in the tank and the gauge giving random high readings most of the time.

citroenxm · Post by **citroenxm** » 10 Oct 2010, 17:29

Hi

Ill try and help you here ASWELL..

It WILL be the little motherboard INSIDE the instrument cluster! Trust me, Ive been here, as my other post told, you with a 1997 P reg car...

The owner gave up after fitting a known sender in the tank to find it behaving the same, then he gave up and left it with me. After much pinning out, the sender is NOT connected to the uage, but goes directly to this circuit board first, then to the guage, and after swapping it for another one all was sorted...

If you remove the speedo you will find a small circuit board... I cannot remember if its removable or not, but this will be your cause...

Paul

howiedean · Post by **howiedean** » 10 Oct 2010, 21:08

Thanks for the replies gents,

Howie

addo · Post by **addo** » 10 Oct 2010, 23:10

Yes, as Paul says this is an ongoing issue elsewhere. It appears a diode may go to dead short. Checking resistance to ground on both sender feeds, may help (use a good quality meter).

citroenxm · Post by **citroenxm** » 11 Oct 2010, 13:12

http://www.frenchcarforum.co.uk/forum/v ... hp?t=32719

Just thought you may like to read this posting...

As addo has mentioned...

Paul