Econometer and Fuel Gauge

[Pretendent]

Hello. I have a little problem with my gauges.
firstly as i switch ignition on sometimes fuel gauge does nothing, and sometimes it moves to min position. as i noticed fuel gauge kind a working but it don't show engine temp cuz i drove 200km and its still in min position.
and the econometer, as soon as i start engine it goes off to full max, and when i drive a straight road with the same speed it drops a bit but still showing almost 30l/km.
any ideas any questions ?
any help?

[Brianmoooore]

The front half of the instrument cluster case houses a circuit board, known as the SI (service interval) board, but contains 90% of the electronics for the whole cluster.
There are two versions of this circuit board in use (impossible to tell which without opening the cluster), both have two batteries on them, but one has AA sized NiCd batteries, while the other has much shorter lithium batteries.
The NiCd batteries start to fail after eight years or so, and cause increasing problems as they do so. Eventually, they will leak corrosive liquids, which will render the board useless.
The first thing you need to do is inspect your SI board, and check the type and condition of the batteries. They may or may not be the cause of all or some of your problems, but this possible cause needs to be eliminated first.

[Pretendent]

Thanks for the reply.
I have suspicion on batteries too, I have measured them and they have 2.8 v on no load.
It have 2 short lithium batteries witch kind a soldered?? to the contacts, and glued to each other.Any idea how to remove them? cuz I haven't remove it yet while i don't have the new one. I I will try to search those batteries and try to replace them this weekend, will see what happens.
Ty for help and sorry for my broken eng

[Brianmoooore]

If you have the version of the board that has lithium batteries, then we may be on the wrong track. These batteries shouldn't leak, and should last for ever, as long as the instrument cluster is in a car fitted with a main battery. The lithium batteries are not rechargeable, are only used to power the boards memory when the main car battery is disconnected, and can do so for a couple of years in total.
Having said that, they are 3 volt batteries, so your measurement of 2.8 volts suggests they may be flat. The hot melt glue can be prised away, and then the batteries unsoldered from the board.
The batteries are available from CPC-Farnel, part number BT05108, but I don't know if they will deliver to Lithuania.

[Pretendent]

hello, this weekend i was on diagnostics and i find out that my lambda is faulty. could ekonomiser work wrong cuz of lambda ?

[Brianmoooore]

Economiser works of of two signals - the variable width pulses that control the petrol injectors from the engine ECU, and the road speed signal, processed by the speedometer and originating from the sensor on the back axle.
Can't see it being affected by the lambda sensor.