are instrument guages controlled by software ?

[handsomejackuk]

I just wondering as this is my first bmw have had it almost a year now...

are temp and petrol guages controlled by the ecu, rather than proper old analogue values....?

i note that when my petrol reserve light comes on to reserve it does not extinguish when going around a corner or parked uphill for instance... and it indicates orange and the fuel guage goes right down to zero not a gradual decline to zero... to me this indicates that it must be software controlled and not an analogue guage...

i just wondering if the temperature guage works in a similar way.. i.e. not directly connected to the sensor but more lets say controlled by the ecus approximation of temperature...

is this a BMW thing ?

 

[littlefeller]

it is all controlled via the dme i think, apart from the mileage which is stored in errrm elsewhere, this is quite handy if you need to swap your clocks for any reason, but im not going to say HOW to do this on an open forum

if you look through the coding of your car it does look as though the temp and fuel can be adjusted in the coding, or rather the ecu interpretation of it.

the fuel tank as a sender unit, so it is feeding info back to the dme, my gauge doesn't go down gradually either, it kind of drops in stages, one minute it looks as though you have plenty of fuel, then you look again a few miles later and. if you sit in traffic (much easier to see now your thermostat is kaput) you can actually see it rising in steps.

i think the z3 and E36 is a kind of crossroad for this kind of thing, as its neither fully analog nor fully digital, kind of a mismatch of both, and how they have solved some of the problems this presents is sometimes a little odd.

 

[Nodzed]

and the fuel gauge goes right down to zero not a gradual decline to zero.

Welcome to my world

On a serious note my temp & fuel gauges starting showing incorrect values and rev counter stopped working all together on the red Zed, now for no apparent reason they are all working fine again I can only assume it was damp and they are totally electronic. guessing really though.

 

[handsomejackuk]

yeah it all seems a bit strange to me... being used to analogue stuff.....i suppose the more modern car have even more electronics on them...

 

[Ianmc]

yeah it all seems a bit strange to me... being used to analogue stuff.....i suppose the more modern car have even more electronics on them...

In my youth, it was generally rust that finished cars. In the future it will be electronic failures. Progress?

 

[Redline]

I just wondering as this is my first bmw have had it almost a year now...

are temp and petrol guages controlled by the ecu, rather than proper old analogue values....?

i note that when my petrol reserve light comes on to reserve it does not extinguish when going around a corner or parked uphill for instance... and it indicates orange and the fuel guage goes right down to zero not a gradual decline to zero... to me this indicates that it must be software controlled and not an analogue guage...

i just wondering if the temperature guage works in a similar way.. i.e. not directly connected to the sensor but more lets say controlled by the ecus approximation of temperature...

is this a BMW thing ?

It could be the fuel sender. I think as stated earlier, it is much more complicated than an old sender type. I think it has a pcb with some kind of array on it that is swept by a pick-up. If that goes faulty at any point (one of the contacts goes awol), the eco is likely to think that the gauge is at its lowest and consequently lights the low fuel light at the same time. The low level warning latches. That will only extinguish when the sender gives a signal that indicates a higher level of fuel - just going around a corner or up/down hill may not be sufficient to trigger that change.

If your temperature gauge is also fluctuating then it could be an earth on the display harness, but, I'd suspect the sender in the first instance.

Many devices are like this nowadays. Had an amplifier that would, without warning, switch to max volume. At 200W per channel - That's entertainment with jeopardy!

 

[littlefeller]

It could be the fuel sender. I think as stated earlier, it is much more complicated than an old sender type. I think it has a pcb with some kind of array on it that is swept by a pick-up. If that goes faulty at any point (one of the contacts goes awol), the eco is likely to think that the gauge is at its lowest and consequently lights the low fuel light at the same time. The low level warning latches. That will only extinguish when the sender gives a signal that indicates a higher level of fuel - just going around a corner or up/down hill may not be sufficient to trigger that change.

If your temperature gauge is also fluctuating then it could be an earth on the display harness, but, I'd suspect the sender in the first instance.

Many devices are like this nowadays. Had an amplifier that would, without warning, switch to max volume. At 200W per channel - That's entertainment with jeopardy!

yes it has an array on it with the good old fashioned float, it goes by an average over a period of time, but yes if it just drops straight to zero then there must be an issue some where as mine steps down through the red zone and doesn't just drop to zero, good job really as mine spends most of its time in this part maybe yours was driven like it too and has worn that part out

 

[handsomejackuk]

i have had the dash out to replace some bulbs a few months ago suppose it wouldnt hurt to take the dash out again and make sure all the connectors are pushed nice and snuggy....