Fuel tank guage.

[Shonkie]

Hello everyone.



I have today found and attempted to get a reading on my fuel tank sendor/sensor.

I went to 19 in the trip computer as I read there is a sensor in both sides of the tank. Then 6 (reading 234 very erratically) then 6.1 reads nothing of value at all.

Can anyone at all give me any advice on what needs to be done?


Regards


Simone.

[T-Cut]

Originally Posted by Shonkie

Hello everyone.
I have today found and attempted to get a reading on my fuel tank sendor/sensor.
I went to 19 in the trip computer as I read there is a sensor in both sides of the tank. Then 6 (reading 234 very erratically) then 6.1 reads nothing of value at all. .

Did you read through the additional notes I added to the original instructions?
Here's the bit relating to the floats. Maybe it will help?


Quote:

6 Fuel Level Sensor Outputs in litres (Fuel tank has left and right side sensors)
6.0 Fuel levels both (eg: 109330 means left half sensor = 10.9 litres; right half sensor = 33.0 litres)
6.1 Total tank level (eg: 0439 is 10.9+33.0 = 43.9 litres)
6.2 Indicated value with diagnostics: The Test Number (6.2) is preceded by 1, 2 or 3 (eg. 1-6.2 or 2-6.2 or 3-6.2)
If first digit is 1 - both sensors are OK. This is followed by three left signal digits, then three right signal digits.
If first digit is 2 - one sensor has an error. Side in error will display - - 0 . Functional side will show its three digits
If first digit is 3 - no sensor signal, no display. Probably - - 0 - - 0 (Needs confirming --- T-Cut)

EDIT 7 October 2019

Section 6
The following comments require a further update based on tests on Section 6 conducted by members during 2019. At this point, I haven't had time nor inclination to include this info, so the following is even more tentative.
************************************************** **************
Members who have had a go at this may have noticed that the routines for the fuel tank and sender units (Section 6) seem to be different from the instructions. Up to now, I hadn't ventured into the Test 6 part, but having now done so, I can report some observations.

Firstly, I think the instructions for Section 6 are wrong. I originally interpreted them from BMW documentation, from comments made on a BMW forum and from reports by members of the 75/ZT forums. In fact I now believe that the MGR version does not differentiate each sender's output, but simply displays an integral. It may well display a warning that one or both senders are faulty (the 1_6.2, 2_6.2 or 3_6.2 display), but more than that I now have doubts.

In my own case, the displayed figures under each of the Test 6 subsections were the total fuel content. This varied significantly in real time when the car was rocked side to side. This shows that the floats were responding to the changing liquid surface. The integral is given in litres. When I converted this to gallons and used the average fuel consumption shown by the OBC, the calculated range was identical to that shown by the OBC. This proves the figures are total content only.

I suspect the original instructions were basically what the BMW diagnostics system showed. The MGR version seems to have been simplified somewhat.


TC