Ok thanks Gouli, happy to explain that;
I 'recently' saw a report about a crash at a motorway toll booth where a vehicle ran into the back of another that was waiting to pay at the booth. The defence case was that the person driving the moving vehicle braked but nothing happened. It went to forensics to find out if she had in fact braked or not … she had, the brake lights were on for a period of time before impact with was also backed up by CCTV. I think this led to a recall for the car type due to a brake problem.
My point;
As you highlight from page 58;
Warning unit testing
Testing of the warning unit at the manufacturer’s facility showed that all the indicator lamps operated correctly, using both the bright and dimmed settings.
Initially, the unit drew more current than normal and did not generate the required audio attention-getters associated with the visual warnings. After a few minutes of testing, one of the tantalum capacitors, connected across the power supply of the audio amplifier, partially disintegrated. Subsequently, the current used by the unit returned to normal and the audio attention-gettersoperated correctly.
But what did we really need to know about the lamps?
Lamp Examination to Determine On or Off in a Collision
http://www.harristechnical.com/articles/lamp.pdf
"Do not, under any circumstances, turn on a vehicle's lights after an accident in an attempt to determine if they were functional at the time of the collision. This one act may very well destroy the evidence you are seeking.
.
.
In a lamp with two filaments, if one is incandescent, the hotter of the two will deform more than the other. "
So, I now hear DB asking, 'with no visual or audio warnings presenting themselves, how was it that they were acknowledged?'
Well perhaps it was the action of the
Fuel caution being cancelled that also cancelled those
Low Fuel warnings, there's no time line to say how long the warning lights were on for before acknowledgement.
Now, this was a manufacturers test of the warning unit and they were probably tasked to determine if the system was functioning correctly and
not necessarily whether the lamps were on at the time, or not. If a filament examination did take place to determine whether the lights were on for such a long time before impact (15 mins), it isn't in the report.
Which then leads us down the path as to why/how it was that the warning light went out when the warning was acknowledged, because surely the fuel level in supply tank 1 was still low after the acknowledgement because if you believe what DB tells us, you can't gain fuel.