Quiz time!

The calc for the indicators is based on speed and distance travelled.

 

Speedometer.

 

Ah. Posted mine before seeing that. Borrocks.

Stereo needs speedo to tell it when to turn up volume. Cruise control
obviously needs speedo to function. Self-cancelling indicators usually
work on time-distance, and for that they need the odometer which is part
of the speedo function.

 

Can I modify my comment on broken smoke machine, to one that perhaps
implies the smoke machine is the one working part left.

 

I thought he was after something non-obvious[a], like the neutral
switch shorted preventing the speedo reading or some other such Japanese
electwittery.

[a] It didn't even need (c) to point to the speedo.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
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KotPT -- "for stupidity above and beyond the call of duty".

 

That was the point of the (mechanical) clue.

 

Without looking at the other answers: speedo cable.

 

May one assume that 'AVC' stabds for 'Automatic Volume Control'? 'Cos
if it does, the typo is apposite.