"The system monitors itself and a series of four different coloured lights indicate to the pilot all is progressing well with the start cycle."
The story was that the guy who originally designed the 'start sequencer' had died and no one knew why he had included some certain components in the circuitry.
There was a diode somewhere behind the instrument panel that, if it had blown, when the CWP (central warning panel) was tested for functioning lights, the engine would stop! The CWP was normally tested before engine start so the faulty diode usually never made itself known!
Luckily the first time someone tested the CWP with a faulty diode AND the engine running, he was parked on the ground!
The military simply got round the problem of the 'mysterious diode' by issuing a warning:
"Do not test the CWP in flight"