So the humble dash voltage stabiliser for the instruments.. I believe the B and I indicate 'battery' and 'instruments' as input and output and that the majority of wires associated with it are green or green with a black stripe.
But how does it work essentially? I was thinking that the charge from the battery comes in goes out more stable to instruments yet many of the on-line pictures seem to have wild connections that don't agree. On my one I can only see green cables daisy-chaining to instruments essentially, wondering where it obtains it power then. Or does it emit some special stabilisin force field that radiates in every direction

 

The solid green is 'key on' voltage via a fuse.

The voltage stabilizer is likely just a bi-metal switch that constantly opens/closed to produce a reduced 'average' output....which is probably about 8 volts or so. This prevents the gauges from swinging in reaction to voltage rise/falls in the rest of the electrical system. Usually used only for fuel and temp gauges but I'm not sure about the Jaguar installation

Cheers
DD

 

As I recall (vaguely) from my e-type days, the regulated and "steady" DC output voltage is 10V, regardless of alternator output or voltage at the battery. Doug's correct, the rapid opening and closing of the regulator contacts is achieved by using a heated contact that flexes to open the output - 0Voutput, then cools rapidly and closes again giving alternator/Battery voltage ?V output then the whole cycle begins again. The resulting average output between zero and full output voltage is seen by the instruments as a "Constant" supply. Again, I recall 10V DC output, but 10.2V is in the back of my mind.
On my e-type I replaced it with a $2.00, 10V (or was it 10.2V) output transistor installed in the original case. Rock solid and cheap and worked a treat and no more gauge issues.

 

This from Moss.
https://mossmotors.com/131-556-solid...ositive-ground

 

the little green daisy chain of wires seems to have three heads and there are five gauges so someone misses out...