RJohn50603@aol.com wrote:
>
> Looking for some net wisdom,
>
> I have a 1973 MGB. It has the standard four speed transmission, no overdrive,
> and two electrical switches. One is obviously for the back-up lights and it
> works. The other was not connected when I got the car. There are leads on the
> wiring harness and I hooked them up long ago. I just can't figuire out what
> it does. Everything seems to work either way. I can't find it on my wiring
> diagram for '72 - '73 either (or other years).
>
> What's it for?! Has somebody got a more accurate drawing or just know?
>
> R. Johnson - Dallas
R -
On my '79, the second switch is engaged only when the tranny is in 4th
gear. It operates a vacuum switch that (if wires and hoses were
connected) that would only allow the distributor vacuum advance to
operate in 4th gear. Supposed to reduce the emissions. Would this have
been there on the '73 model? I also seem to remember reading that it
might be used to keep the OD on an OD tranny from engaging except in the
top gear. At least, look at it as a spare backup light switch. Both of
mine are identical and interchangeable.
Wayne Kube
'79B
Plano, TX
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