I've recently been in communication with a couple of people on this. The
Haynes circuit diagram shows a TCSA microswitch controlling the TCSA only
*in addition* to the 4th gear only gearbox switch that controls both the
TCSA and OD. The Parts Catalogue also refers to both switches, but
indicates the microswitch is *not* on the gearbox, but does not indicate
where it is located or what operates it.
Kirk recently asked what was the function of the microswitch *on the
gearbox* that is in addition to the reverse light and (unused in his case)
OD switches. Then whilst writing to Don about the TCSA I suddenly realised
that if it only operates in 4th gear it removes the emissions advantage of
the change from ported to maifold vacuum and emissions would rise at idle
and in 1st, 2nd and 3rd. Then I wondered if the mystery microswitch was a
neutral switch that operates the TCSA, in addition to it being operated in
4th gear. And then I remembered that the gearbox *did* have just such a
neutral switch in late 72 for the short-lived sequential seat-belt system,
which was smaller than the usual reverse and OD switches and mounted right
at the front of the remote housing as Kirk's is. That switch was open in
neutral it is true, but it would be a simple matter to reverse the internals
of the switch for TCSA. Now maybe Kirk has a late 72 gearbox on his 77, or
maybe the mystery microswitch quoted both in Haynes and the Parts Catalogue
*is* a neutral switch for the TCSA and the Parts catalogue is incorrect in
saying it is not on the gearbox.
It should be a simple matter for someone with a fully functioning TCSA to
determine if it operates in neutral as well as 4th ... or maybe I'm the only
one who's interested :o)
PaulH.
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