>I posted this question while ago without getting any replies, so I try
>again...
>The od in my TR6 74 is engageable in all gears. Is the cause a wiring
>fault as I believe and how is the correct wiring sequence?
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First question, was it always like that or did it just start? The
overdrives as installed on later Triumphs have a switch on the top cover of
the tranny around the shifter rails that is actuated during third/fourth
and another for reverse. The third/ fourth switch allows the relay to be
energized when those gears are selected to allow the overdrive to function
in only those gears. The reverse switch is always in the on position until
you select reverse at which time it breaks the connection to the relay to
prevent you from engaging overdrive in reverse. This switch is wired in
series with the third/fourth tranny switch. The connection, or voltage
path would be as follows, from the + 12 volt (switched supply), to the
relay coil, to the overdrive selector switch, from there to the
third/fourth switch, then the reverse switch, then ground completing the
circuit. The relay and switch connections are not necessarily in that
order but the path would be the same. The actual switching of the voltage
to the solenoid is handled by the relay contacts. This way all switches
have to be closed, and the relay energized, for the overdrive to function.
This is all from my faded memory so if I missed anything I'm sure someone
will correct me. Anyway, if I recall that's how I wired mine. If you can
engage yours in all gears then either the 3/4 switch is stuck in the closed
position, the relay is stuck in the energized position (highly unlikely) or
someone wired this unit in without the safety switches in place -
Barry Schwartz (San Diego) bschwart@pacbell.net
72 V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (project)
73 Ford Courier (parts hauler, rain vehicle, getting a V6 soon!)
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