[Healeys] overdrive problem

[Robert Blair]

Steve,
Sounds like you got lucky, and your dash wires behaved as the needed fuse.  I
suspect that there was a high resistance at one of the contacts in the switch
[switches are prone to failure] and the heat would be generated at or close to
the high R point [power=I2R].  if the switch got very hot and copper wiring in
the vacinity would get hot also as copper conducts heat well.  It was
obviously enough heat to break the copper circuit at that point.
New wire and switch obviouly shows that you were spared and melting elsewhere
in the circuit - exactly the role of a fuse.

Robert N. Blair  Yellow 65BJ8  rnbmail at yahoo.com
   



--- On Fri, 9/25/09, BJ8 Healeys <sbyers at ec.rr.com> wrote:

> From: BJ8 Healeys <sbyers at ec.rr.com>
> Subject: Re: [Healeys] overdrive problem
> To: healeys at autox.team.net
> Date: Friday, September 25, 2009, 11:12 AM
> No, Dave, I did not wash the engine
> bay.  Although the dash switch and its
> wires were the only things damaged in the meltdown, I don't
> see how the
> switch itself could have caused either the problem I was
> having or its own
> meltdown.  I've had overdrive dash switches apart
> before, so I know how they
> work inside. 
>
> I have a red warning light on my dash above the dash switch
> that serves to
> remind me to turn off the switch before backing up. 
> I've found that it is
> also a pretty good diagnostic tool for the overdrive
> electrics.  Before the
> meltdown, the switch was working just fine.  The light
> came on with the
> switch, but went off immediately when the switch was turned
> off instead of
> waiting for my foot on the gas, as it always did
> before.  It did this many
> times over a few days while I tried to troubleshoot the
> problem.  The dash
> switch and warning light were apparently working normally
> while the rest of
> the system was not.  In the past, the way the dash
> light operated was an
> indication that the throttle switch was either in or out of
> adjustment.
> This time, nothing I did would make the light stay on when
> the dash switch
> was turned off.
>
> Both the original relay and the new one worked the
> same.  I took the
> original apart, and it was fine inside -- no corrosion or
> other obvious
> defects.  I filed the points slightly to make sure
> they were O.K., then put
> it back together.  The system worked the same as
> before.  The only thing
> left to take apart is the throttle switch, which I will do
> if the problem
> recurs.  However, I haven't touched the throttle
> switch since before
> Southeastern and the problem has disappeared.
>
> Steve Byers
> HBJ8L/36666
> BJ8 Registry
> Havelock, NC  USA