The lockout switch is on the left side of the tranny, at the top, near the
base of the shifter extension (basically, where the transverse 3rd/4th
selector rod can hit it). Sort of a mirror image position to the reverse
lamp switch, which it precisely resembles. In other words, completely
inaccessible on the vehicle, unless you have a Mk. I B and can remove the
tranny tunnel top (this is how I did it). Actually, I suppose there is some
chance you could reach up from below and touch it with your fingertips,
maybe unplug the wires, but I don't know about unscrewing it (unless it's
already loose, which if so could be the entire problem). Or possibly if you
remove the shifter boot and the shifter, you could see it through the hole,
but I don't know if you could do anything useful from there.
I think the idea of running an external wire from the column switch directly
to the solenoid, bypassing the lockout switch, is your best bet for
determining if the lockout switch is indeed the culprit. If you route it
safely, you could even go for a test drive on a hot day. You don't want to
pull the tranny just to monkey with the lockout switch if you haven't proven
it's the problem.
One might be tempted to peel back the tunnel carpet and cut an access hole
right on top of the silly thing, should it turn out to be the problem after
all. You could always screw a cover plate back over the hole; it would be
hidden by the carpet.
on 6/6/01 1:21 PM, Andrew B. Lundgren at firstname.lastname@example.org wrote:
> So I have never had this thing apart. I had it rebuilt at a shop. I am
> running the older newer OD (LH?) that was in the '70B. The OD works in 3rd
> and 4th, but the switch is on the column. Where is the lockout switch at?
> On Wed, 6 Jun 2001, British Sportscar Center wrote:
>> Max's theory does work. We've had several instances where the switch needed
>> to be moved closer by removing a washer, in order for it to function
>> correctly. We've also encountered switches which tested OK with an ohm-meter
>> and a test light, but which still did not activate the solenoid. Further
>> testing with a voltmeter showed that they must have been corroded internally
>> as they were passing only 4 or 5 volts. Replacement of the switch made the
>> solenoid operate and, therefore, the overdrive.
>> British Sportscar Center
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the red one with the silver bootlid.
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