Only the earlier D-type used up to late 67 click in use, and even then you
have to differentiate it from the relay. On the LH-type energising it moves
it into the middle of its travel so it doesn't hit anything to make it
click. When you de-energise it it is only the oil pressure that pushes it
back, so after the first operation it doesn't move at all. The way to test
the circuit is to locate where the yellow connector in the main loom joins
the yellow/red in the gearbox loom. Part this connector and insert a
test-lamp. With the ignition on, the manual switch on, and the gearlever in
an OD gear the test-lamp should glow. With all other combinations it should
be extinguished. If no glow check you have 12v on the yellow in the main
loom with the ignition and manual switches on. If so move forward to the
gearbox inhibitor switch and solenoid. If not move back to the connector
for the manual switch by the steering column, and the switch itself.
A frequent cause of OD 'failure' is wear in the gearbox inhibitor switch,
sometimes this allows OD to engage if you pull the lever hard back into 4th
and hold it there. If so, there were usually two fibre washers under the
switch, or indeed the switch may be loose. Remove one of the washers and
try again. Getting at the switch is tricky, you have to remove the centre
arm rest, pull back the tunnel carpet, and remove the access plate on the
tunnel. Then support the rear of the gearbox on a jack and undo the rear
cross-member bolts and lower the jack. The switch is the one on the
left-hand side. Check the wiring is secure on the spades before doing
anything else.
PaulH.
----- Original Message -----
From: "Charles & Peggy Robinson" <ccrobins@ktc.com>
To: "Craig Tufty" <craig@ctufty.com>
Cc: <mgs@autox.team.net>
Sent: Wednesday, August 25, 2004 10:42 PM
Subject: Re: 72 mgb 1800
> Sure, apply 12 volts from the battery to it, listen for a click.
> > I fear that my overdrive solenoid may be defective on my 72mgb. Any
quick
> > ways to test it?
Check out the new British Cars Forum:
http://www.team.net/the-local/tiki-view_forum.php?forumId=8
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