Hi Simon,
I don't remember which model car you are having trouble with. If it is a
BN2 or later this will apply.
It appears that the solenoid is being controlled by the dash selector
switch plus throttle switch only -- that the OD relay is not functioning
due to a relay problem or wiring problem. Either the relay coil
connected between W1 & W2 is not operating or the relay contact between
C1 & C2 is not making contact. I am attaching a schematic drawing with
explanation of how the circuit works. This list will remove the
attachment for all other recipients.
Operation of the relay coil can be checked by applying 12 volts to
terminals W1 & W2. If the coil operates, there should be solid
continuity between terminals C1 & C2. The relay itself can be opened by
removing it's cover. The contacts can be carefully cleaned. Or the relay
itself may be defective & not repairable. Any problems other than the
relay will likely be loose connections, broken wires, or mis-wiring.
Dave Russell
BN2
Simonlachlan@aol.com wrote:
> Hi, I am back from a short break and have yet to apply myself to the
> overdrive issue. See below
> ""One for the gurus....
> Background first:-
> I have all new overdrive mechanicals which worked fine until just recently.
> I have a 28% ratio o/d unit.
> Plenty of good clean oil in gearbox, first thing I checked.
> Overdrive on/off switch is new and works fine.
> Switch on gearlever is not new but works fine.
> I have not messed around with carbs or related linkage.
> Solenoid sounds healthy and engages overdive firmly.
> (I have a 3:54 diff, so the revs may seem a little low to you, especially
> coupled to a 28% o/d)
>
> So, the symptoms
> If I am driving along at about 1,900revs with my car in overdrive/4th,
> she'll jump out of overdrive if I raise the revs/speed with the accelerator.
> If I then decelerate back to 1,900 (+/-) she'll pop back into overdrive.
[demime 0.99d.1 removed an attachment of type image/jpeg which had a name of AH
OD.jpg]
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