Hi Mike,
I agree with you except for one point. The throttle switch doesn't hold the O/D
at low revs. Kicking out O/D only depends on position of throttle. What I want
to say is when you drive at around 30mph in fourth gear O/D (thus meaning at
very low revs) with overdrive switch in 'normal' position the overdrive kicks
out by depressing the throttle pedal, regardless of the revs the engine is
doing. Maybe that is what you wanted to say, just wanted to clarify things up.
Regards
Eric BT7
Heinsberg, Germany
Hi, Simon and Dave,
I just had to look at mine on my BN2. I agree with Dave that the problem is not
the throttle switch directly. The reason I say this is that all the throttIe
switch does is to hold in the contacts C1 and C2 at low revs, with the O/D
switch off. The overdrive relay has to energise first in order to initially
close C1 and C2. IMHO it must be a wiring error for the O/D to come in at all
without the overdrive relay coil energising. If someone has bypassed the O/D
relay such that the power goes to the O/D solenoid via the throttle switch
only, this would give the symptoms you describe [although I think 1900 revs is
too high for the throttle swich opning setting -shouldn't it be about 1/5th
throttle?]
I added this in the hopes it would hlep rather than confuse!!
Best regards
Mike
Date: Sun, 16 May 2004 11:09:04 -0600
From: Dave & Marlene <rusd@velocitus.net>
Subject: Re: Overdrive jumping out
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.
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