Hi Simon,
That is not how things should be.
I suspect that you have a problem with the way the throttle switch is wired
up.
The idea is that the parallels the dash switch.
The throttle switch holds the over drive in i.e. the throttle switch is
closed when the throttle is closed.
I suspect that your first problem is that the throttle switch is set such
that the contacts are open with the throttle closed and they close when the
throttle is pressed down.
So first disconnect both the wires from the throttle switch and, using an
ohm meter, set the linkage such that the switch contacts open as the
throttle is pressed down. They should open at around 1/4 throttle.
The next problem is that the switch, on the gearbox, which allows the
overdrive to engage in 3rd and 4th only appears to have been bypassed or the
plunger is stuck in. The circuit (wire) which goes to the overdrive solenoid
must pass through this switch before it goes to the overdrive solenoid. If
this is the case then connect the ohm meter across the contacts of this
switch and check that it closes only while the gearlever is in the 3rd or
4th position.
Michael Salter
http://www.netbug.net/blogmichael/
-----Original Message-----
From: owner-healeys@autox.team.net [mailto:owner-healeys@autox.team.net] On
Behalf Of Simon Lachlan
Sent: Wednesday, January 17, 2007 11:31 AM
To: 'Healey List'
Subject: Annual Overdrive Problem
God, I hate these overdrives. I could do with some advice.
I thought I could figure these things out, but I seem to be going round in
as many circles as the current in a functioning overdrive.
So, the symptoms:-
I sit in the car, engine off, gear lever in neutral with o/d in off
position. I then engage o/d and as soon as I just touch the accelerator
pedal I hear the solenoid's healthy clunk. (That's it coming on, right? I've
thought so much and fiddled about so much I've got myself completely turned
around!).
Push down on pedal..no further noise. Ease off until pedal is virtually
fully up, per above, I hear the clunk again. This makes for interesting
times on the motorway.
Eliminated so far, I think:-
1) Mechanical options....the mechanics are virtually brand new with plenty
of clean oil and it happens with engine running or not.
2) The dash board switch checks out OK.
3) The relay bench tests OK. (12 volts across terminals W1 & W2. The coil
operates and there is solid continuity between terminals C1 & C2 when it
operates.) Contacts within are clean and make good strong contact.
4) The system is fused and that's, obviously, OK.
5) There are no apparent wiring issues.
Main suspect is the throttle switch, though it - apparently - checks out
fine. I took it out and tested it. I got continuity on the meter where I
assumed the cam was on the lobe and no reading when I assumed it was on the
flat. (Note the use of "assumed".)
So, advice please. Am going away for a week off tomorrow, back to Ireland
without car which would dissolve in the rain). Thus grateful replies to the
torrent of advice may not be too prompt. But, I'm here now!
Simon.
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