In a message dated 98-10-15 12:13:19 EDT, mysmithnc@worldnet.att.net writes:
> My overdrive doesn't. If I mechanically operate the lever, the OD kicks in
> and out properly, but I don't get any satisfaction, electrically. The
relay
> will click when the electric switch is operated when in appropriate gears,
> but the solenoid ignores me.
Mike,
Well, the relay clicks, so that helps a bit. Thats a good place to start
trouble shooting.
1) When the relay clicks, check to see if you have 12 volts on the
yellow/purple wire at the relay. If you do, go to step 3); if not, go to step
2).
2) check for voltage at the brown/white wire at the relay. If you have voltage
here, the relay is bad; if not, there is a break or a bad connection in the
brown/white wire. Repair or replace as required.
3) With the relay energized, look for voltage at the yellow/purple wire where
it connects to the solenoid. If you have voltage here, the solenoid is bad; if
not, there is a break or a bad connection in the yellow/purple wire from the
relay.
> If the solenoid is bad, can I repair it? How can I test the solenoid and
> relay for proper operation? Is there a common kludge- I mean modification
-
> for installing a manual operating lever?
There are two possible failure modes with the solenoid - mechanical or
electrical. If it is mechanical, it may be clear from a visual examination
what needs to be done. If it is electrical, there are about three
possibilties. The first is a break or bad connection where the solenoid
windings connect to the outside terminals. The second is a failure of the
windings - either an open or a short. On the TR4A, I believe you will find two
windings inside - one heavy duty to pull in the solenoid, and a lighter duty
winding to hold it in place after the heavy duty winding has pulled it in. The
third possibility is a failure of the switch which cuts out the heavy duty
winding once the solenoid has engaged.
If it is the terminal connections, you may be able to clean and re-terminate
them. If it is the windings, you will need to rewind it. This is a pretty big
undertaking for the home hobbyist. If you want to try it, take the solenoid to
an electrical motor repair shop in town, and see if they will sell you the
proper wire for it (and get any advice they may be willing to offer). Make
sure you get the exact same size, insulation type, etc. Unwind the old one,
and pay very close attention to the way it is wound. Rewind it exactly as the
old one was, down to the last detail. If the windings are randomly laced, do
the same; if they are very orderly, make yours very orderly. Make yours the
same number of turns as original. A little descrepancy probably won't hurt,
but try to get as close as you can.
If it is the switch, It might take nothing more than a good cleaning to fix
it.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/index.html
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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