Hi Justin,
The OD solenoid has two coils, a pull in coil which draws about 15 amps,
& a holding coil which draws about two amps. Both coils are energized
until the plunger reaches it's full operated travel. At this time, a
contact on top of the solenoid (under the rubber cap) opens to remove
power from the pull in coil.
From your description, the pull in coil is not operating, but the
holding coil is operating once you give it a bit of help.
Either the pull in coil is defective, or it's cutoff contact is not
making the circuit when the solenoid is de-energized. Cleaning the
contact might cure the problem.
As to the last part of your description, the solenoid plunger can only
work through a limited range of travel. With it installed, the plunger
drop is mechanically limited to a range where it can work. With the
solenoid removed the plunger may be extended too far for it to work.
With the rubber cover removed, measure the resistance of the holding
coil, about 6 ohms. The pull in coil should measure around 0.8 ohms.
The contact, when closed, should measure zero ohms.
Dave Russell
Bn2
Justin Laborde wrote:
> I have a 1961 BT7 that has not been able to engage overdrive since
> I've been driving the car. I've read a lot of the previous messages
> about the overdrive and thought I'd like to take this project on and
> get it working again.
>
> Everything seems to be working normally all the way up to the
> solenoid. I have 12 volts going to the solenoid only when the car is
> in 3rd or 4th gear with the driver switch moved to overdrive. When I
> move the driver switch back to normal I still have 12 volts going to
> the solenoid (so far so good), now when I press the gas pedal I get
> 0 volts going to the solenoid. This is exactly how I remember my dad
> using the overdrive, except back in the day it worked.
>
> I pulled the transmission tunnel to take a look at the valve setting
> lever. When I switch the overdrive on it either doesn't move at all,
> or moves just a bit. If I give the lever a nudge it will turn and
> line up with the hole in the overdrive. At this point the valve
> setting lever will hold tight (I have overdrive!) until I press the
> gas pedal and moves back down to the original position. I cleaned
> the area of the valve setting lever and it seems to move back and
> forth smoothly by hand when the system is off however I still
> couldn't get the solenoid to move the lever.
>
> Next I pulled the overdrive cover that is below the solenoid. Again
> no or very little movement of the solenoid when powered. Just like
> the valve setting lever I could give the solenoid operating lever a
> little bump up and it would hold until the gas pedal was pressed.
> There didn't seem to be any abnormal drag in the system so I decided
> to pull the solenoid out and check independent of the overdrive.
>
> With the solenoid out of the car I wired it straight to my battery.
> Now I can't get it to do anything at all. No movement, nothing.
> Maybe I'm missing something here? Has anyone else had a similar
> experience? Are there any other checks I should make to my solenoid
> before I bury it in a shallow unmarked grave?
>
> I want to make sure I haven't missed anything so I don't needlessly
> spend money on a new one.
>
> Thanks for the help!
>
> Justin Ypsilanti, MI
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