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overdrive solenoid

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I have been repairing some inventive wiring by a PO. I repaired the hazard switch and hooked up the relay and now have functioning signal and hazard lights.

I also had to hook up the overdrive relay and the safety switches on the transmission earlier. Today I was checking the overdrive circuit before I put the dash back together and installed the transmission tunnel and the solenoid operated once and quit. I have power to the solenoid but it does not operate. Does anyone know what the resistance should be through the solenoid. I am reading 18.5 ohms. I guess I am hoping someone has a cure rather than buying a solenoid. BTW I had checked the solenoid several times when I repaired the wiring and it worked fine.


Thanks, Pete
 
Assuming this is an A-type OD, that means the pull-in contacts inside the top of the solenoid did not close for some reason. You can try carefully disassembling it and cleaning them, but generally it means it's time for a new solenoid.

With the plunger out (meaning the contacts should be closed), the resistance should be under 1 ohm. With the plunger all the way in (which is what opens the pull-in contacts), the resistance should be around 12-15 ohms (but 18.5 would likely still work).

If it's a J-type solenoid, just replace it. They should be around 5-7 ohms all the time.
 
I had a chance to go back and do some more checking. The solenoid will pull in but it will not come back to the off position. I can pull it back manually. It looks like there is a slot for a spring on the operating arm. Is there supposed to a spring? If not, what returns the plunger to the off position?
 
The only spring is way over under the plug where the pressure gauge goes. It presses down on the valve ball, which pushes the valve stem then the shin bone is connected to the leg bone and eventually it pushes the solenoid lever back down just a little bit. Far enough for the contacts to close, but nowhere near all the way to the stop.

In normal operation, there is also hydraulic pressure pushing the stem down, but you probably won't have that while testing. And it still won't push the plunger all the way to the stop. There is supposed to be some solenoid freeplay before the valve stem starts to move.

Generally the solenoid plunger will also fall of it's own weight (on cars with vertical solenoids), but it's not necessary.
 
The car is on stands and I still need to fill the brake and clutch hydraulic systems before I can engage the transmission.
I am in the process of putting the car back together after I got the body parts from paint shop. I am trying to get most of the mechanical work before I start putting the body back on.

Thanks, I will keep you posted, Pete
 
I removed the plunger and lubricated where it comes through the bracket and worked it a few times manually. Put everything back together and it seems to work fine now. I had the solenoid off earlier to replace a seal under the plate. I might not have had it aligned properly.

Thanks, Pete
 
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