Topic: 1951 Electrical Issue: OD vs lights


Jules51    -- 11-08-2021 @ 6:02 AM
  Have a problem: The OD works perfectly with the lights off. If lights are turned on after the OD engages, no issues. I can turn them on & off, while running, no issues. If lights are on and car comes to a complete stop, OD disengages and no issues with lights. Issue is when starting back up, the OD does not engage at the 24 mph, lights are not effected but OD does not engaged. I have to come to a complete stop, turn lights off, start back up and OD functions normally and turn lights back on, everything is functioning as should be.

Thanks
Jules51


Dan Duszkiewicz    -- 11-09-2021 @ 9:13 AM
  Jules, it sounds like you don't have enough electrical power to operate the lights and the pull in coil of the OD solenoid at the same time. The hold in coil of the OD solenoid takes less power than the pull in and works fine. The OD relay is powered through your ignition switch. Sometimes there is a voltage drop across the switch. You can try to bypass the ignition switch and see if the OD works with the lights on. To do this (disconnect the battery and follow all electrical safety precautions) on the OD relay mounted on your dashboard remove the wire connected to the 30 amp fuse. This wire is electrically hot with the key on so it is important to securely insulate / wrap with tape so it does not short out. Run a new 14 gauge minimum wire from the battery side of your starter solenoid to the terminal where you removed the wire from the 30 amp fuse. This will provide power to your OD solenoid whenever the battery is connected. This is a normally open relay so this power will not go anywhere until the governor completes the ground.
Drive the car and see if this works.

This is how my car is wired, I disconnect the battery every time I park the car for a couple of hours or more.


Jules51    -- 11-11-2021 @ 1:00 PM
  Ok I follow you and thanks for the response. However, is there another route to take? My generator is putting out volts, haven't measured the voltage from the voltage regulator. If your suggestion works, is there a fix besides your suggestion?

Thanks
Jules51


Jules51    -- 11-11-2021 @ 1:01 PM
  Generator is putting out 6.4 volts

Thanks
Jules51


carcrazy    -- 11-11-2021 @ 1:58 PM
  A service bulletin put out by Ford indicated that some cars came from the factory with the wire that runs from the relay to the solenoid being of too small a diameter which caused high resistance and low voltage at the solenoid. To solve solenoid engagement problems and improve overdrive reliability, it was recommended to replace the wiring in the entire overdrive wiring harness with 14 gauge wires.

Also, make sure the wires in the overdrive wiring harness are in good condition with no broken insulation, no bare connections, and that the terminal ends are clean, corrosion free and tight.

Check the voltage at the solenoid terminal #4. It should be at least 6.5 volts.


Jules51    -- 03-04-2022 @ 12:19 PM
  Mr. Carcrazy: Your information on the wiring for the OD on my 51 was right on. I got tired of the clutch chatter and changed out the Dennis Carpenter clutch system for a Ft Wayne IN system, what a major difference! So, while I had the room, I made a new wiring harness for the overdrive, complete from the relay to the solenoid, including the kickdown switch. I used 12 gauge for the wire, got the correct wiring color scheme from Ton's Performance. What a difference, even improved my dash lights brightness. Amp gauge is steady.
Once again, thanks........

Thanks
Jules51


carcrazy    -- 03-04-2022 @ 8:35 PM
  Congratulations Jules51! Sounds like you have solved your problems.


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