Had the o/d electrical system tested & the governor talks to the relay, the relay talks to the solenoid (of course it was engaging during this time. I have now replaced the solenoid with a new one. I'll see what happens. Just took a trip to Dearborn, about 7 hours at 50 - 55 mph& it worked perfectly.
I continued using my relay ,I cleaned it up working great, I eliminated the governor,kickdown switch and the coil wire. cleaned up my solenoid so it was working as it should. Put a toggle switch between the relay and the solenoid . When you are ready just through the switch while accelerating and let off quick and back on you are in OD Reverse action to go back into standard. No problems unless you forget to take it out of OD when you stop. Cant back up ND IT MAY ROLL ON YOU. Have to always remember how it works so you wont make that mistake. I love my OD It will cruise at 75 with no high rpms. My rear end is a 373 so it will do around 2300 rpms at 75 Happy driving.
June 2014 took trip of 600 miles in 2 days. o/d worked fine. Car sat for 5 days then drove 50 miles working o.k. then o/d would not engage. Removed fuse from relay, pulled handle out. Drove 550 miles in 2 days without o/d. Then removed solenoid at home & it bench tested o.k. Replaced it with a used solenoid & it worked fine for 800 miles over 5 months. Now o/d will not engage again, just like before. Fuse on relay is o.k. Is the solenoid the problem?
Is your electrical system still 6 Volts? Battery Voltage is critical on 6 Volt systems. Check that the battery is charging above 7.0 Volts with the lights on high beam and the engine running above 1500 rpm. Too low battery or too much drop in the wiring to the solenoid will cause the solenoid to fail to operate the O/D unit. If the battery Voltage is good, connect one lead of a test Voltmeter to ground and run another wire from the heavy lead at the solenoid to the remaining lead of the Voltmeter. Monitor the Voltage (while operating the vehicle) when the solenoid turns on with the vehicle cold and then after it is hot. If there is a drop more than 1/2 Volt, you need to repair the wiring. One last problem is the engine idle speed. If it is too high the O/D may fail to engage. As noted in earlier posts check the rear section oil level (O/D is in the rear section of the transmission).