Monitor the voltage at TB11-5 and TB11-6 while under a load. The (2) two brake switches (one underneath the floorboard and the other on the drive motor brake asm bracket) will show good voltage with no load and will show a voltage drop under-a-load,if one or both are bad.

Went back to the customer yesterday and did some more troubleshooting, as I am always reluctant to replace the oscillator card since the are very rarely the problem.

Upon further investigation I found that the contactor was indeed getting a negative from the boards, but the positive from the driver board was on occasion dropping out and or not carrying appropriate amperage to pull the contactor in. I jumped across the board (direct from the brake switch input to the contactor output) and bingo the truck started working.

This isn't the first time I have had this type of problem with one of these driver boards.

And correct when attempting to operate the truck the display was showing a blank screen as if the truck should be operating.

I would never say that the card is "for sure good", based on this test procedure, but I would think it proves the display is able to see and display an error code when 1 is active, so then it means there must be some other strange problem, since the card should also display some code, any time it does not run, and if it does run, it should then output the current battery state of charge to the same display.
what does the display say as you try to drive, just blank? (have you turned the key to the "start" position, some crowns have a rely that the start position pulls in?)
does the display show the sequence for the reach selector?

Correction 1C3645LXCD1