Okay, I followed carringb's advice and disconnected the trans controller harness this morning. No change.
I did, however, see all this dirt/grease in the connector that's mounted on the trans. Do you think it could be the problem? If so, any ideas on how to clean it out?
This was the cowl ground strap as I found it...
I thought the exposed wire might be the problem so just in case I re-taped it...
This was the mounting hole and bolt. Could so little rust be the issue?
Here's where that strap mounts to the motor. Could the old oil be an issue?
Here's the frame ground strap. Dirty, but I doubt that's the problem?
And finally, the shift solenoid. Looks like it got dragged on the ground at some point. Could it be the culprit?
By the way, I also disconnected the harness at the solenoid just to see what would happen. The van wouldn't start.