jim p
low atf will not

John St.Louis
no but a misadjusted neutral switch will

rickinmn
If the level is low enough that the transmission seized, that would prevent the engine from cranking. But it would have made a LOT of noise and stopping working before it got to that point. Rick I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology. Visit my blog for cool articles and TSB's:

T J
If it's "low" I'll say no. Totally evaportated, maybe yes, but remember this is transmission fluid for shifting. You're not doing that when starting. Driving might be another problem. But no, low ATF is down on the list for things to check for when trying to figure out why a car won't start. And on edit: the two things that keep a car from starting are spark and fuel. Either it's not getting fuel (fuel filter clogged, pump is shot) or it's not getting spark (electricity), meaning anything from the coil to the spark plugs. It could be a variety of things, but I doubt it's your AT fluid.

Honey
Low trans fluid has nothing to do with the engine cranking over. Is your battery dead? When you turn the key do you get a dome light or any interior lights that normally worked before? Does the starter click or make any noise when you turn on the key? How old is your battery? Got a battery charger or any way to test it to see if it's any good? If you're not sure you could try jumping it. Positive(red) to positive and negative to negative with those jumper cables otherwise you could cause damage. Make sure you turn off everything in the van - lights, radio - anything that uses juice - while you are trying to jump start it. How did it die on you in the first place?

Nomadd
Nope. It's more likely that neutral safety switch you just replaced.