Van will not crank or start

Battery ground and positive cables have to be in good shape. Do any electricals work, dash lite--headlites--radio--anything? If only problem is the starter motor, then check voltage and ground for starter motor. Any testing, make sure tranny is in park or neutral and parking brake is set.
The starter motor usually has two voltage circuits, one comes from battery, hot all the time. the other circuit usually goes hot with key in the crank position and is wired through neutral or clutch switch, depending, through possible relay.
To look up wiring diagram, I need year--make--model?

Check the grounding from the starter, in fact, check all the heavy ground wires, put a multimeter across the starter too.. but always check fuses first as an added precaution, check your ignition wires are sound (is the key loose in its cylinder ?) sounds like grounding though....having replaced those two components, are all the wires solidly connected... good luck Red.

I think you're over your head here. Take it to a professional mechanic and let her sort it out. Sounds like your alternator isn't putting out the correct voltage.

You replace parts as part of your preventative
maintenance program,not to solve a problem
When working on a problem only component testing
will find the issues
You need to check for fuel pressure at the motor with a gauge
You check spark with a test plug you buy,not ground a plug
or wire on the vehicle
You can check for compression or cylinder leak down
to test some mechanical issues
I would assume ALL Fuse & links have been checked,as
well as battery voltage 12.6 v or more & cables etc
The ignition switch could be bad,turns starter but not all
the internal contacts are good

Turn the headlights on and watch them while the key is turned to start. If the lights go out, one of your cables or connections at battery or starter is not good. If lights dim a lot but stay on, possibly a bad starter, it needs testing. If lights aren't affected by cranking position, turn lights off, pull the small wire off the starter solenoid, hook up a test light to ground and to the solenoid wire. Light should come on when key is held in crank. If it does, likely a bad starter solenoid. If no light, then the start circuit from ignition switch to starter solenoid is not working. Check for power out of ignition switch on the start wire with key in crank, to begin with. If powered, switch is good, need to check if neutral safety switch is good, and then check or swap in a new starter relay.
Post back with any results.
Good luck.

id make sure the fuses and relays didn't pop for the starter while installing as if it was intstalled wit the battery still connected it could have arched it causing them to blow. then id make sure the battery was good and so was the alternator first thing. second, make sure all ur connections are good ie battery ground as well as wires on the starters solinoid.

Just maybe the battery and alt were good. You did test them,before replacing didn't you? How about the starter solenoid,starter or ground connections or cables with too much resistance. Do a voltage drop test, on all grounds, you can get to.

sir try to check ground connections

First thing I would check is to see if you have power at the trigger wire of the starter motor while someone is trying to start the vehicle for you. It will be a Yellow with a light blue trace. If you do then I would check to see if the main battery cable has power to it all the time when someone is trying to crank it. If it does then I would hold a test light on the case of the starter motor and have someone try to crank it. Make sure that the ground you use for this test is on the negative battery terminal not just anywhere on the car. If the test light lights while you are cranking it then you have a bad ground. Hook up a set of jumper cables from the battery negative terminal and clamp it directly on to your starter motor and see if it starts. If you check it and the test light doesn't light up and all the other checks are good then your starter motor has failed. If one of the other tests has failed then you have a starter relay problem or something else. let me know what you find out.

we get remans bad out of the box......... good luck