Fails to crank over intermittinly

https://www.way.com/blog/p1682-code-meaning-causes-symptoms-and-fixes/
https://www.obd-codes.com/p0685
https://www.obd-codes.com/p0686

The most likely reason would be bad contacts on the starter relay or starter solenoid. You aren't getting enough amps to the starter.

https://shop.advanceautoparts.com/find/dodge-grand-caravan-starter-solenoid

Mitsubishi Grandis , year not old, no engine size told or VIN.
2003 to 2011 made, sure.
starter failing for any reasons is a simple thing, (unlike bad engines 50 ways to fail)
Battery must be good, load tested, did you know batteries can even be intermittent a hard fact of life, good ,back,weak or intermittent or simple not charged up.
or 10x more often battery lugs loose ,or rusty or BOTH>?>???>
jumper cables ,jump start any dead starter car>?????????
ok Jumps fail so we do what? now.
Your car has an automatic transmission. but some are 5speed manual transmission,s for sure. so I answer 2 times blind, sure
A/Tbox
the PRNDL switch bad for PARK cranking, we shift them all to N
to neutral and crank if this works PRNDL ,P switch is bad
car #2
if M/T tranny, the clutch switch bad kills the starter dead.
no sound means starter motor is dead , the tests are simple
one can have a car battery load tested for free in most shops and vast stores here in USA,did I say FREE, I did.
learn to use jumper cable
learn to start in N
if clutch pedal car, learn to short the 2 clutch pedal top switch wires and the starter motor goes BACK to working again or

if all tests fail we hot wire a starter motor, ask
and if that fails a new starter is replaced. (battery NEG lug pulled first)

electrical power you meant is seems good.
engine power zero.
starter dead.
this is no crank, ill post again,. for this, done so many times.

i use this thing called a voltmeter and avoid this jiggery pokery below...... time is money.

1: fuses good.battery terms clean? (all fuses, if you lack the FSM to see which ones are IN PLAY.)
2: battery charged to 12.6vdc reseted?
3: jumper cable cranking work now>? off a running donor car?
yes, the battery was dead, or weak, or discharged, test battery, test cars charging system and last make sure no drain on battery parked keys out of car..
4: NO, jump fails.
check or bypass clutch switch?
this cranks ok, (bad clutch switch at its pedal.)
if still dead it can be bad key switch or bad starter relay.
lets see if it has the relay. ,alldata.com says yes.

so does the starter relay close, cranking?
if not fix cause that first.
it needs fuses working
it needs power to the relay contactor input
power to the coil
and the coil enabling factor the clutch depressed and its switch must be closed.
and if the antithieft box, (factory option) is unhappy
the start relay coil will be dead.
start at the relay ,
does the (turned on) dash heater fan cut off, cranked
yes, then relay is closing
no, its not. find reason.
easy with a volt meter the 4 pins on relay.
pins 3,4,5,6
12v, 12v, 0v and 12v respectively.
if the pin 5 never goes to 0v, the immoblizer is unhappy.
sorry so small, Fixya shinks it to useless....

Have you replaced the starter ? You could use a meter to make sure the starter has battery voltage when it fails to crank.

Sounds like time for ignition switch. Don't hang a lot of trinkets and keys from your key ring. 2 keys at the most. I don't get the crank position sensor. I have never seen one go bad and has nothing to do with cranking the engine.

clutch sensor at the clutch pedal

sounds like a bad crank position sensor

If the engine fails to crank sometimes, you would need to have someone check for voltage at the starter when it fails to crank.
Could be the starter or several other things including the neutral safety switch or the key switch.

sounds like a loose wire on the starter