1999 dodge ram van 3500 starter engages while engine is running only in park or neutral. Had to pull starter relay to disengage starter, also starter relay somehow connected to blower motor high speed

Here you go, Fuse 13.

Dodge Ram 1500 / 2500 / 3500 (1994-2001) fuses ...

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Fuse box diagrams (location and assignment of electrical fuses and relays) Dodge Ram Pickup 1500/2500/3500 (1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001)

1994-2001 Dodge Ram 1500/2500/3500 Fuse Box Diagram

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Nov 18, 2018 - Fuse Box Layout Dodge Ram 1500, 2500 and 3500 - 3.9L, 5.2L, 5.9L and 8.0L (Regular Cab, ... 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001)

Fuse box diagram Dodge Ram 1998-2001

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Jan 13, 2021 - Fuse and relay location. Fuse box diagram. Cigarette lighter fuse. Assignment of the fuses and relay Dodge Ram 1998-2001.

Question edited for funky spelling and punctuation.
Question moved to model category.

Jeff provides a great answer to the issue

• Jeff Armer Jan 02, 2023. Starter relay contacts stuck closed could be a reason .
• 
  Circuit Description
  Moving the ignition switch to the START position sends a 12 volt signal to the engine control module (ECM)/powertrain control module (PCM) Crank Request circuit. The ECM/PCM verifies that the transmission is in the PARK or NEUTRAL position. With the transmission in Park, voltage flows through the Park/Neutral position switch and feeds the starter relay coil. The ECM/PCM then grounds the control circuit of the starter relay. When the starter relay is energized it allows battery positive voltage to the starter solenoid S terminal. On some vehicles the starter will continue to crank the engine with the key released until it starts or the crank command has timed out to prevent excessive heat build up in the starter circuitry or the ECM/PCM receives an engine run flag.
  

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2000 dodge ram 1500 dash and taillights won't turn on

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El Fuso box

Fuse Box Diagram Dodge Ram 1500 / 2500 / 3500 (1994-2001)

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1998, 1999, 2000, 2001 - Here you will find fuse box diagrams of Dodge Ram Pickup 1500/2500/3500 1994, 1995, 1996, 1997, 1998, 1999, 2000 and 2001, get ...

If it is an automatic it is part of the Range sensor switch on the transmission where the cable hooks up from the linkage.

Dumb question but, did you check the trans fluid? A torque converter can hold 6 quarts of fluid or more and if the van has sat for an extended period of time the fluid drains from the converter and will come out of the vent tube causing a no movement issue

To clarify - the engine cranks then starts.
If it won't crank in any gear, I would check the neutral safety switch first.
You can also jumper the starter solenoid to make sure the starter will crank the engine manually without the circuit from the key switch.

You can test right from the starter relay ,located in the under hood fuse relay box . You want to know if the starter is good or bad or if the control side is the problem . Turning the ignition switch to start sends B+ voltage to the park neutral safety switch an through the coil side of the starter relay to ground ,if the park neutral switch is good . Try moving the gear selector into neutral to see if it starts then .
Looking at a wiring diagram would be a good first step in the diagnostic process. Free wiring diagram's here http://www.bbbind.com/free_tsb.html Enter vehicle info year , make , model and engine size . Under system click on engine then under subsystem click on starting . Click the search button then the blue link . Pull the relay an look at the bottom , you will see four numbers . 30 - 87 & 85 - 86 . Take a piece of 12 gage wire ,jump where 30 an 87 plug into the relay socket . If the starter is it will spin the engine over .

So what it only does it in park or neutral ! The vehicle starting circuit is only suppose to let it start in park or neutal . Park neutral safety switch won't allow B+ voltage to S terminal on the starter solenoid unless the vehicle is in park or neutral . It's probably the starter relay contacts stuck closed . You really should learn how it works before guessing as to the problem . Plus learn automotive electrical testing ! The ignition switch when turned to the start position send's a voltage signal to the PCM - engine computer .The PCM will energize the starter relay to crank the engine . PCM / ABS 10amp fuse in the I/P fuse box supply's B+ voltage to the park / neutral safety switch . When in park or neutral the B+ voltage goes through the control side of the relay to the PCM which will supply a ground to energize the starter relay .

that's internal engine repair so if you are not a mechanic you probably want to take this to a professional.

have you looked to see if the fuel pump is running?