Im workin on a 66 van need help

Shift motor on the transfer case, 4X4 control module, vacuum to vac solenoid. Did you hook up a scan tool an check for codes?

The electronic shift on the fly (ESOF) system is an electronic shift system that allows the operator to choose between 2 different 4-wheel drive modes as well as 2-wheel drive. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal pressed and the transmission must be in NEUTRAL (or the clutch pedal pressed in manual transmission vehicles).
When the mode select switch (MSS) on the instrument panel is turned, the 4WD control module (PCM) activates the electromagnetic clutch and powers the transfer case shift motor. When the shift motor reaches the desired position, as determined by the contact plate position inputs to the 4WD control module (PCM), power to the shift motor will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle integrated wheel ends (IWEs) are engaged and the electromagnetic clutch is deactivated.

Feature Inputs:
• Mode select switch (MSS)
• Wheel speeds (via CAN communication)
• Contact plate position inputs A, B, C, D (grounded when closed, open circuit when open)
• Transmission neutral
• Brake ON/OFF (BOO)

Feature Outputs:
• Transfer case synchronization clutch
• Transfer case shift motor relays
• Integrated wheel-end (IWE) vacuum solenoid
• Instrument cluster indicators (via CAN communication)
• 4WD mode (via CAN communication to PCM)

The transfer case (7A195) is equipped with a magnetic clutch, similar to an air conditioning compressor clutch, which is located inside the transfer case adjacent to the lockup sleeve. The clutch is used to spin up the front drive system from zero to vehicle speed in milliseconds. This spin-up allows the shift between 2H and 4H to be made at vehicle speeds listed in the vehicle owner's guide. The spin-up engages the front lock hubs. When the transfer case rear and front output shaft reach synchronous speed, the spring-loaded shift collar mechanically engages the mainshaft lockup hub to the chain-drive sprocket and the magnetic clutch is then deactivated. Shifts between 4H and 4L can only occur with the transmission safety switches closed. The vehicle's speed must also be within specified limits as determined by the Generic Electronic Module (GEM).
The electronic shift control system consists of a rotary switch control system, a GEM, a transfer case shift motor (7G360) with an integral shift position sensor, a clutch pedal position switch or digital transmission range (DTR) sensor, and a brake signal input switch.
There is a control switch located on the instrument panel for fingertip shift control.

Switch Control System
When the switch on the instrument panel is turned, there is a one second delay, then the electronic control module verifies the transfer case positions (2H, 4H or 4L). Next, the GEM looks at the shift position sensor and the digital transmission range (DTR) sensor or clutch pedal position switch (depending on transmission type) and brake pedal switch. If all conditions are correct to allow the desired shift, the electronic control module will tell the transfer case shift motor to execute the shift. After the shift has been made and the transfer case shift motor is off, the control module again looks at the shift position sensor to make sure the proper shift has been accomplished. Finally, the dash indicator light on the control panel will be illuminated by a signal from the GEM indicating the desired shift has been completed.
GEM
The generic electronic module controls the operation of the transfer case in response to inputs to the rotary control by the vehicle operator, the shift position sensor, the transmission range sensor and the brake pedal switch.

Vehicle Speed Sensor (VSS)
The vehicle speed sensor (VSS) (9E731) generates an AC signal which is sent to the instrument cluster (10849). The signal is used as input to the powertrain control module (PCM) and the transmission control module (TCM).
Shift Position Sensor
The shift position sensor, an integral part of the electric shift motor, tells the GEM module the shift position of the transfer case.
Electric Shift Motor
The electric shift motor, mounted externally at the rear of the transfer case, drives a rotary helical cam which moves the 2W-4W shift fork and 4H-4L reduction shift fork to the selected vehicle drive position.

does it jump out of gear or just doesn't go into gear in the first place ?

• 4-Wheel Drive Transfer Case Jumps Out of Gear

• Incomplete shift linkage travel.

• ADJUST linkage to provide complete gear engagement. ADJUST shift gearshift lever boot.

• Loose mounting bolts.

• TIGHTEN mounting bolts.

• Front and rear driveshaft slip yokes dry or loose.

• LUBRICATE and REPAIR slip yokes as required. TIGHTEN flange yoke attaching nut to specifications.

• Internal components.

• DISASSEMBLE transfer case. INSPECT sliding clutch hub and gear clutch teeth for damage. REPLACE as required.

the reason for hard shifting and selection when running is that the clutch shaft ( input shaft) is still turning even though the clutch pressure plate is released
it can be from oil/grease on the fly wheel /pressure plate face causing it to stick when hot
it may be from sticking clutch plate on the splines binding when hot
or it could be a dry spigot bush or failed bearing in the end of the crankshaft that positions the clutch shaft
check the pedal height adjustment and the position it is from the floor when starting to engage
It may be adjustment under the dash

Just a suggestion here but my son was experiencing the same problem with his Toyota Celica. We replaced the clutch and throwout bearing and MC, had me stumped for days the I pulled back the rubber boot on the MC where the it comes through the firewall under the dash and saw that there was fluid leaking into the boot so basically the MC was bad an it was bypassing the metering valve causing the fluid not to push the slave cylinder all the way down for engagement. On another car ...a 97 Saturn SL it wouldn't shift into gear, also all new clutch components. Wound up being a bad top right side motor mount was bad. engine was sagging just enough to cause the clutch not to shift properly. I hope this helps.

Depending on how old it is, I would say it has broken apart.
You won't really know until you pull the trans.

It seems you have a throw out bearing at fault, got to dis connect the transmission for that one

im assuming this is a manual transmission, if so you need to replace the clutch assembly. the clutch disk has worn too thin for the pressure plate to hold at higher rpms and soon wont hold at all.

if you can move it into gear when its not running, id say clutch,
but if it wont go in at all, then Im thinking shift forks or linkage

If your van has alot of miles, then just ignore it. Get a sevice done on it and let it warm up a bit and see if that helps the problem. When the miles get put on, especially with little maintaince, they have a hard time engaging "cold turkey". Another factor is that going from Rev to Drive(1st) you are going from energizing one accumulator to energizing two, and you're switching from the Rev clutch to the Underdrive clutch which tends to bleed off pressure the most.

that means the pin that the knob presses down is stuck on something. if you take the shifting panel off it showes everything. then there will be a plastic guide. see what the pin is sticking on and there you are.