I have recently converted my suburban's NP246 AutoCrap to a manual shift NP261HD. I am using the existing button to activate the front axle for now but I want to wire a solo switch and light. My Problem. The Actuator has 4 pins. Two grounds. One 12v and one 5v. How do I convert this to a basic switch? Is the power constant to the motor when off and constant when on? I am guessing the 12v retracts the actuator and the 5v releases it. I do know the actuator stays locked into whatever position it is in when power is disabled. But I am not sure how to wire this thing. Any suggestions.

Your best bet , take it to a qualified repair shop , before you replace more part's that arn't needed . Did you check to see if any DTC'S - diagnostic trouble code's are stored in the transfercase control module . Which transfer case does it have ? How many buttons on the instrument panel 4X4 switch ?
The NVG 236/246 transfer case features a 4 button shift control switch located on the instrument panel.
Do you know what a DTC is ?
DTC C0367
The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator's motor consists of a Permanent Magnetic (PM) motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit all within the actuator assembly.
The front axle actuator has four circuits connected to it, a front axle feed circuit, front axle ground circuit, front axle control circuit, and a front axle switch circuit.
Whenever a shift to AUTO 4WD, 4HI, or 4LO is requested, the automatic transfer case control module engages the front axle by grounding the front axle control circuit through a current limiting driver.
This DTC detects a shorted actuator, or a short to 12 V on the Front Axle Control Circuit.

Your vehicle can set a number of them .
DTC B2725
DTC C0300
DTC C0305
DTC C0308
DTC C0309
DTC C0310
DTC C0315
DTC C0323
DTC C0324
DTC C0327
DTC C0362
DTC C0367
DTC C0374
DTC C0376
DTC C0387
DTC C0550
DTC C0611
Without a professional scan tool an factory service repair info. you really shouldn't be trying anything , take it to a qualified repair shop.
The NVG 263 transfer case features a three button shift control switch located on the instrument panel.

New Venture Gear 263 Selectable Two Speed Transfer Case
The NVG 263 transfer case features a three button shift control switch located on the instrument panel. When the vehicle has the ignition key in the RUN position, the transfer case shift control module starts monitoring the transfer case shift control switch to determine if the driver desires a new mode/gear position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/gear position. The lamp will continue to flash until all shifting criteria has been met and the new mode/gear position has been reached (or has been engaged). Once the new mode/gear position is fully active, the switch indicator lamp for the new position will remain ON constantly.

Your vehicle had option of two different 4x4 systems ,
New Venture Gear 263 Selectable Two Speed Transfer Case
The NVG 263 transfer case features a three button shift control switch located on the instrument panel. When the vehicle has the ignition key in the RUN position, the transfer case shift control module starts monitoring the transfer case shift control switch to determine if the driver desires a new mode/gear position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/gear position. The lamp will continue to flash until all shifting criteria has been met and the new mode/gear position has been reached (or has been engaged). Once the new mode/gear position is fully active, the switch indicator lamp for the new position will remain ON constantly.
The NVG 263 transfer case provides the driver with 3 manual mode/gear positions:
• 2HI - 2 Wheel Drive high range
• 4HI - 4 Wheel Drive high range
• 4LO - 4 Wheel Drive low range
OR
The NVG 236/246 transfer case features a 4 button shift control switch located on the instrument panel. When the vehicle has the ignition key in the RUN position, the transfer case shift control module starts monitoring the transfer case shift control switch to determine if the driver desires a new mode/gear position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/gear position. The lamp will continue to flash until all shifting criteria has been met and the new mode/gear position has been reached, or has been engaged. Once the new mode/gear position is fully active, the switch indicator lamp for the new position will remain ON constantly.
If there are problems with electronic part of the systems the shift control switch light will flash warning of a problem , If no lights you have a mechanical problem in the transfer case itself .
The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator motor consists of a Permanent Magnetic (PM) motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit all within the actuator assembly.
The front axle actuator has four circuits connected to it, a front axle feed circuit, front axle ground circuit, front axle control circuit and a front axle switch circuit.
Whenever a shift to AUTO 4WD, 4HI, or 4LO is requested, the transfer case shift control module engages the front axle by grounding the front axle control circuit through a current limiting driver. Test Description
The numbers below refer to the step numbers on the diagnostic table.
Tests the electrical function of the front axle actuator. Helps determine between mechanical and electrical malfunctions.
Tests for proper power and ground at the front axle actuator.
Tests the operation of the front axle control circuit.
Helps determine if the transfer case shift control module is able to monitor the front axle switch.
Tests the front axle switch circuit for an open or high resistance.
Measures the voltage between the front axle feed circuit and ground.
Tests the front axle control circuit for an open or high resistance.
Inspects the front axle for a mechanical malfunction.
Tests for open in the front axle feed circuit.

u need a haynes manual for details or library sec629 has repairbooks

Rotors and brake calipers.

Hi Dale, Sometimes the front diff becomes wound up. I am not saying this is the problem with your vehicle but what I'm about to suggest may work as it often does with other four by fours. Make sure you have a clear space to drive the vehicle backwards and forwards at a slow speed. As you do so select the two high position on the selector. You may need to reverse and go forward several times. Hope it works for you. Regards John

Check the actuator cable that activates the front axle disconnect. It is bolted to the inner fender and the cable runs down to the axle. If you apply vacuum it should pull in and shift the interlock. To see if it is working, jack up the right front so the tire clears. The tire should rotate pretty free. Now engage the interlock. The tire should become harder to turn and the front drive shaft should turn. Now engage the 4X4 (with the trans in park) and see if you can still turn the tire. You shouldn't be able to turn it with the interlock activated.

Keep us upodated (remember to rate this answer).

Did you ever think of having it diagnosed by a qualified repair shop ? Thier are aspects associated with this system you have no clue about. That's the first thing every one goes for , changing the switch . It flashes because codes are stored .
DTC B0768 Service Indicator Circuit High
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0357 Park Switch Circuit High
DTC C0362 4LO Discrete Output Circuit High
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error
You need a professional scan tool to check for these codes an too view data parameters .
Transfer Case Shift Control Module
The transfer case shift control module uses the VIN information for calculations that are required for the different calibrations used based on axle ratio, transmission, tire size, and engine. The system does not know which calibration to use without this information.
The direct battery supply line (CKT 1640) provides the power to the module and motor circuitry.
Transfer Case Encoder Motor
The transfer case encoder motor consists of a permanent magnet (PM) DC motor and gear reduction assembly. It is located on the left hand side (drivers side) of the transfer case. When activated it turns the sector shaft of the transfer case (clockwise or counter clockwise) to shift the transfer case. The encoder motor is controlled with a pulse width modulated (PWM) circuit within the transfer case shift control module. This circuit consists of a driver on both the Motor A and Motor B circuits. The encoder motor is bi-directional to allow the motor to shift the transfer case from 2HI or 4HI to neutral and 4LO positions.
Transfer Case Encoder
Your best bet ,take it to a qualified repair shop .

There is a front differential actuator on the side of the front axle housing .. select 4x4 inside the cab and check for 12 volts with a test light at the plug for the actuator. If you have power and ground when in 4x4 the actuator has failed ( common ) . If there is no power it is possible they did no plug everything back in on transfercase and left a harness unplugged or damaged. Let me know what you find and I can help further.
Good luck.

The vacuum shift motor ( actually a diaphragm ) is a vacuum to move the lever one direction ( i.e. 4WD ) and then vacuum to move the other direction ( i.e. back into 2WD ).

You can shift into 2WD and remove the vacuum lines and plug them to remove this, if you think the vacuum shift solenoids are getting ground from another source and shifting the front axle, or just unplug the connector on the shift solenoids. The GEM activates the Shift solenoids by applying ground to them.


I would have to agree with papa_11069 that the problem is in the front u-joints.

I had the same problem with the shift on the fly push-button 4x4 on my 97 Suburban. GM Shop manual indicates that it could be due to an encoder error on the actuator motor. Try pulling the transfer case fuse to reset the transfer case control module. Wait at least one minute. Re-install fuse then re-try operation. Did it last week and that saved me a trip to the dealership and extensive troubleshooting.