S10 4 wheel drive dash lights out

You have a switch on the instrument panel ?
The NVG 263 transfer case features a three button shift control switch located on the instrument panel
The NVG 236/246 transfer case features a 4 button shift control switch located on the instrument panel.
Or
The New Venture Gear (NVG) 261, RPO NP2 transfer case is a two-speed, part-time with "mode shift-on-the-fly" capability. It has a chain driven front output shaft and an epicyclical low range planetary arrangement. The NVG 261 transfer case features a four position shift lever control located in the vehicle floor plan. As required, the operator can select 4HI position from 2HI "on-the-fly," as described in the owners manual. A dash 4WD lamp will continue flashing during shifting, until all criteria have been met and the new mode/range position has been reached. Once the new mode/range position is fully engaged and the front axle disconnect locks in, the dash light 4WD indicator lamp will remain ON constantly. Range shifting functions similarly, although it should be limited to speeds 8 km/h (5 mph) or less.

Remove the actuator motor assembly from the transfer case and try to manually engage the transfer case, if it is easy to engage then the actuator is the problem.

Which do you have ?
Transfer Case - NVG 236 (Two Speed Automatic)
Transfer Case - NVG 233-NP1 (Two Speed Selectable)
The NV236 transfer case is an automatic transfer case with three drive ranges. Shifting from rear wheel drive to four wheel drive is done automatically when the transfer case shift control module receives wheel rotating slip information from the speed sensors. The transfer case shift control module then engages the transfer case motor/encoder to position the transfer case from rear to four wheel drive. When the transfer case shift control module receives information that the wheel rotation is the same on both axles, the transfer case shift control module sends position information to the motor/encoder to put the transfer case back into rear wheel drive. The three drive ranges are 2HI, 4HI, and 4LO. The 2HI position is for normal driving with the rear wheels pushing the vehicle. The 4HI, position is for driving through sand, snow, mud, gravel, or heavy rain at normal or slightly below normal speeds. The 4HI engages the front axle to allow for four wheel drive. The front axle is pulling the vehicle, and the rear axle is pushing the vehicle. The 4LO range is used for off road driving, heavy snow, deep mud, or shallow fording. The 4LO is similar to the 4HI except that the gearing in the transfer case is set for low speed and high torque. The NV236 is manufactured at Syracuse New York by New Venture Gear a division of New Process Gear for General Motors.
Is the switch light on or flashing ? If you have automatic 4x4 there are several DTC'S that can set >
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 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

Someone will have to go under and check the linkage is working when the 4 wheel drive is fully engaged and not just moved to a neutral position.

Depending on the make and model, it could be the control switch on the dash or the switch that moves the gears in the transfer case.

Check the 4x4 wiring ground (directly behind the left front tire, mounted to the body). If the front axle actuator is still good, this is usually the source of frustration. Put some RTV Gasket sealer on the nut and bolt after you replace them to help keep it from corroding as fast.

First, start checking the fuses an there is also an electrial activaced switch at the transmission or transfer case that may be bad.

95-96
Your control knob should say 2wd, 4auto, 4low.

First, we need to narrow it down to a transfer case issue, or a front axle issue.
Step 1) Jack up the front end and place it securely on jack stands.
Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels may or may not turn. Do not be alarmed if they don't turn. This is normal for your vehicle.
Step 3) Start the vehicle and let it idle. Place your foot firmly on the brakes, place the transmission in NEUTRAL, engage 4low, then place the vehicle back in park. DO NOT ENGAGE ANY GEAR!! The lurch as the transmission engages could cause the vehicle to lurch and potentially fall off the jack stands.**If you can turn the front driveshaft, the transfer case is not locking. This could be due to a mechanical issue with the transfer case itself, or an electrical gremlin with the control system. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4) With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If both wheels spin in opposite directions, then the front axle *should* be properly engaged. Take it for a test drive (after safely lowering it to the ground, of course). If the front wheels do not spin in opposite directions, there is a problem with the front axle. This could be due to a mechanical problem with the diff, or a failure of the center axle disconnect to engage the passenger side axle shaft. Start a new thread with the results of your checks, and we'll go from there.

Troubleshooting the CAD on a 95-96 is a bit more involved than I want to get into here, and the problems can vary widely. This'll get you started.


97-01 4-door and 96-00 Sports
Your control knob should say 4auto, 4high, 4low.
First, we need to narrow it down to a transfer case issue, or a front axle issue.

Step 1) Jack up the front end and place it securely on jack stands.

Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels should turn. (If only one turns, don't be alarmed. One wheel sometimes has more resistance in the brakes, bearings, or CV joints. This is normal)
Step 3) Start the vehicle and let it idle in PARK. Engage 4high. DO NOT PUT THE VEHICLE IN GEAR!!! Crawl underneath and see if you can turn the front driveshaft.
**If you can turn the front driveshaft, the transfer case is not locking. This could be due to a mechanical issue with the transfer case itself, or an electrical gremlin with the control system. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4) With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If both wheels spin in opposite directions, then the front axle *should* be properly engaged. Take it for a test drive (after safely lowering it to the ground, of course). If the front wheels do not spin in opposite directions, there is a problem with the front axle. Start a new thread with the results of your checks, and we'll go from there.


'01-'03 Sport and '01-'05 Sport Trac
Your control knob should say 2wd, 4high, 4low

The transfer case in these trucks functions essentially like the 1st-gens' 13-54 t-case. (i.e. it uses a lockup collar engaged by the transfer case shift motor) The troubleshooting procedure is very similar, but you don't need to worry about hubs or center-axle disconnects engaging.

Step 1) Jack up the front end and place it securely on jack stands.
Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels should turn. (If only one turns, don't be alarmed. One wheel sometimes has more resistance in the brakes, bearings, or CV joints. This is normal)
Step 3) Start the vehicle and let it idle in PARK. Engage 4high. DO NOT PUT THE VEHICLE IN GEAR!!! Crawl underneath and see if you can turn the front driveshaft.
**If you can turn the front driveshaft, the transfer case is not locking. The shift motor could be falsely reading an incorrect t-case position, or it could be a mechanical issue with the case itself. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4) With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If it does, the system should be properly engaged. Safely lower the vehicle to the ground and take it for a test drive. If the wheels do NOT spin in opposite directions, there is a problem with the front differential or axle. Start a new thread with the results of your checks, and we'll go from there.


Keep us updated.

Check actuator under battery to see if it moves when you put in 4 wheel drive.This has an arm on it which pulls a cable in on front diff.sometimes the actuator boot will tear as it is like a rubber boot.

the light is flashing to let u know a fault has occurred in the transfer case electronic control system, most likely the transfer case engagement motor

Theres a vacume dash pot under the battery box. It pulls a cable that engages the front diff. Put the vacume line and you'll have lights and four wheel drive. (it happened to my blazzer)