4wd engages but vehicle bucks like 4wd is slipping.

4wd tries to engage and works sporadically. Vehicle bucks in the three 4wd modes.

My car has 136000 miles.
My car has an automatic transmission.I also tried taking out fuses 8 and 48 and put back in with no change.

Experienced mechanics share their insights in answering this question :
There is likely an internal issue going on within your transfer case. The most common cause of transfer case slippage is low fluid. I suggest that the transfer case fluid condition and level is checked. If the two wheel drive mode works just fine then it is more than likely there is a fault in the transfer case not the transmission itself. I also suggest that a technician check the shift linkage from the 4 wheel drive shifter to the transfer case. Make sure it is still in proper adjustment. Another way you could test the transfer case is by removing the shift linkage and moving the transfer case through the four-wheel-drive functions by hand. If they feel any trouble with it going into the separate gears then that helps further indicate that it is a transfer case issue. Usually a four-wheel drive fault will come with some type of indicator other dashboard and or a code stored live in the vehicle computer. A technician such as those we provide here can run a scan diagnosis on the transmission module of your vehicle to get some clues as to what the problem could be. I will ask customer service to send you an estimate for a four-wheel drive malfunction diagnosis.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Faulty Switch – If the switch itself is bad, it won`t let current flow from the battery to the solenoid, and won`t allow the transfer case to engage four-wheel-drive. Even if the switch feels fine, it could be corroded, dirty, or broken internally.
In this situation, you will need the transfer case to be replaced. If you are wondering can bad transfer case damage transmission, the answer is yes, sometimes. Both are part of the drivetrain, and in the case of a serious transfer case failure damage to the transmission and other parts of the vehicle may occur.
Have someone stand outside of the car and watch the tires. As you drive into the tree, your tires will try to get traction. If all four wheels of your car are moving, your four-wheel drive is doing its job!
When 4WD is engaged, the locking hubs lock in the front wheels to the front axle allowing them to get torque from the engine. On older 4WD vehicles, manual locking hubs were standard. You`d have to get out of your vehicle and turn a knob on the front wheels until the hubs were locked.
Move the vehicle straight forward about 10 feet to allow the front hubs to engage and lock. Turn your wheels all the way to one side and drive forward. You should feel the vehicle bind or resist rolling forward smoothly. If you can not feel the vehicle resisting during the turn then your 4WD is probably not working.
A damaged fin or bearing in the torque converter can cause hesitation in the transmission shifting, or the transmission to slip out of gear entirely. This is because the engine torque is not being efficiently converted into the hydraulic pressure needed to shift gears within the transmission.
Don`t try to engage these 4 wheel drive systems when the vehicle is moving or you can damage expensive components. However, most 4WD systems can now be shifted into or out of 4WD on the fly at the push of a button. The most sophisticated 4WD systems are fully automatic.
Full-time 4WD powers all four wheels, all the time. To get around that problem of transmission wind-up, mentioned above, the system employs a centre differential (or simply diff), which allows a different speed for each axle.
Shifting into low-range four-wheel drive is a little more involved than shifting into high-range four-wheel drive. Drivers will need to shift the transmission into neutral to disconnect torque to allow the transfer case to shift gears.
The P0836 code is a standard OBD-II trouble code that detects a problem with the four-wheel drive (4WD) switch circuit. The 4WD switch circuit actuates the four-wheel drive system, and is responsible for altering the transfer case gear ratios between four wheel high, four wheel low, two wheel high, and two wheel low.
A four-wheel drive actuator is a component of your 4WD system that automatically locks hubs. When you engage your 4WD, transfer case shifts to also drive the front wheels. Once installed, this device allows you to engage or disengage 4wd feature of your vehicle.
Four-Wheel Drive Disadvantages

It uses more fuel and can also lead to overconfidence, leading to more situations where you can get stuck. Save money and fuel by only using 4WD when you need it. The main disadvantage of 4WD is added cost for purchase, maintenance, and fuel.

Actuator failure – signs and symptoms

Complete loss of power, causing the vehicle to enter limp mode. Intermittent low pressure. Low boost. Overboost.

The system or actuator filter is blocked or clogged. The actuator ports are plugged with contaminants. The speed controls are closed. There is too much condensation.
The most common symptom of the A/C Actuator going bad or when the Blend Door is stuck is when you feel inconsistent air flow coming in. The desired air you want whether it be hot or cold, is being diverted incorrectly, so you are not getting a consistent temperature out of the A/C system.
Rattling is one sound you want to be aware of. If you hear odd rattling sounds when you accelerate, this might be a symptom of a bad torque converter. The same can be true of whirring noises.
The torque converter is a crucial component that connects the engine to the transmission and allows the car to shift gears. Without a torque converter, the engine would not be able to transfer power to the transmission and the car would not be able to move.
Overheated Transfer Case

The transfer case is what splits the power between the front and rear axles. If it overheats, it may no longer be able to operate according to spec, causing the 4WD light to flash. Sometimes, the flashing light signifies that the system itself has deactivated until it can cool down.

One of the most noticeable symptoms of torque converter shudder is vibrations or shaking while driving. These vibrations can be felt through the steering wheel, floorboard, or seat of the vehicle. The severity of the vibrations may vary depending on the extent of the shudder and the speed of the vehicle.
Overheated Transfer Case

The transfer case is what splits the power between the front and rear axles. If it overheats, it may no longer be able to operate according to spec, causing the 4WD light to flash. Sometimes, the flashing light signifies that the system itself has deactivated until it can cool down.

Like AWD systems, 4WD can send torque to all four wheels to maximize traction when needed. Unlike AWD systems that activate automatically, the driver typically must engage 4WD with the push of a button or a pull of a lever.
Like AWD systems, 4WD can send torque to all four wheels to maximize traction when needed. Unlike AWD systems that activate automatically, the driver typically must engage 4WD with the push of a button or a pull of a lever.
Don`t try to engage these 4 wheel drive systems when the vehicle is moving or you can damage expensive components. However, most 4WD systems can now be shifted into or out of 4WD on the fly at the push of a button. The most sophisticated 4WD systems are fully automatic.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

4wd engages but vehicle bucks like 4wd is slipping.
ANSWER : There is likely an internal issue going on within your transfer case. The most common cause of transfer case slippage is low fluid. I suggest that the transfer case fluid condition and level is checked. If the two wheel drive mode works just fine then it is more than likely there is a fault in the transfer case not the transmission itself. I also suggest that a technician check the shift linkage from the 4 wheel drive shifter to the transfer case. Make sure it is still in proper adjustment. Another way you could test the transfer case is by removing the shift linkage and moving the transfer case through the four-wheel-drive functions by hand. If they feel any trouble with it going into the separate gears then that helps further indicate that it is a transfer case issue. Usually a four-wheel drive fault will come with some type of indicator other dashboard and or a code stored live in the vehicle computer. A technician such as those we provide here can run a scan diagnosis on the transmission module of your vehicle to get some clues as to what the problem could be. I will ask customer service to send you an estimate for a four-wheel drive malfunction diagnosis.

Why won’t the starter motor engage and turn engine over. Also, the clutch pedal won’t move and the clutch is partly engaged but slips.
ANSWER : If the clutch pedal is not moving and the clutch is partially applied, then the clutch release bearing may be damaged and the fork is jammed into the clutch forcing it to slip.

For the no start condition on the starter, try tapping on the starter solenoid and see if the starter engages. If the starter does not engage, then remove the starter and see if it engages without the engine. If the starter does engage, then try to crank the engine over by hand and see if it turns. If the engine does not turn, then the bearings may be locked up or there could be an issue inside the engine. If the engine does move, then the starter needs to be replaced. For the brake lights not shutting off, the brake light switch could be applied as it may be not connected properly on the brake pedal. Check to see the location of the brake pedal light switch and adjust the location to relax the switch. If the switch is relaxed, then the brake light switch would need replaced.

I recommend seeking out a professional, such as one from Your Mechanic, to help you with the no start and clutch issue.

Truck isn’t engaging into 4 Hi, but will go into 4 Low.
ANSWER : Hi there. Sounds like the shifter module motor or shifter rail is not working properly. Check the wiring on the shifter module motor on the transfer case and see if the wires are split or damaged. If the wires are good and the harness has no corrosion or oil in it, then remove the shifter module motor and put it on a jack or something while it is hooked up under the vehicle. Jack up the vehicle and put the tires off the ground and put the vehicle on jack stands. Start the engine and put the vehicle in 4 Low and observe what the shifter module motor does. If the motor rotates and is working, then the issue lies within the transfer case. If the motor only turns a little and mostly turns on 4 HI, then I recommend replacing the shifter module motor to the transfer case. Also, the transfer case lock switch may also cause the transfer case to not engage into 4 HI as well. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose the transfer case before replacing any parts.

went from starting quick to running like crap and sound like crap also has a small back fire noise like say B with ur lips silnt
ANSWER : Hello there. If the fuel tank is contaminated with debris, it should be either replaced or completely cleaned out. However, the problem with older fuel cells is they are metal, and likely have a lot of rust in the fuel cell; which will contaminate the fuel and lead to the "running like crap" issues. It is also possible that you have an exhaust leak which can create the same type of sound and backfiring problems.

4wd not engaging but 4wd illumination is still turning on.
ANSWER : Hi there. The clicking noise that you are hearing from your transfer case area could the double cardan universal joint turning with a bad bearing. Check the front driveshaft for excessive play and see if one of the universal joints are damaged. If the driveshaft and universal joints are good, then the transfer case is making the sound. For the transfer case not engaging, the fork inside could be bent when the motor turns the fork in. The computer (ECM) will see if the motor works, but it cannot determine if something mechanical stops working. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your transfer case.

"Service 4WD" shows on the dash
ANSWER : Hi there. Check the harness wires from the transfer case to the output shaft speed sensor. See if the speed sensor wires are burned and shorted into the harness. This could cause the 4wd to engage when ever and at any speed. The wires could just be touching and not actually connecting until a bump hits them together. If the wiring is all good on the transmission and transfer case, then I suggest having the computer flashed (reprogrammed) to fix the 4wd issue. If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from YourMechanic, that can assist you with the 4×4 light.

My Suzuki Escudo engages gears when on 4WD mode but does not engage any gear on 2WD mode. What must be the problem?
ANSWER : Hi there. The synchronizer inside the transfer case has teeth that are ground down on the 2WD selection causing the transfer case not to engage into 2WD. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your transfer case issue.

Id like to purchase a car but i want to know how much it would cost to get the timing belt fixed on the vehicle.
ANSWER : Hello. Unfortunately if the timing belt brakes it is not usually as simple as just installing a new one on this vehicle. Most of the time when the timing belt brakes on this engine the pistons will contact the valves bending them. This would require that the cylinder heads be removed and the head rebuilt so this would be quite an expense. It really then depends on how cheap you are getting the vehicle for.