Serv 4WD Light Jeep: Troubleshooting!

Serv 4WD light in Jeep will turn on for the following reasons

  • The front and rear axle is damaged
  • The wheel speed sensor is malfunctioning
  • The 4WD fuses are loose
  • The transfer case motor has become defective
  • The gear shifting is not happening properly
  • The 4WD system is malfunctioning

However, to solve this issue you need to replace some of the damaged parts. You can do it yourself or get the professionals to handle it. Make sure to troubleshoot the damaged part properly if you are trying to fix it yourself. You can also reset the Jeep.

Overall, the process can be quite straightforward. To get a detailed idea of how to fix them, let’s get started. 

Table of Contents

Serv 4WD Light Jeep: Reasons & Solutions

Serv 4WD Light Jeep

Your Jeep is not immune from codes and problems. There is both C123F due to a damaged steering column and C121C due to faulty ABS.  The table below shows some of the common reasons why your Jeep has the Serv 4WD Light on and solutions for them. 

Reason SolutionModels 
Problem with front and rear axleReplace damaged partsJeep Cherokee, Jeep Wrangler, Jeep Grand Cherokee, Jeep Commander, Jeep Renegade
Wheel Speed Sensor IssuesReplace Wheel Speed SensorJeep  Wrangler, Jeep Patriot, Jeep Compass
Loose FusesReset the FusesJeep Gladiator, Jeep Grand Cherokee, Jeep Wrangler
Faulty Transfer Case MotorReplace the Transfer Case MotorJeep Grand Cherokee, Jeep Liberty, Jeep Patriot
Incomplete Shift in GearsAvoid Shifting While in MotionJeep Gladiator, Jeep Cherokee, Jeep Renegade
Malfunctionality in 4WD SystemTake the car to the dealershipJeep Commander, Jeep Wrangler, Jeep Cherokee, Jeep Gladiator

As you can see from the table, different Jeep models have different reasons for the light to remain on. If you have a Jeep Grand Cherokee there are multiple reasons for the problem. 

Let’s dive into each of the reasons for Serv 4WD Light Jeep. 

Reason 1: Problem with Front And Rear Axle

The leading reason for flashing your car’s 4WD Service light is the differentials. A malfunctioning differential can cause the “Serv 4WD” light to light on. The differential or axles distribute power to the wheels. 

A defective front and rear axle can result in abnormal tire wear, noise, vibration, and steering and handling issues. Rear differential leaking is a common problem faced by drivers. So, You’ll hear a rattling kind of noise when you activate the 4WD system. 


You must look for any visible damage like wear and tear, loose connection, or other visible damage. If any parts of the axle are worn or damaged, they need to be replaced.

This can include things like CV joints, bearings, and seals. Properly inspect them and then get them replaced. You can check this video if you are looking to replace the front axle. 

However, keep in mind that the steps for replacing are a bit complicated, and if you are not sure then seek professional help. A single axle replacement can be somewhere between $300 and $1500 depending on the severity of the damage and local labor cost. 

Reason 2: Bad Wheel Sensor

The wheel sensor monitors the speed of the wheels and sends signals to the vehicle’s computer to ensure they’re rotating at the correct speed. They are an integrated part of your vehicle’s braking system.

But due to prolonged use, corrosion or any other internal defect the wheel sensors tend to malfunction. When that happens, the Serv 4WD Light turns on in the Jeep. 


First, make sure to troubleshoot Jeep JK front wheel sensor troubleshooting the Jeep wheel sensor properly. Check it and ensure that the sensor is the source of the problem. 

Once verified, get it replaced. You can replace the wheel speed sensor by yourself or get a professional to work on it. 

If you are not sure about the process or have never done DIY work before, then we suggest going for a professional. 

Reason 3: Loose Fuses

Having a loose or blown-out fuse is a significant reason for seeing serv 4WD light on the dash of your Jeep Cherokee, Jeep Gladiator, Jeep Grand Cherokee, and Jeep Wrangler. It is possible for the fuses to not make proper contact if they are loose, since they control the power supply to the 4WD system. 

Also, if the fuses are loose, they can cause an electrical short in the system, which can also trigger the service light.


Depending on the Jeep model, different fuse can be responsible for the Serv 4WD Light to turn on. If you are using a Jeep Grand Cherokee then the Final Drive Control Module (FDCM) or the Electronic Differential Lock (EDIFF) fuses are the main reasons for the problem. You should go to the fuse box and check the fuse labeled #25. 

In most cases, use the manual of your car to locate the fuses responsible for the four-wheel drive system of your car. Unplug and plug it in tightly to solve the issue. You need to replace the fuse if it’s blown Jeep Cherokee Service 4wd

Reason 4: Faulty Transfer Case Motor

Overheated or damaged transfer case motors are a common reason for the emergence of the warning light. It helps send power to the axles and also allows gear shifting. The transfer case housing is made of soft metal magnesium. 

The bearings and gaskets of the case are also prone to damage. Too much heat also destroys the internal components of the motor. 


Since it’s a vital component of your 4WD system, you need to solve this issue immediately. Repairing a broken motor is too complex, so replacement is the only solution. 

Head out to your local automotive technician and get the motor replaced. The average cost of this job for a Jeep Wrangler will be around $3800.

Reason 5: Incomplete Shift in Gears

An incomplete shift simply means switching 2WD to the 4WD transmission while driving. This is considered a bad practice and can also cause a “serv 4wd” light to appear.


It is always important to switch gears while the car is in a stale state, not in motion. This will prevent the warning light and also prevent further damage to your transmission system.

Reason 6: Malfunctionality in the 4WD System

If you find your Jeep Compass serv 4WD light on, it is an indication of failure of the electric system.  There are many wires and connections involved in the 4WD system. The service 4WD light can come on if the system malfunctions.

On the other hand, the actuator motor failure can cause the service 4WD light to come on since 4WD is engaged and disengaged by the actuator motor.


Take your vehicle to the nearest official dealership store. They will run some tests and acquire diagnostic error codes. 

These codes can pinpoint the actual problem with the 4WD system. So, the experts will troubleshoot according to these diagnoses.

How to Reset Jeep Serv 4WD Light?

If you face the flashing light from your 4WD, it’s a serious issue. The message will appear on the instrument cluster of your vehicle. The service 4WD light can be reset as a solution.

Step 1: Deactivate 4WD and Turn Off the Engine

First, deactivate the 4WD system before you shift to reverse by slowing the vehicle. Then, set 4 HIGH which is on the transfer case lever. Now put your Jeep in reverse and turn the transfer case to 2HIGH. At this point, you must turn off the engine of your Jeep.  

Step 2: Take Off the Fuse

After successfully turning off the engine, it is necessary to locate the fuse box. Usually, fuses are located inside the engine compartment. If you don’t find the fuse, you can find it by reviewing the manual. Now remove the fuse. 

Step 3: Replace the Fuse and Start the Engine

Now you need to replace the faulty fuse. You should wait for 10 seconds before reinstalling the fuse if it is fine.  Then, verify the engine by starting and engaging the vehicle. If the 4WD system still shows light, seek professional help.  

Frequently Asked Questions (FAQs):

Can I Drive with a 4WD Light On?

No, you can not drive with a 4WD light on. A 4WD light on signifies that the front or rear axle is damaged, the wheel speed sensor is not working properly or the 4WD fuse is loose. All of these can lead to other major issues. So it is best if you get your Jeep fixed as soon as possible. 

How to Tell if Your 4WD Has a Problem?

There may be no immediate indication that your vehicle’s 4WD is having problems. You can notice that the front tires are worn. Then, fuel consumption may increase if 4WD has a problem. Then, you can hear a rattling sound when you turn on the 4WD. To follow the appropriate diagnostic procedures, you can use the wiTech scan tool.

What Happens When You Drive 4WD Low?

You can drive with 4WD low, it provides benefits. It is particularly useful in slippery or off-road conditions when 4WD Low distributes power to all four wheels. Also, 4WD Low can increase the amount of torque available to the wheels, which can be helpful when climbing steep inclines or pulling heavy loads.


Hope this article helps you to understand and fix the serv 4WD light jeep and how to perfectly reset it.

Maintaining your vehicle regularly can prevent most of the issues responsible for service light showing. Your jeep’s performance requires routine check-ups, even if they are expensive. The service 4WD light can appear on your Jeep if you don’t maintain it.

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