AfterMarketNews AfterMarketNews Auto Care Pro AutoCareCareerHub Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service Speedville

Port of Opportunity

I was recently at a big-box electronics store and I saw a variety of OBD-II devices that are designed to track drivers, diagnose check engine lights and even perform remote starting. As a gadget geek, I was drawn into slick packaging and promises of a...


Water Pump Cavitation: What Cavitation in Pumps Means

Why Cavitation in Pumps Occurs The tiny “bubbles” of water pump cavitation can kill the pump. While you will never actually see the tiny bubbles of cavitation in pumps, you can see the damage of cavitation that looks like metal eaten by termites. That...


State-of-Charge and Charging Systems Diagnostics on Late-Model GM Vehicles

What to Know About GM State-of-Charge and Charging Systems On 2007 and up GM vehicles, using conventional battery and charging systems tests can prove inconclusive. This is because of GM’s Electrical Power Management (EPM) system designed to monitor...


Complete Clutch Replacement: No Noise, No Comeback

Diagnosing clutch and manual transmission noise can be a difficult diagnosis. There is no way of attaching a scan tool or looking into the bellhousing while the clutch is under load. Clutch diagnostics requires logic and understanding of how the parts...


Power Steering Hoses: Inspection and Repair

What Causes Power Steering Hoses to Fail? The life of power steering hoses is not easy. Power steering hoses must endure some of the highest pressures and temperatures under the hood. Coupled with ozone, oil and solvents attacking the outer layers of...


Subaru Alignment Spec: 2005-2009 Legacy

Subaru Repair Tips: 2005-2009 Legacy Alignment  The fourth-generation Subaru Legacy was produced from 2005-2009. It was available as both a sedan and a wagon until 2008 when the wagon was dropped. The front suspension design uses a MacPherson strut....


Replace Valve Stems at the First Signs of Corrosion

Every OEM that uses metal valve stems for its TPMS sensors advises that if any corrosion is seen on the valve stem, it should be replaced. If the valve stem breaks due to corrosion, it will result in rapid deflation of the tire. The...


Honda Engine Shuts Off, But Power Mode Stays in 'On' or 'Accessory'

Models: Honda models with one-push start. Problem: When your customer shifts into Park and shuts off the engine, does the power mode stay in ON or ACCESSORY? The culprit could be a misadjusted shift cable. If it’s not adjusted correctly, it puts...


Detergents for Modern Vehicles

In the 1980s, fuel injectors were rapidly replacing carburetors. And, with more fuel-injected vehicles on the roads, it quickly became apparent that some gasoline formulations were not suited for injectors and leaner-burning engines. Most fuels either...


Are You Regularly Maintaining Your Equipment?

Technicians who are idling because the welder won’t feed wire, the hydraulic ram won’t pull chains, the booth heater won’t heat or the air compressor won’t compress enough air is a costly mistake, as labor time is the most expensive thing in any...


Celebrate 'Back To The Future' Day By Watching The Time Machine Get A 2015 Detail

    For many today is just another Wednesday, but for a lot of people it is more than just your average Wednesday, it is "Back to the Future" Day. It is a day that everyone who watched the cult classic trilogy Back to the Future recognizes...


Failed Honda PCMs And CAN System Diagnostics

In early 2014, Gary Goms received one of his most challenging e-mail requests from a shop foreman of a Honda dealership. This service manager had read a column he’d written on PCM diagnostics for ImportCar and was asking his opinion about why three...

Home ASE Test Prep 4WD/AWD Hub Service On Kia Sportage And Sorento Models

Print Print Email Email

In the past 15 years, Kia four-wheel-drive (4WD) and all-wheel drive (AWD) systems have evolved from vacuum hubs and manual shifting transfer cases to fully electronic systems that use magnetic clutches for push-button operation. While you may never have to replace the entire transfer case or transmission on the popular Sportage and Sorento SUVs, you will have to replace hubs, sensors and solenoids on your customers’ vehicles. In this article, we’ll start with the early systems on the 2000 Sportage.

The most common complaint you’ll encounter is no 4WD operation, which can usually be traced to problems with the vacuum-actuated front hubs. Kia requires that the driver shift the transfer case into four-wheel-drive, choosing either high- or low-range gearing. The driver must then flip a switch that opens a vacuum-control valve, sending vacuum to the locking front hubs and engaging them to the drive axles. If there’s a weak link in the system, it’s the hubs.

The hubs can cause a couple of problems. The first, and most common, is no engagement. Many times, these troubles can be traced to the vacuum supply, rather than a mechanical problem with the hubs themselves. The first step is to be sure you have vacuum at the hubs with 4WD engaged and the engine running. If not, work backward looking for the vacuum leak; a convenient test point is the “T” fitting by the master cylinder where the lines branch off to the left and right sides. This “T” is downstream of the control solenoid and vacuum storage tank, so if you have vacuum here, you should have it at the hubs.

Many times, the problem is as simple as broken or disconnected vacuum hoses leading to the hub. But, there have been reports of problems with the steel lines running to the wheels. Over the years, these lines can rust, restricting flow and, in the worst cases, causing leaks. There are updated parts available, and Kia has issued a TSB on the subject (see sidebar below), but line replacement can be a tedious task. Many techs report good success with alternate methods of repair, but you’ll have to make the choice as to what’s the best course of action for your situation.

Another problem you can run into with the hubs involves engagement when it’s not called for. Usually described as a noise, in this case the hubs are sticking, and the wheels are engaging and disengaging the drive, the axles and front differential while the transfer case is in the two-wheel-drive position. Many times, simply backing up the truck will take care of this problem, but often it’s an indication that the hubs should come apart to be cleaned and lubed.

Depending on the condition of the original units, replacement hubs may be in order. In the case of the Sportage, road grime that’s finding its way into the hub through the previously discussed vacuum system can cause this problem. If the 4WD isn’t used very often, the broken or disconnected vacuum lines could have been overlooked for quite a while.


Should you find yourself in the position where ­replacement hubs are required, or if the customer values reliability over convenience, consider changing over to the almost-bulletproof aftermarket manually ­operated hubs.

These units provide a low-cost alternative to the automatic units and, while they require the driver to lock the hubs when 4WD is anticipated or required, many customers find it an attractive alternative.

If you do go with the manual hubs, be sure to seal any of the vacuum fittings to prevent ­debris from getting into the hubs, and disconnect the supply solenoid to prevent a manifold leak when 4WD is­ ­selected. It’s also a good time to service the wheel bearings or, at the very least, make any bearing adjustment that’s ­required.

The rest of the 4WD system on these vehicles presents more service opportunities than ­diagnostic challenges. Be sure to ­figure on changing the fluid in both differentials as well as the transfer case when doing a major service on a Sportage. Of course, any work on the hubs will have you also checking the brakes.


Looking at the later-model 4WD Kias, we see them moving away from locking hubs that engage the 4WD, and moving toward systems that de-couple the 4WD differential from the primary drive.

After a short hiatus, the reinvented Sportage was back on the market in 2005. Kia made big changes, one of which was going with a lighter duty, crossover-type FWD platform ­vehicle that engages the rear wheels to provide AWD as needed with a driver-controlled, lock-up option.

By looking at various sensors, the control unit decides when torque will be delivered to the rear wheels and at what percentage. By looking at ­individual wheel speeds and throttle position, brake input and steering angle, the control module will send a command to the rear differential-mounted coupler, applying the appropriate pressure to the internal clutch pack for the given conditions.

While the coupler handles the varying load, the continuously engaged, transaxle-mounted transfer case does the job of keeping the driveshaft spinning.

If the conditions require 4WD operation, the driver can choose to lock into FWD, providing the maximum 50/50 split to both axles. Designed for low-speed operation, the control unit will begin to disable the lock at 18 mph, and, at 25 mph, the lock system is fully disabled. As speeds come down, the lock feature will re-engage. Being speed dependent, if there is a problem with the wheel speed sensors, the lock option is disabled.


When it comes to potential problems, most will be mechanical issues, noises or vibrations. Instead of two CV axles there are four, and you have to consider the driveshaft as the shakes and noises are diagnosed. The wheel bearings and hubs are no different than what we see on any 4WD or AWD vehicle. The only serviceable items in the coupler are the bearings.

If you’re faced with a blinking 4WD lamp on the dash, or a suspect a problem with the system, it will be difficult to go much further without a scan tool that has enhanced software that will give you ­access to codes and data. Even with the very good information on the free Kia service information site (, you would be hard-pressed to have a successful outcome without the tooling.

With the transfer case mounted to the transaxle, when it comes to maintenance on the system, it’s easy for an inexperienced tech to think they share lubrication. That is not the case with the Kia and it’s important that the fluid level in the transfer case be checked and replaced on the same interval as you recommend for the transaxle.


The Kia Sorento models up to 2009 offered both a part-time on-demand system, as well as an optional full-time AWD system. We’ll take a look at the part-time system that Kia refers to as “Electronic Shift Transfer (EST),” that uses an electrically controlled transfer case as well as an air pump system to engage the front axle. This allows for shifting “on the fly,” from 2WD to 4WD, applying a fixed amount of torque. When in 2WD, the front “free running differential” is decoupled from the driveshaft, eliminating any noise or vibration while also eliminating the need for locking hubs.

When the 4WD switch is selected, an electric air pump is commanded on to pressurize the coupler, engaging the front differential pinion to the driveshaft, while the transfer case-mounted motor moves the shift forks. Then, finally, the magnetic clutch closes, providing torque to the front driveshaft. This is all controlled and monitored by the transfer case control module (TCCM). With either system, the ­vehicle has to be stopped to engage 4WD low range.

Like the Sportage, if the TCCM sees a problem, the 4WD lamp will flash. No tool is required to retrieve codes with the EST system. When no codes are present, turning the key on should result in the 4WD lamp lighting for 0.6 seconds as a bulb check, and then it will turn off.  If codes are present, the bulb check will be followed by a flash code in three seconds. There are seven codes available using ones and zeros. A short 0.5-second flash represents a zero, while a one-second flash indicates a one. The code will repeat itself three times; for example two shorts and one long flash is 001 (see flash diagram above).

There have been some problems with both the transfer case motor and air pump used for the differential coupler. That’s not too surprising, considering that the system spends most of the time in two-wheel operation. Sometimes, a simple tap on the transfer case shift motor or air pump will shorten the diagnostic process. Of course, a motor that comes back to life with a tap is certainly suspect and should be replaced, but that’s between you and the customer.

If you do find yourself diagnosing the front differential coupler, keep in mind that it operates on 5-8 psi, so don’t just put the shop air to it. When it comes to maintenance, the transfer case fluid is critical to long bearing and clutch life, so much so that transfer case oil pumps are used to keep it moving; be sure it’s checked and changed with the recommended fluid.

On all 4WD or AWD systems, tire size conformity is critical. The first diagnostic step for any problem should be to measure tire circumference. While the method doesn’t matter (we measure circumference with a narrow tape), just be sure they are the same size. Ideally, they will all be within 1/16”. Much more than that should bring up the discussion of tire replacement, especially if the problem involves binding or engagement issues in an on-demand system that appears to operate as expected.

On automatic or AWD systems, tire size is even more critical as the system sees the speed differential of the tire size as slippage and adjusts accordingly. It’s easy to see how this would shorten the life of the clutches. This is why it’s so important that tires be replaced only in sets of four.


<!–[if gte mso 9]>

The following two tabs change content below.

Bob Dowie

Bob Dowie has been in the automotive service business for 43 years, and his shop, Village Auto Works in Chester, NY, specializes in Honda, Toyota, Mazda and Nissan repair. Dowie owns and runs a Honda Civic and Nissan Sentra SER in SCCA GT Lite Class racing, and gets his technicians ­involved in various aspects of the sport.
Latest articles from our other sites:

The Right Way To Measure Customer Satisfaction In Your Auto Repair Shop

Far too many shop owners don’t measure Customer Satisfaction in their auto repair shops. It’s not that they’re not interested in the results, it’s just that they’re not exactly sure how to do...More

Gates Corp. And The National Institute For Automotive Service Excellence (ASE) Name Scott Miller 2015 Technician Of The Year

The automotive aftermarket division of Gates Corp., in collaboration with the National Institute for Automotive Service (ASE), has announced that Scott Miller of Osceola, Wisconsin, is the 2015 Gates/ASE...More

Should Your Shop Be Open Christmas Eve?

This year Christmas is on a Friday, and Christmas Eve is historically not a big sales day for most, so shop owners have the opportunity to offer their staff a 4-day Christmas weekend if they close on Christmas...More

Check Out The November Issue Of Brake & Front End Magazine

The digital version of the November issue of Brake & Front End magazine is available online. CLICK HERE to access the easy-to-view digital version that features articles on Power Steering Hose Inspection,...More

New VDO Fan Assembly Coverage Offered For Mini Cooper, Toyota Rav4 And Mazda Miata

Continental Commercial Vehicles & Aftermarket has expanded its world-class VDO Fan Assemblies program with 11 new engine cooling fan assemblies for late model import vehicles. The added coverage delivered...More

Replace Valve Stems at the First Signs of Corrosion

Every OEM that uses metal valve stems for its TPMS sensors advises that if any corrosion is seen on the valve stem, it should be replaced. If the valve stem breaks due to corrosion, it will...More

JohnDow Dynamic TPMS Introduces Six Training Video Modules

JohnDow Industries’ Dynamic TPMS, in an effort to enhance its existing TPMS training program, recently introduced six training video modules. “One of the major elements for TPMS success is proper...More

IPA's Cleaners Eliminate Corrosion On Large Male Electrical Pins

Innovative Products of America (IPA's) #8076 Carbide Tube Pin Cleaners allow for quick and safe removal of corrosion from large male electrical contact pins. The #8076 pin cleaners include 10 different...More