4x4 AnswerMan: Your Trucks & SUV Questions

May. 01, 2014 By Jaime Hernandez
Four-wheel drive Dodge Ram Truck crawling up Potato Salad Hill in Moab, UT. Itís lumpy and steep, with plenty of pucker factor.

Have a truck or SUV question for the 4x4 AnswerMan? Send your questions to editor@off-road.com. Please include your name and location, and be as detailed as possible about your questions.

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What's the difference between manual hubs and a selectable locking differential? My friend says I should get one but I'm unclear on the difference.

Jimmy Joe

Hi Jimmy Joe,

Manual hubs are found primarily on solid-axle trucks. They allow the inner axles to spin freely when 4-wheel drive is not in use. This causes less wear and tear on the drivetrain and can also improve MPG. Unfortunately, most late model trucks donít come with manual hubs. The good news is that some can be retrofitted with the help of companies like Dynatrac (http://www.dynatrac.com/). If youíre looking for factory manual hubs, youíll have better luck with pre-2000 models.

As for the selectable locking differential, this option is found mostly on specialized off-road vehicles like the Jeep Rubicon, Ford Raptor, Toyota TRD packages, and Dodge Power Wagon. A selectable locking differential (a.k.a. locker) uses a cable, electric actuator or air to engage the front or rear differential locker. The selectable locker in essence locks the left and right wheels on the axle so they both have power and turn at the same rate.  Having the ability to control this power from the driverís seat can really make a difference on the trail, giving your truck added traction and control when you need it most.

If the truck model you are looking at doesnít have selectable lockers as an option, you can always add them later.  Selectable differential lockers are available from companies like Eaton, ARB and OX.



4x4 AnswerMan,

I am looking for the same grille guard for a Ď96 Chevy and don't really understand the Warn website. What all do you have to buy to have the grille guard?


Letter sparked by Project Z71 on Off-Road.com

Hello Dyson,

The winch bull bar you like from Project Z71 is a Warn Trans4mer. Itís offered as a winch mounting system and can be purchased either as a grille guard or brush guard configuration. The one shown on Project Z71 combines both the Grille Guard and Brush Guard. The nice part about the Warn Trans4mer system is that you can securely mount a recovery winch using your factory bumper. The Warn Trans4mer is available for Chevy/GMC, Dodge, Ford, Jeep and Toyota.

You can find more information on the Warn Trans4mer here.





I'm so going to make mine this way! I was going to just use PVC pipe but this way looks so more pro.

Chris Potwin

Letter sparked by Breath Easy

Hi Chris,

Iím glad youíre taking the home-brewed approach. If youíve got the time to lay fiberglass and resin down, let the fumes blow. A custom snorkel like the one found on project Z71 fills a gap and makes for great DIY project.  For many U.S. domestic truck owners, there arenít any true off-the-shelf snorkels available.  Custom is the way to go.

Good luck!



4x4 AnswerMan,

My truck is running really rough. It shakes badly when I shift it into Drive or come to a stop. I thought the motor mounts were going bad, but then the check engine light came on. My friend has an OBD-II Scanner, so we pulled the code. It says that the truck engine is having random misfire P0300. Any ideas on how to fix this problem? It's a 2003 Chevy Colorado 4x4 pickup.


Hi Frank,

Sorry to hear your truck has the rock and rolls. The OBD-II code P0300 you found leads me to believe the problem is in the ignition system. The random misfire can be caused by something as simple as a bad spark plug, faulty wire, coil or distributor. Having a cylinder misfire will certainly make the engine get off rhythm, and it even cause the entire vehicle to shake, depending how bad it is missing.

If youíre lucky, you may be able to get even more information from the OBD-II scanner, pin pointing exactly which cylinder is causing the ruckus.  See if your friend can run another scan to get more information. If you need to isolate the problem yourself, the plan of attack is to start with the basics.

You need three main ingredients to make the engine run: fuel, spark and air. Start by pulling the spark plugs. If you notice anything unusual, like a wet plug or excessive erosion, youíre on to something. Here is a spark plug reference guide to help identify common problems

If your plugs have over 100K miles, they probably need to be replaced anyway.

There are a few different ways to test for spark. Since your truck is newer, each cylinder has its own coil. It does not use traditional spark plug wires, at least not like you would find in a distributor ignition system. Instead, it uses a Distributorless Ignition System (DIS). There is a wiring harness from the DIS module that goes to each ignition coil, so check the wiring for visible damage.

Using an in-line spark checker kit (like the one pictured below), you can check each coil for spark. If you come across an ignition coil with no spark, and happen to find a fuel wet spark plug, you may have found the problemóa bad coil. You can go a step further and check the ignition coil using a multimeter to see if itís within working specs.

Individual DIS coils can be tested by removing and disconnecting from the wiring harness. Set the ohm meter in the low range and connect the leads across the coil's primary terminals, compare the primary resistance reading to specs (usually less than 2 ohms). Then connect the ohm meter leads across the coilís secondary terminals and compare the secondary resistance reading to specs (somewhere in the 6,000-30,000 ohms range).  If readings are outside the specified range, the coil is defective and needs to be replaced.

In our experience, weíve isolated ignition problems to a single DIS coil.  Since each cylinder has an individual coil, and you can just replace the one giving you trouble and be on your way.



Hi 4x4 AnswerMan,

Where do you connect your single vacuum line up to an engine? I want to do the same to my truck. I understand the passenger side of actuator but where did you connect other side?

Jason Earle

Letter sparked by The Automatic Disconnecting Differential System

Hello Jason,

You should be able to bypass the switches and vacuum tank by running a direct vacuum line to the engine intake (see vacuum diagram below).  You may need to use a ďTĒ fitting to tap into an existing line.  Below are instructions on how to permanently lock the ADD unit (Off-Road Use Only. Not recommended for street/highway driving). 

PERMANANTLY LOCKING ADD UNIT: There are 2 hoses connected to the ADD actuator. The vacuum line on the passenger side of the actuator puts shaft into the diff and the other side removes it.  Remove the vacuum tank and vacuum switches. Then connect a single vacuum line to the passenger side of the actuator to keep it locked. Cap the driver side tube. This will prevent the ADD system from unlocking. The switches can be found behind the battery on the inside right fender, the vacuum tank is in front of the front right tire under the fender. Be sure to cap the vacuum feed from the engine to the switches or remove the "T" feeding it all together.



4x4 AnswerMan,

Am I better off purchasing a new truck with an "off-road" package or just upgrading it on my own?

Chuck Davis

Hi Chuck,

If you plan on using your truck off-road frequently, then the options available in an ďoff-road packageĒ can make it worth the extra coin. Many times these packages will include bells and whistles not available on the base 4x4 model, such as differential lockers, premium shock absorbers, all-terrain tires, skid plates and such. They are also tame enough for the pavement, which makes it nice if it will be a daily driver. On some models the markup for the off-road package may only be 10-15%, which is not bad considering everything youíre getting. 

The special trim and badges applied to the truck may also be a styling factor you may appreciate. Thereís also the instant gratification you get from driving off the showroom floor with a truck capable of tackling most off-road trails and terrain under the sun.

If youíre not impressed with the off-road package available, you might be better off just getting a 4x4 model you can build to suit your needs. There may not be any real incentive to getting the most expensive off-road package if youíre just going to strip it down to make room for more aggressive gear. Save some money and do it your way.

They are two very different animals. Only you know which one suits you best. In either case, you will still have a four-wheel drive, which will allow you to go places other vehicles will never see.

Happy truck shopping!



4x4 AnswerMan,

I have a 2004 Yamaha Blaster and canít get it to idle. What are the adjustments for the air and gas flow?                               


Hi Wanda,

If your Blaster is running rough and has been sitting for a while, I would highly recommend a carburetor tune-up. Buildup accumulates inside the carburetor if they sit around and will make tuning difficult. Here is a good article by our ATV expert Rick Sosebee that should help:

ATV Tech: Basic Carburetor Clean-up

Once youíve cleaned your carburetor, you can give next article a quick read to help you understand and adjust the idle.


While youíre at it, check the spark plug. If it looks super oily or worn, swap it with a new one. Doing these little maintenance items should give your Yamaha a better pulse.

If you have any more ATV questions, make sure to check out our ATV AnswerMan column.

Enjoy the ride!



Dear Off-Road.com,

I want to buy a Land Cruiser completely like this. Would you please help me?  Where can I find one?

Mahan Zehi

Letter sparked by Shop Build: Slee Off-Road Toyota 80 Series Land Cruiser 

Hello Mahan,

Youíre in luck. This amazingly clean Toyota 80 Series Land Cruiser recently went up for sale. It comes fully equipped for overland off-road adventure and complete history of all maintenance and upgrades done to it. They are asking $29,785 USD. You can get all the details at Slee Off-Roadís website.





This was quite enjoyable to read. I don't know that I'd ever take a
Rav4 of any generation on trails like those, but it's fun to live vicariously through someone who's just crazy enough to try it. The best part was reading your colorful take on the experience. It was amusing and brought a smile. Ride on little trucklet. Ride on.

Jonathan Scherer

Letter sparked by Rav4 Crawler Finding the Limits of the Trucklet 

Hello Jonathan,

Glad the Trucklet made you smile. It did bring joy to many, including those in disbelief on the side of the trail. It was amazing seeing firsthand what this little sport utility was able to handle.

Read more Trucklet stories and discover the antics that builder Justin Fort got away with in this little 4-wheel drive (keyword ďRAV4 TruckletĒ).



4x4 AnswerMan,

I have the 1993 SR5 3 liter V6. It's pushing 300k, one rebuild and two head gasket replacements later (plus a transmission rebuild). Still runs like itís new, pretty sure it's impossible to kill these vehicles.                                  

Chase Stoudt

Hi Chase,

Great to hear you have had such a great experience with your Toyota 4WD.  Weíve always had a Toyota and a domestic truck in our garage. Under 100k miles they seem to be about the same, but itís when you get over that 100k mark that the Toyota really starts to shine as far as reliability. Donít get me wrong, we still like tinkering with our Detroit trucks, but having a driver you can count on with minimal upkeep makes a Toyota a good choice to keep in your stable.

Have a truck or SUV question for the 4x4 AnswerMan? Send your questions to editor@off-road.com. Please include your name and location, and be as detailed as possible about your questions.

More 4x4 AnswerMan Columns
March 2014

February 2014

January 2014

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