Used car

Pitfalls of buying a used car

In Auto Shop Talk by HomeTowne Auto Repair & Tire

This is just one of the experiences we’ve had working on a used car:

Our customer had just bought a 2013 Jeep Wrangler off a used car lot at a dealership. It had cool lights and just looked nice, beefy and fun to drive.

They brought it to us after they started hearing a growling noise when driving. After checking out the vehicle, the technician found out that it was the rear differential. After a couple of other checks, we decided it was time to replace it.

We went with a JASPER remanufactured unit. While we were taking the old rear differential apart and getting ready to install the new one, we learned that the axles had been changed to off road axles that had screw-in studs we needed to find. The old rear differential also had a gear ratio that was different from the Jeep’s original ratio and the front differential ratio.

The new rear differential came in and was installed. During the test drive, the transmission would go into limp mode — which basically means that it won’t shift gears.

We spoke to the customer about this issue and they told us, “Oh yeah, it happened to us a few times after we got it. We’ve only had it two weeks.” 

As we were doing more testing, we received codes for a speed sensor problem. Speed sensors are located inside the transmission on top of the valve body. Through other testing, we found the transmission control module was not communicating correctly.

A transmission control module came in and was programmed. We experienced the same problem while test driving, but now we had good communication.

To make a long story short, we also needed to replace the transmission and reprogram the PCM back to the correct programming. This time, when we took it for a test drive, everything worked great — just like it’s supposed to.

The differential having a much lower gear ratio in the back, driving in two wheel drive helped mask the problem. Once they started having problems and couldn’t resolve them, they most likely traded it in to give their problems to someone else.

So, if you’re wondering what the moral of the story is: When you’re buying a Jeep that has been fixed up, without an accurate history of its past, you should expect to run into some problems. Maybe not as extensive as this one, but with all the aftermarket parts (we’re not saying they’re bad parts), you may not know what has been installed on the Jeep correctly or incorrectly. 

It’s definitely a good idea to get it looked over very well by a mechanic at an auto repair shop. If it’s lifted or highly modified, you may also want to go to a second shop that specializes in Jeep performance and have those components looked at.

HomeTowne Auto Repair & Tire is an authorized Michelin and BFGoodrich tire dealer located in Woodbridge, Virginia. Automotive repair services are performed on all makes and models, including oil changes, brakes, alignments, inspections, and computer engine diagnostics.