Home Auto Repair

Last week I got an emergency call from my 17-year-old son. I was in the middle of something very important and so at the next available moment, I stepped out and gave my son a call. He told me that the horn on the family Jeep had just started beeping. He first assumed it was related to the car alarm. He went out and unlocked the car but the horn kept making noise. He then tried to start the car only to have it run roughly and not stop the racket. My son is a smart kid and so his next trick was to turn the car off and disconnect the battery. The horn stopped but it also meant the car was unusable until we could fix it.

The family Jeep is a 1998 Jeep Cherokee. If you are a Jeep fan, it is better known as an XJ. My wife and son only paid a couple thousand dollars for the vehicle but it came with a 3-inch lift kit and a sweet set of tires. It makes a great car for the kids even though it has a tendency to break down on a regular basis. Having it break down is part of what makes it a good car. I use it as a teaching tool for basic automotive mechanics with my kids. The XJ is incredibly easy to work on and tons of them are still on the road, making replacement parts extremely inexpensive.

Unfortunately automobile electrical problems are sometimes the most difficult to track down and fix. When my son turned on the car, the check engine light came on. I plugged in my OBD-II computer that I picked up many years ago and saw that the car thought it had a bad throttle position sensor (TPS) based on the P0123 code it was throwing. I then did a careful Internet search using the following, "1998 Jeep XJ P0123." Why did I use the term XJ instead of Cherokee? Jeep also makes the Grand Cherokee, which is a completely different SUV. Besides anyone that knows how to work on Jeeps calls them by the car's 2 letter code instead of model name.

The Internet search yielded a number of stories about people replacing the TPS only to have the problem still exist. Most had better luck replacing the clock spring which is part of the cruise control, horn, and TPS electrical circuit. Thinking about how the horn started going off while the car was just sitting in the driveway and the TPS is only engaged while the car is running, I decided to look for a quick check to verify it was the clock spring. Pulling off the steering-wheel shroud and unplugging one of the connections to the clock spring (it is located just above the turn-signal lever) fixed the P0123 code. The horn and cruise control no longer work, but the rest of the car does.

Now that I knew the real problem, I went back to the Internet and ordered a new clock spring for the Jeep. This is not one of those parts that auto stores keep in stock. Until then my son can drive the car to school and back with the help of an inexpensive air horn resting in one of the cup holders.