After nearly five years of trusty service, my 1999 Ford Taurus began to experience a problem in the spring of 2004.  The speedometer would be accurate up to about 25 mph, but they would bounce wildly between 25 mph and 85 mph, regardless of the actual speed being driven.

At first, this was an infrequent problem, and then became gradually more common.  Of course, the problem never occurred when I took the car into the shop.  One of the mechanics apologized for his inability to troubleshoot the problem.  My response was that I worked in information technology and could fully understand the problem of a machine not reproducing a problem when you wanted it to (computers are notorious for this).

Some online research strongly suggested that the problem was with the vehicle speed sensor – an opinion that was backed up by some car experts in my office.  I had an extended warranty on the car, so the necessary repairs would be paid for, minus a small deductible.

The only problem was that the warranty company wouldn’t pay for a repair without the shop getting a reading from the onboard computer.  This made sense to me – they didn’t want to keep replacing parts until the shop fixed the problem by trial and error.  I continued to experience the problem – except for the times when I took it into the shop.  One time, the problem occurred for an entire weekend, only to cease on Monday when I took it in.

It was during this time that I learned that you really don’t need a speedometer.  You can gauge your rough speed by looking at the tachometer (engine RPMs).  This does vary a bit on hills, but you can make a rough estimate of your speed.  So I was able to drive the car without getting any speeding tickets, which was a small victory.  However, I was unable to use cruise control, which really sucked.

Finally, one weekend, the problem took a turn for the worse.  Not only was the speedometer not properly registering speeds above 25 mph, but the car was actually not moving any faster than 25.  There were some long drives that weekend.

At around 6:00 AM on Monday, I took a long drive down to the Ford dealer.  It was still early enough that the well-traveled road to the deal didn’t have many cars on it yet.  That’s exactly why I choose this time of day, of course – to minimize the risk of an accident.  The dealership opened at 8, so I pulled out a book and read for 90 minutes.

The dealership was able to get the Taurus looked at right away – and the computer was still throwing an error code.  Imagine my “surprise” when it indicated that the vehicle speed sensor was faulty.  A few minutes later, I was back on the road with a fully functioning speedometer.