Recently while driving on the interstate my speedometer in my 99 Mercury Cougar dropped to zero and my transmission immediately down- shifted. At first I had no idea what happened, but after hooking-up a generic code reader to my car I received the P0500 error code telling me that my vehicle speed sensor had malfunctioned. I went to a local shop and paid ~$100 to have them put in a new speed sensor. At first it appeared to work perfectly and I thought my problem was solved, but later on that day my speedometer once again dropped to zero and my transmission had trouble shifting from 1st to 2nd and would never go into 4th gear. After this happened, I thought that there was something in my transmission that was actually breaking my speed sensor and that would be where I needed to start looking. A few days ago, however, my speedometer miraculously started working again and my transmission would shift. This went on for almost an entire day and I thought that my car was magically fixed...this was not the case. Currently, my speedometer will work about 1/4 of the time and when it is not working, my car will not shift correctly. Even when my speedometer is working somewhat, when I am not accelerating my speedo will drop to zero and my car will downshift...I really have no idea what is going on. So here is my question: What else could cause my speedometer not to work and my car to have trouble shifting if I just replaced my vehicle speed sensor (output transmission sensor)? Should I have the wiring checked, or is there something else that could be causing this. Please help as I am tired of driving in first gear and getting terrible gas mileage...and I'm sure my transmission cannot take it much longer. Thanks for the help.
- posted
16 years ago