Questions and Answers
Jumpy Speedometer
Q. Vince, Here's one for you. I have looked through similar Q&A in About, but I didn't see my exact problem. Here it is. I have a 1993 Honda Civic Coupe, 4 cyl, with about 105k miles on it. My problem is the speedometer sometimes works and sometimes doesn't! All other gauges work fine. It doesn't seem to care whether I am going fast or slow, downshifting or up, etc. It may seem to work better "cold" but that could be just a coincidence. It will read zero than jump to my speed for a while, than back to zero, etc. I do have cruise control, but I don't notice any difference. Any ideas?
Thanks so much for your time and I sure enjoy About!
BruceA. Your car has an electronic speed sensor. Instead of a speedometer cable, there is a sensor that fits into the speedometer mount on the transmission and is connected to the speedometer in the dash by wires where the signal is converted to a reading.
The problem could be in the sensor, wiring or the speedometer. One way to narrow this down is to turn the cruise control on and see if the cruise drops out while driving. If it does, then it's a good bet that the problem is in the wiring or the sensor itself. If it doesn't, then the problem is most likely in the speedometer.
The cruise control uses the signal from the speed sensor to set the speed and if it doesn't get that signal, the cruise stops working.
You can test the sensor with an analog (needle type) volt meter. Remove the sensor and connect the meter leads to the sensor connector and set it to the 5 volt range. Spin the sensor and the needle should jump twice for every turn of the sensor gear. If it does, then it's okay. Since the problem comes and goes, I would suspect the wiring or the speedometer is the most likely culprit.
