Questions and Answers

Honda Accord VSS Q. I have a 1994 Honda Accord LX/DX sedan, automatic transmission and I was wondering if the speed sensor has anything to do with the way the transmission shifts. And if it doesn't, what is its purpose? I would appreciate if you could help me with this problem. Thank you!

A. Let's see if this explains it for you.

PURPOSE:
The sensor is used by the Engine Control Module (ECM) to determine vehicle speed and by the speedometer to drive the trip odometer/mileage odometer stepper motors and the speedometer driver to indicate vehicle speed.

OPERATION:
The speed sensor pulses the signal wire, switching its connection to ground on and off. The number of pulses increasing with vehicle speed. This signal is used to operate the stepper motors for the trip/mileage odometer, and the speedometer driver to indicate vehicle speed. This same signal is used by the ECM to determine vehicle speed for PGM-FI operation.

The transmission itself has two speed sensors, a countershaft speed sensor and a main shaft speed sensor that monitors the actual speed of the transmission itself.

Here is a chart of all the inputs and outputs that should clear things up for you.