DTC P0718: Mainshaft Speed Sensor Intermittent Failure: General Description

The mainshaft speed sensor is attached to the outside of the transmission housing. The mainshaft speed sensor generates a pulsing signal according to the speed of the mainshaft idler gear on the mainshaft. Using that signal, the powertrain control module (PCM) determines the speed of the mainshaft. If no pulses occur with the mainshaft rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the fluctuation of the vehicle speed measured by the mainshaft speed sensor, a malfunction is detected and a DTC is stored.