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Home >> Jeep >> 2011 >> Compass Limited, FWD, Automatic CVT >> Repair and Diagnosis >> Transmission >> Transmission Control Systems >> (Transmission Control Module (TCM) - Electrical Diagnostics) >> DTC Troubleshooting >> P0721-Output Speed Sensor Circuit Performance >> Theory of Operation
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Theory of Operation

The transmission system uses two speed sensors. One is used to measure input rpm (primary pulley) and one to measure output rpm (secondary pulley).

The Input Speed sensor detects the primary pulley rpm by the use of a three-wire magnetic pickup device that generates a square wave signal as rotation occurs and is monitored by the Transmission Control Module (TCM). These inputs are essential for proper transmission operation.