P071F Buick Transmission Mode Switch B Circuit High

P0720 Buick Output Speed Sensor Circuit Malfunction

Possible causes
– Faulty Revolution Sensor
– Revolution Sensor harness is open or shorted
– Revolution Sensor circuit poor electrical connection
Tech description
On most Infiniti vehicles, the vehicle speed sensor is called Revolution Sensor. If there are no mechanical problems in the transmission, usually replacing the revolution sensor takes care of the problem.
What about the obd code?
Diagnostic trouble code is detected when Transmission Control Module (TCM) does not receive the proper voltage signal from the sensor.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Speedometer improper reading
– Possible shifting problems
P0720 Buick Description

The speed sensor (revolution sensor) detects the revolution of the idler gear parking pawl lock gear and emits a pulse signal. The pulse signal is sent to the Transmission Control Module (TCM) which converts it into vehicle speed.

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