Ground bad somewhere diagnosed Po 502 bad

Asked by Jan 28, 2017 at 01:59 AM about the 2002 GMC Sierra 1500 SLE 4WD Standard Cab LB

Question type: General

Diagnosed. Came up PO 502.
LIGHT ON FOR ABS BRAKES
PARKING BRAKE DUMMY LIGHT
CHECK ENGINE LIGHT TRANS
NOT SHIFTING CORRECTLY. DID
FRONT GROUND by bumper
ground near TRANS what do I do
next???

1 Answer

73,765

P0502 GMC - Vehicle Speed Sensor Circuit Low Input.... Possible causes; Faulty Vehicle Speed Sensor, Vehicle speed sensor harness or connectors is open or shorted, Vehicle speed sensor circuit poor electrical connection, Faulty Powertrain Control Module (PCM)......Description, The Vehicle Speed Sensor (VSS) assembly provides vehicle speed information to the Powertrain Control Module (PCM). The VSS assembly is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The PCM converts the pulsing voltage to vehicle speed. The PCM uses the vehicle speed signal to determine shift timing and torque converter clutch (TCC) scheduling. Vehicle Speed Sensor Location Example:

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