In rare instances, some owners of
a 2004-09 GM passenger car or light duty truck equipped with gasoline engine
and manual transmission may comment that the Service Engine Soon (SES) light
has illuminated. Upon closer inspection using a Tech 2, DTC P0502 (vehicle
speed sensor circuit low voltage) may be found stored in the PCM.
Follow the appropriate diagnostic information in SI. If no cause for the DTC can be found, the condition may be customer induced. Supporting data may be found in the freeze frame info stored with the DTC.
For help in diagnosing the vehicle, review Tech 2 data parameters: Calculated Engine Load, Engine Speed, Output Shaft Speed Sensor and Clutch Pedal Position.
Inform the customer that excessive slipping of the clutch with the vehicle stationary or moving at low speeds may cause this DTC to set. This is considered normal vehicle operation. Engineering is currently investigating the concern and updated information will be released when it is available.
- Thanks to Jeff Gorenflo
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