This Preliminary Information communication provides information to the technician about vehicles that seem to have a noise coming from the transmission assembly. Technician will need to inspect the fluid level to insure it is correct using Service Information document 3327666. Also the technician will need to check for Diagnostic Trouble Codes. Some Diagnostic Trouble Codes will cause the transmission to default to maximum line pressure that will cause a noise. If the fluid level is correct and there are no Diagnostic Trouble Codes found and the noise is coming from the inside the transmission, remove all three speed sensors for inspection. If an excessive amount of debris in found on any one of the speed sensors remove the transmission fluid pan. If there is excessive metal debris on the magnets the transmission will need to be replaced. Dealer will need to call General Motors Product Quality Center for further assistance.
