Diagnostic Starting Point - A/T Shift Lock Control

Begin the system diagnosis by reviewing the system description and operation. Refer to Transmission Identification Information. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation.Refer to Symptoms-Automatic Transmission Sham Lock Control in order to identify the correct procedure for diagnosing the system and where the procedure is located. - Symptoms - Automatic Transmission Shift Lock Control
Refer to Transmission Scan Tool Data List. Use the scan tool data list under the following conditions:
^ The Powertrain On-Board Diagnostic (OBD) System Check is complete.
^ The on-board diagnostics are functioning properly.
^ No DTCs are present. Testing and Inspection

The values below represent a typical display recorded from a properly functioning system.

Important: Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts. Only the parameters listed are used for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis. Scan tool values below were recorded under the following conditions:
^ Engine at idle
^ Upper radiator hose hot
^ Closed throttle
^ Transmission in PARK
^ Closed Loop operation
^ Accessories OFF
^ Brake pedal not applied