Shift Interlock System: Diagnosis Chevrolet Silverado Classic 1500

Diagnostic Starting Point - Automatic Transmission Shift Lock Control

Begin the system diagnosis by reviewing the Automatic Transmission Shift Lock Control Description and Operation (with Allison Transmission) or Automatic Transmission Shift Lock Control Description and Operation (without Allison Transmission) . 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 Shift 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

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the automatic transmission shift lock control system. Refer to «Checking Aftermarket Accessories»(ref-277884-S30236091172008012100000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Shift Lever Does Not Move with Brake Pedal Depressed»(ref-277947-S07998810712008012100000)
2. «Shift Lever Can Be Moved without Brake Pedal Depressed (w/o Allison Transmission)»(ref-277947-S15087452312008012100000) or «Shift Lever Can Be Moved without Brake Pedal Depressed (with Allison Transmission)»(ref-277947-S20104949782008012100000)

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Testing

1. With the ignition ON, connect a test lamp between the A/T shift lock solenoid ground and supply voltage. Verify test lamp illuminates. If the test lamp does not turn ON, repair the ground circuit.
2. With the ignition ON, connect a test lamp between the A/T shift lock solenoid supply power and a good ground. Verify the test lamp does not illuminate. If the test lamp turns ON, replace the A/T shift lock solenoid.
3. Test the stop lamp switch for proper operation and supply power from the BCM. If testing indicates no supply power from the BCM, refer to Circuit/System Verification above.
4. If no trouble found in circuit, replace the BCM.