Shift Lock Control System: Diagnosis GMC Sierra III

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the automatic transmission shift lock control. Refer to «Checking Aftermarket Accessories»(ref-651023-S10146574172014081900000) .
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 in order to diagnose the symptom

Transmission Control Lever Malfunction

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the shift lock control solenoid.
2. Ignition OFF, test for less than 5.0 ohm between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Install a test lamp between the ground circuit terminal B and the control circuit terminal A.
4. Ignition ON, command the scan tool BCM Shift Lock Solenoid output control ON and OFF. The test lamp should turn ON and OFF as commanded. If the test lamp is always ON, test the control circuit for short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If the circuit tests normal, replace the transmission control.