GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P280A: Transmission Range (TR) Switch Circuit Not Learned

Circuit/System Description

This diagnostic addresses if the Gear Selector Neutral Position has not been learned.

Conditions for Running the DTC

Not in Service Mode

Conditions for Setting the DTC

Gear Selector Neutral Position has not been learned

Action Taken When the DTC Sets

    • DTC P280A is a Type A DTC
    • Disable engine start

Conditions for Clearing the DTC

DTC P280A is a Type A DTC

Diagnostic Aids

Improper shift cable adjustment may cause DTC P280A to set. Refer to the Shift Control Cable Adjustment procedure.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline Harness Connector End View
    •  Automatic Transmission Internal Connector End Views
    •  Automatic Transmission Related Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

    •  Diagnostic Trouble Code (DTC) Type Definitions
    •  Diagnostic Trouble Code (DTC) List/Type

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

  1. Ignition ON, observe the DTC information with a scan tool.
  2. Record Freeze Frame and Failure Records.
  3. Clear DTC’s.
  4. Operate the vehicle under the conditions observed in the Failure Records.
  5. Observe the DTC information with the scan tool. Verify that the DTC does not set.
If DTC P280A is set, perform the Transmission Adaptive Learn and Transmission Neutral Learn procedure.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.