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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 208 (Automatic Transmission - ALLISON - Diagnosis) >> Self-Diagnostic System >> Diagnostic System Check >> Test Description

Test Description

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers listed below refer to step numbers in the diagnostic procedure:

  1. 1  - This step determines if the scan tool is receiving power through the DLC connector.
  2. 2  - The MIL should illuminate whenever the ignition is on and the engine is not running.
  3. 3  - This step determines if the TCM is transmitting class 2 serial data to the DLC and that the class 2 data circuit is not open or shorted.
  4. 4  - This step determines if a DTC is current or stored in history.

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