LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1998 >> Yukon 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Self-Diagnostic System >> Hard Or Intermittent Trouble Code Determination

Hard Or Intermittent Trouble Code Determination

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

During any diagnostic procedure, it must be determined if codes are hard failure codes or intermittent failure codes. Diagnostic tests will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows:

  1. Enter diagnostic mode. See RETRIEVING CODES . Read and record all stored trouble codes. Exit diagnostic mode and clear trouble codes. See CLEARING TROUBLE CODES .
  2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. MIL should go out. Run warm engine at specified curb idle for 2 minutes and note MIL.
  3. If MIL comes on, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. DTCs may require a road test to reset hard failure after clearing DTC. If MIL does not come on, all stored DTCs were intermittent failures.
scientia non olet · About LEMON Manuals