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Retrieving Codes (Non-Scan)

NOTE: The Assembly Line Data Link (ALDL) connector may also be referred to as the Data Link Connector (DLC) in flow charts. This is the same connector.
  1. Turn ignition on with engine off. Malfunction Indicator Light (MIL) should glow. Locate Data Link Connector (DLC), attached to control module wiring harness. Most DLCs are located under dash on driver's side of vehicle. For exact location of DLC, see appropriate COMPONENT LOCATIONS illustration in SYSTEM/COMPONENT TESTS - 5.7L article. Insert jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of DLC (terminals No. 5 and 6 of 16-terminal connector). See Fig 1. Turn ignition on.
    NOTE: Inserting jumper wire into test and ground terminals of DLC with engine running will cause fuel-injected vehicles to enter field service mode and codes will not flash. See FIELD SERVICE MODE in BASIC TESTING - 5.7L article.
  2. Malfunction Indicator Light (MIL) should flash codes. Each code is flashed 3 times. If codes DO NOT  flash, perform DIAGNOSTIC CIRCUIT CHECK (GASOLINE) in BASIC TESTING - 5.7L article. To exit diagnostic mode, turn ignition off and remove jumper wire from DLC.
Fig 1: 12-Pin DLC Connector Terminal ID
G90B01199Courtesy of GENERAL MOTORS CORP.
Fig 2: 16-Pin DLC Connector Terminal ID
G94J34081Courtesy of GENERAL MOTORS CORP.