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Home >> Chevrolet >> 1994 >> Forward Control 4.3 Z, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 6.5L Diesel >> Self-Diagnostic System >> Entering Or Exiting Diagnostic Mode
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Entering Or Exiting Diagnostic Mode

  1. With ignition on and engine off, connect a jumper wire between Data Link Connector (DLC) terminal "B" (diagnostic terminal) and terminal "A" (ground). See Fig 1. The Diesel Electronic Control (DEC) system will enter diagnostic mode.
  2. In this mode, PCM will display DTC 12 by flashing the MIL once, followed by a short pause, then 2 flashes in quick succession.
  3. DTC 12 will be displayed 3 times. If no other codes are stored, DTC 12 will continue to flash until diagnostic terminal is ungrounded. To exit diagnostic mode, turn ignition off and remove jumper from DLC.
Fig 1: DLC Terminal ID
G120880Courtesy of GENERAL MOTORS CORP.
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