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HOMESERVICE MANUALSGMC1984PICKUP K2500, 6.2 C, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMDIESEL CEC TESTINGDIESEL DIAGNOSTIC CHECK - TESTER CHECK
1984 GMC Pickup K2500, 6.2 C, Standard

Diesel Diagnostic Check - Tester Check

1984 GMC Pickup K2500, 6.2 C, StandardSECTION Diesel Diagnostic Check - Tester Check

This check determines if the ECM is capable of detecting a fault in the DEC system. Prior to any diagnostics, correct operation of the tester must be verified.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).
  1. This step checks to see if the tester is supplied with 12 volts. With power cord installed, light should glow.
  2. This step determines if the ALDL circuit is grounded or faulty. When the tester is connected to the ALDL connector, the "CHECK ENGINE" light (CEL) should remain on.
  3. When ignition is turned on, the CEL should remain on. If not, ECM may be shorted internally. The normal ECM reset time is 10 seconds. Therefore, when the tester is used during diagnostics, the CEL will flicker when function knob is rotated.
Fig 1: Diesel Diagnostic Check - Tester Check
G9485
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.