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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 47 (Engine Controls - Tests W/Codes - 5.9L Diesel) >> Self-Diagnostic System >> Entering On-Board Diagnostics >> Malfunction Indicator Light (MIL) Diagnostic Mode

Malfunction Indicator Light (MIL) Diagnostic Mode

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine (if possible). On models equipped with A/T, move transmission shift lever through all gear positions, ending in Park. On all models, turn A/C on, then off (if equipped).
  2. Turn engine off. Without starting engine again, turn ignition on, off, on, off, and on. Record 2-digit DTCs as displayed by flashing MIL.
  3. For example, Code 23 is displayed as flash, flash, 4-second pause, flash, flash, flash. After a slightly longer pause, other codes stored are displayed in numerical order.
  4. Once MIL begins to flash DTCs, it cannot be stopped. If count is lost, start over. Code 55 indicates end of DTC display.
    NOTE: When using diagnostic tests, DO NOT skip any steps in test procedure, or incorrect diagnosis may result.
  5. Refer to DTCS/MESSAGES to translate DTC number to a system fault description (display on scan tool). Once DTC description is obtained, refer to TEST TC-1A and proceed to appropriate test. Test procedure may vary depending whether DTC is a hard or intermittent failure.
NOTE: While using DRB scan tool, if an error is made or technician is unaware of correct procedures, enter "F1" (Help) or HOW TO USE DRB from various menus. While using generic scan tool, refer to manufacturer's instructions.
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