Section 1 (Engine Controls - Tests W/Codes - Diesel): Introduction
WARNING: This page does not describe the selected car, but rather 22 other vehicles, including the 1991 GMC Vandura Special, 1991 GMC Vandura, 1991 GMC Value Van, 1991 GMC Suburban, and 1991 GMC Rally Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
The Diesel Electronic Control (DEC) system, on 6.2L with light duty emissions, electronically controls EGR system operation, Torque Converter Clutch (TCC) engagement, cold advance and glow plug operation.
Most engine control problems are NOT computer related, but result from mechanical breakdowns, poor electrical connections, or damaged vacuum hoses. Before condemning the computer system, carefully perform visual and mechanical inspections. Failure to perform these inspections can result in lost diagnostic time.