LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1990 >> Safari Van M L4-151 2.5L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Relays and Modules - Computers and Control Systems >> Engine Control Module >> Testing and Inspection >> Initial Inspection and Diagnostic Overview
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Initial Inspection and Diagnostic Overview


A technician may request the ECU to perform a function test by grounding ALDL terminal H to A once for 2 seconds. This will activate the motor and the valves. The ignition must be cycled after each attempt to prevent a false code from being set.