1994 Buick LeSabre CustomFACTORY OEM SERVICE PROCEDURE

Engine Controls - System/Component Tests: Introduction

Before testing separate components or systems, perform all procedures listed in BASIC TESTING article in this section. Since many computer-controlled and monitored components will set a diagnostic trouble code if they malfunction, it is also recommended that self-diagnosis be performed. See appropriate TESTS W/CODES article in this section.

NOTE: Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens. The following table provides the location of commonly used diagnostic information. These former "A" and "C" charts are now written in text and inserted into the appropriate location in the new Engine Performance workflow. To familiarize yourself with the Engine Performance workflow, see AA - USING THIS SECTION (GENERAL HELP INFORMATION) article in in this section.
A & C CHART REFERENCE

System or Component Diagnostic Information Location
A-1 & A-2, Malfunction Indicator Light (MIL) (1) See DIAGNOSTIC CIRCUIT CHECK
A-3, No Start (1) See NO START - ENGINE CRANKS OKAY
A-5, Fuel Pump Relay See RELAYS, SOLENOIDS & MOTORS
A-7, Fuel System Diagnosis (1) See BASIC FUEL SYSTEM CHECKS
C-1, ECM/PCM Replacement Check See ECM/PCM REPLACEMENT CHECK
C-1, MAP Sensor See ENGINE SENSORS & SWITCHES
C-1, Power Steering Pressure Switch See ENGINE SENSORS & SWITCHES
C-1, Park/Neutral Switch See ENGINE SENSORS & SWITCHES
C-2, Injector Balance Test See FUEL SYSTEM
C-2, IAC Motor See IDLE CONTROL SYSTEM
C-2, ISC Motor See IDLE CONTROL SYSTEM
C-3, Canister Purge System (Fuel Evaporation Control) See EMISSION SYSTEMS & SUB-SYSTEMS
C-4, EST Ignition Check (1) See BASIC IGNITION SYSTEM CHECKS
C-5, ESC Ignition Check See IGNITION SYSTEM
C-6, Air Injection System See EMISSION SYSTEMS & SUB-SYSTEMS
C-7, EGR System See EMISSION SYSTEMS & SUB-SYSTEMS
C-8, Torque Converter Clutch (Trans.) See MISCELLANEOUS ECM CONTROLS
C-8, M/T Shift Lights (Trans.) See MISCELLANEOUS ECM CONTROLS
C-10, A/C Clutch Control (2) See MISCELLANEOUS ECM CONTROLS
C-12, Electric Cooling Fan Control (2) See MISCELLANEOUS ECM CONTROLS
C-18, Supercharger Boost Control See AIR INDUCTION SYSTEMS
(1) See BASIC TESTING article in this section
(2) Covered in entirety in the ENGINE COOLING section.
Factory Service Tools

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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.

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