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Engine Controls - System/Component Tests: Introduction

Before testing separate components or systems, perform procedures in BASIC TESTING article in this section. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES - 4.3L 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 and refer to WIRING DIAGRAMS at the end of this article to isolate wiring harness shorts or opens.

The following table provides the location of commonly used diagnostic info. These former "A" and "C" charts are now written in text and inserted into the new Engine Performance workflow. To familiarize yourself with this Engine Performance section workflow, see AA - USING THIS SECTION (GENERAL INFORMATION) in this section.

GENERAL MOTORS "A" & "C" CHART REFERENCE

System or Component Diagnostic Information Location
DIAGNOSTIC CIRCUIT CHECK (1) See DIAGNOSTIC CKT CHECK
A-1 & A-2, Malfunction Indicator Light (MIL) (1) See DIAGNOSTIC CKT CHECK
A-3, No-Start (1) See NO-START DIAGNOSIS
A-5, Fuel Pump Relay See RELAYS, SOLENOIDS, MOTORS & MODULES 
A-6 & A-7, Fuel System Diagnosis (1) See BASIC FUEL SYSTEM CHECKS
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, IAC Valve See IDLE CONTROL SYSTEM 
C-3, Canister Purge System 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 See MISCELLANEOUS ECM CONTROLS 
C-8, M/T Shift Lights See MISCELLANEOUS ECM CONTROLS 
C-10, A/C Clutch Control See MISCELLANEOUS ECM CONTROLS 
C-12, Electric Cooling Fan Control (2) See MISCELLANEOUS ECM CONTROLS 
Injector Balance Test (PFI) See FUEL CONTROL 
(1) See appropriate F - BASIC TESTING article in this section.
(2) Covered in entirety in appropriate ENGINE COOLING article.
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