Engine Controls - Basic Testing - Gasoline: Introduction

The following diagnostic steps help prevent overlooking simple problems. This is also where to begin diagnosis for no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint by test driving vehicle under the conditions in which the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

NOTE: Unless otherwise instructed in test procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.

NOTE: Following table provides location of commonly used diagnostic information. These former "A" and "C" charts are now written in text and inserted into appropriate location of engine performance workflow. To learn about engine performance workflow, see the AA - USING THIS SECTION (GENERAL HELP INFORMATION) article in GENERAL INFORMATION 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-6, Fuel System Diagnosis

⁽¹⁾ See BASIC FUEL SYSTEM CHECKS

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 in

C-2, ISC Motor

See IDLE CONTROL SYSTEM in

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, ⁽²⁾ A/C Clutch Control

See MISCELLANEOUS ECM CONTROLS

C-12, ⁽²⁾ Electric Cooling Fan Control

See MISCELLANEOUS ECM CONTROLS

⁽¹⁾	See I - SYSTEM/COMPONENT TESTS - GASOLINE article in this section.

⁽²⁾	Complete coverage in appropriate ENGINE COOLING article in the ENGINE COOLING section.