Engine Controls - Basic Testing: Introduction

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

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions during 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.

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 the ENGINE PERFORMANCE section.

GENERAL MOTORS A & C CHART REFERENCE

System or Component

Diagnostic Information Location

A-1, Malfunction Indicator Light (MIL)

See DIAGNOSTIC CIRCUIT CHECK

A-2, Malfunction Indicator Light (MIL)

See DIAGNOSTIC CIRCUIT CHECK

A-3, No Start

See NO START - ENGINE CRANKS OKAY

A-5, Fuel Pump Relay

⁽¹⁾ See RELAYS, SOLENOIDS & MOTORS

A-7, Fuel System Diagnosis

See BASIC FUEL SYSTEM CHECKS

C-1, ECM/PCM Replacement Check

See ECM/PCM REPLACEMENT CHECK

C-1, MAP Sensor

⁽¹⁾ See ENGINE SENSORS & SWITCHES

C-1, Power Steering Pressure Switch

⁽¹⁾ See ENGINE SENSORS & SWITCHES

C-1, Park/Neutral Switch

⁽¹⁾ See ENGINE SENSORS & SWITCHES

C-2, Injector Balance Test

⁽¹⁾ See FUEL SYSTEM

C-2, Injector Leak Test

⁽¹⁾ See FUEL SYSTEM

C-2, IAC Motor

⁽¹⁾ See IDLE CONTROL SYSTEM in

C-2, ISC Motor

⁽¹⁾ See IDLE CONTROL SYSTEM in

C-3, Canister Purge System (Fuel Evap Control)

⁽¹⁾ See EMISSION SYSTEMS & SUB-SYSTEMS

C-4, EST Ignition Check

See BASIC IGNITION SYSTEM CHECKS

C-5, KS Ignition Check

⁽¹⁾ See IGNITION SYSTEM

C-6, Air Injection System

⁽¹⁾ See EMISSION SYSTEMS & SUB-SYSTEMS

C-7, EGR System

⁽¹⁾ See EMISSION SYSTEMS & SUB-SYSTEMS

C-8, M/T Shift Lights

⁽¹⁾⁽²⁾ See MISCELLANEOUS ECM CONTROLS

C-8, Torque Converter Clutch

⁽¹⁾ See MISCELLANEOUS ECM CONTROLS

C-10, A/C Clutch Control

⁽¹⁾⁽³⁾ See MISCELLANEOUS ECM CONTROLS

C-12, Electric Cooling Fan Control

⁽¹⁾⁽³⁾ See MISCELLANEOUS ECM CONTROLS

C-16, Engine Coolant Level Switch

See ENGINE SENSORS & SWITCHES

C-16, Fuel Pump/Oil Pressure Switch

See ENGINE SENSORS & SWITCHES

C-16, Oil Level Switch

See ENGINE SENSORS & SWITCHES

⁽¹⁾	Refer to SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section.

⁽²⁾	Covered in entirety in the TRANSMISSION SERVICE & REPAIR section.

⁽³⁾	Covered in entirety in the ENGINE COOLING section.

NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.