Engine Controls - Basic Testing: Introduction
The following diagnostic steps help prevent overlooking simple problems and begin diagnosis for no-start conditions.
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:
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 this Section.
GENERAL MOTORS A & C CHART REFERENCE
| SYSTEM OR COMPONENT | DIAGNOSTIC INFORMATION LOCATION | ||||
|---|---|---|---|---|---|
| DIAGNOSTIC CIRCUIT CHECK | See DIAGNOSTIC CIRCUIT CHECK in this article | ||||
| A-1 & A-2, SERVICE ENGINE SOON Light | See DIAGNOSTIC CIRCUIT CHECK in this article | ||||
| A-3, No-Start | See NO-START DIAGNOSIS in this article | ||||
| A-5, Fuel Pump Relay | See RELAYS, SOLENOIDS & MOTORS in SYSTEM/COMPONENT TESTS article in this section | ||||
| A-7, Fuel System Diagnosis | See BASIC FUEL SYSTEM CHECKS in this article | ||||
| C-1, MAP Sensor | See ENGINE SENSORS & SWITCHES in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-1, Power Steering Pressure Switch | See ENGINE SENSORS & SWITCHES in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-1, Park/Neutral Switch | See ENGINE SENSORS & SWITCHES in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-2, Injector Balance Test (4.3L) | See FUEL CONTROL in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-2, IAC Motor | See IDLE CONTROL SYSTEM in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-3, Canister Purge System | See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-4, EST Ignition Check | See BASIC IGNITION SYSTEM CHECKS in this article | ||||
| C-5, ESC Ignition Check | See IGNITION SYSTEM in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-6, Air Injection System | See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-7, EGR System | See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-8, Torque Converter Clutch | See MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-8, Manual Transmission Shift Lights | See MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-10, A/C Clutch Control | (1) See MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section | ||||
| C-12, Electric Cooling Fan Control | (2) See MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section | ||||
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