Engine Controls - Basic Testing - 6.5L Diesel: 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 AA - USING THIS SECTION (GENERAL HELP INFORMATION) article in GENERAL INFORMATION section.

GENERAL MOTORS "A" & "C" CHART REFERENCE

System or Component	Diagnostic Information Location
DIAGNOSTIC CIRCUIT CHECK	See DIAGNOSTIC CIRCUIT CHECK
A-1 & A-2, Malfunction Indicator Light (MIL)	See DIAGNOSTIC CIRCUIT CHECK
A-3, No-Start	See A-3, NO-START DIAGNOSIS
A-6 & A-7, Fuel System Diagnosis	See BASIC FUEL SYSTEM CHECKS