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Home >> GMC >> 1998 >> Forward Control 6.5 F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - Introduction >> Self-Diagnostic System >> Special Tools (Diagnostic)

Special Tools (Diagnostic)

NOTE: For scan data values, refer to scan tool manufacturer owner's manual or compare values with a known-good component or vehicle.
NOTE: A scan tool connected to DLC is used to read DTCs and check voltages in system on serial data line. A scan tool is required to retrieve vehicle information.

Computerized engine control system is most easily diagnosed using scan tool; however, other tools may aid in diagnosing problems. These tools are a tachometer, test light, ohmmeter, digital voltmeter with a 10-megohm input impedance (minimum), vacuum pump, vacuum gauge, fuel injector test light, and jumper wires with appropriate terminal ends and length. A test light, rather than a voltmeter, must be used when indicated by a diagnostic test. In addition, special jumper harnesses or testers may be required by manufacturer to facilitate diagnosis.