Service Precautions

CAUTION: Electronic modules are sensitive to static electrical charges. Proper grounding of technician and workplace is essential to prevent damage.

CAUTION: When using scan tool, exit all scan tool tests before cycling ignition switch from OFF to RUN position unless scan tool instructions indicate otherwise. Follow all scan tool manufacturer's instructions, or diagnostic trouble codes (actual or false) may set, vehicle systems may malfunction or scan tool may malfunction.

Unless otherwise specified, make all voltage and resistance measurements with a Digital Volt-Ohmmeter (DVOM) having an input impedance of 10 megohms or greater. Use adapter from Terminal Test Adapter Kit (J-35616-A) connected to DVOM when making all measurements.
Do not replace Body Control Module (BCM) unless a DTC remains current after all DTC repairs have been performed. Do not replace BCM if only history DTCs are set. Always check module ground and power circuits prior to replacing a control module. See DATA LINK CONNECTORS, GROUND DISTRIBUTION and/or POWER DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
Diagnostic Trouble Code (DTC) tests are written specifically for use with GM Tech 2 scan tool. Generic scan tool can be used but may have limited functions. This article only covers portion of those systems and DTC tests which relate to anti-theft system diagnosis.