Preliminary Inspection

CAUTION: Always turn ignition switch to OFF position before disconnecting or connecting any control module connector or battery. When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Before proceeding with TROUBLE SHOOTING, SYSTEM TESTS or SYMPTOM TESTS , the following precautions must be followed:

Vehicle must have a fully charged battery and functional charging system.
Always start at RETRIEVING DIAGNOSTIC TROUBLE CODES . Starting with any other test may result in incorrect results.
Only perform test steps indicated. It is not always necessary to perform all steps in a test.
Turn ignition switch to OFF position before disconnecting or connecting any module or component.
Use extreme care when connecting or disconnecting components during testing to prevent accidental grounding or shorting.
DO NOT use a test light in place of a DVOM, unless instructed otherwise.
Always disconnect scan tool after use or when disconnecting/charging battery.
Always perform appropriate VERIFICATION TEST after repairs are made. See VERIFICATION TESTS .