Service Precautions

Before proceeding with diagnosis, the following precautions must be followed:

• Always check if any Technical Service Bulletins (TSBs) apply to vehicle.
• ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT  allow fuel to contact engine or electrical components. See FUEL PRESSURE RELEASE .
• 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.
• Vehicle must have a fully charged battery and functional charging system.
• Probe PCM 60-pin connector from pin side. DO NOT  backprobe PCM connector.
• DO NOT  cause short circuits when performing electrical tests. This will set additional trouble codes, making diagnosis of original problem more difficult.
• DO NOT  use a test light instead of a voltmeter.
• When checking for spark, ensure coil wire is NO more than 1/4" from ground. If coil wire is more than 1/4" from ground, damage to vehicle electronics and/or PCM may result.
• DO NOT  prolong testing of fuel injectors, or engine may hydro-statically (liquid) lock.
• Always repair lowest trouble code number (MIL) or first trouble code message displayed (scan tool) first.
• Always perform verification procedure test after repairs are made.
• Always disconnect scan tool after use.
• Always disconnect scan tool before charging battery.