Service Precautions

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

• Always wear safety glasses for eye protection.
• Ensure ignition switch is in OFF position unless test procedure requires it to be on.
• Fuel system is under constant fuel pressure. 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  .
• DO NOT  wear rings, watches, loose hanging jewelry or loose clothing. Keep away from moving engine parts, fan and drive belts.
• 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 DTCs, making diagnosis of original problem more difficult.
• DO NOT  use a test light instead of a voltmeter.
• When checking for spark, hold coil wire using insulated pliers. Position coil wire approximately 1/2" from ground. If coil wire is more than 1/2" from ground, damage to vehicle electronics and/or PCM may result.
• DO NOT  prolong testing of fuel injectors or engine may hydrostatically (liquid) lock.
• Always repair lowest DTC number or first fault displayed (scan tool) first.
• Always perform VERIFICATION TEST after repairs are made.
• Always disconnect scan tool after use.
• Always disconnect scan tool before charging battery.