Pretest Inspection

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

• Always check if any TECHNICAL SERVICE BULLETINS apply to vehicle.
• Use caution whenever removing a fuel line or fitting. Fuel is under pressure and may cause personal injury.
• When using SELF-DIAGNOSTIC TESTS  for diagnosis, DO NOT  skip any steps, or incorrect diagnosis may result. Always perform indicated verification procedure after repairs are made.
• When using a jumper wire, ensure either the jumper wire or circuit is fuse-protected.
• Vehicle must have a fully charged battery and functional charging system.
• Probe ECU connector from pin side. DO NOT  backprobe ECU connector.
• DO NOT  cause short circuits when performing electrical tests. This will set additional fault codes, making diagnosis of original problem more difficult.
• DO NOT  use a test light in place of a voltmeter.
• When checking for spark, ensure coil wire is NOT more than 1/4" from ground. If coil wire is more than 1/4" from ground, damage to vehicle electronics and/or ECU may result.
• DO NOT  prolong testing of fuel injectors, or engine may hydrostatically (liquid) lock.
• When vehicle has multiple fault codes, always repair lowest number fault code (using voltmeter) or first fault displayed (using DRB) first.
• Always disconnect DRB after use.
• Always disconnect DRB before charging battery.