Service Precautions

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

• Ensure fuel pressure is released before removing fuel line or fittings, as fuel system is under pressure and may cause personal injury. See FUEL PRESSURE RELEASE .
• 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 jumper wire or circuit is fuse-protected.
• Before disconnecting connector from any control module, ensure ignition is off before removing connector.
• When checking voltage or continuity at any control module, probe connector for control module from pin side. DO NOT backprobe connector or probe wires through the insulation.
• DO NOT cause short circuits when performing electrical tests. This will set additional Diagnostic Trouble Codes (DTCs), making diagnosis of original problem more difficult.
• Use specified test equipment when performing electrical tests.
• When checking for spark, ensure coil wire is NOT more than 1/4" from engine ground. If coil wire is more than 1/4" from engine ground, damage to vehicle electronics and/or PCM may result.
• DO NOT prolong testing of fuel injectors or engine may hydrostatically lock.