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 SYSTEM 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 unless specifically directed to do so.
• 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.