Service Precautions

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

• Before performing any testing procedures, check for any related Technical Service Bulletins (TSBs).
• Ensure fuel pressure is released before removing fuel line or fittings, as fuel system is under pressure and may cause personal injury.
• When using DIAGNOSTIC TESTS for diagnosis, DO NOT skip any steps, or incorrect diagnosis may result. When instructed to disconnect any connector, check that the connector is clean and in good condition after disconnecting connector. Repair or clean connector if necessary. Always perform indicated verification test after repairs are made.
• When using a jumper wire, ensure either jumper wire or circuit is fuse-protected.
• Before disconnecting any control module harness connector, ensure ignition is off before removing connector.
• DO NOT use 12-volt test light when checking 5-volt or 8-volt supply circuit, CCD bus circuit, PSI bus circuit, camshaft position sensor signal circuit, crankshaft position sensor signal circuit, oxygen sensor signal circuit or vehicle speed sensor signal circuit or Powertrain Control Module (PCM) may be damaged.
• When checking voltage or continuity at any control module, probe control module harness connector from pin side. DO NOT backprobe harness connector unless instructed to in test procedure. DO NOT probe wires through the insulation.
• DO NOT cause short circuits when performing electrical tests. This will set additional Diagnostic Trouble Codes (DTC), making diagnosis of original problem more difficult.
• Use specified test equipment when performing electrical tests.
• When checking for spark, ensure no fuel leaks exist and spark plug wire is NOT more than 1/4" from engine ground. If spark plug wire is more than 1/4" from engine ground, damage to vehicle electronics and/or Powertrain Control Module (PCM) may result.
• DO NOT prolong testing of fuel injectors or engine may hydrostatically lock.
• When replacing Transmission Control Module (TCM), pinion factor and shift quality quick learn procedure should be performed. See PINION FACTOR PROCEDURE and TRANSAXLE SHIFT QUALITY QUICK LEARN PROCEDURE in COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.
• If Powertrain Control Module (PCM) is replace, the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Supplemental Restraint System (SRS) module. See POWERTRAIN CONTROL MODULE  under PROGRAMMING.
• On models equipped with a Sentry Key Immobilizer Module (SKIM), if PCM is replaced, the secret key data must also be updated to enable engine starting. To update secret key data, see POWERTRAIN CONTROL MODULE  under PROGRAMMING.