Diagnostic Aids

The following information should be noted during testing:

• All voltage readings given in test procedures are based on values obtained using a standard DVOM such as Rotunda (007-00001) or Fluke (20 or 70 Series). To ensure actual A/C voltage readings taken are consistent with A/C voltage readings in PINPOINT TESTS, DO NOT use a RMS type meter (such as Fluke 8060a).
• When instructed to inspect a wiring harness, perform both a visual inspection and a continuity test.
• When making voltage checks, ground connections should be made at negative battery terminal or cast iron surface of engine.
• When making measurements on a wiring harness or connector, perform a wiggle test while measuring.
• When making voltage checks, ground readings are defined as a value of less than 1.0 volt. Battery voltage is defined as a value of more than 10 volts.
• When performing CIRCUIT TEST procedures, circuits are identified in all capital letters; for example: PIP. Manufacturer's breakout box overlay test terminals are identified by a "J" prefix; for example: J15 (PIP). This indicates test terminal number and circuit identification.
• Test procedures intended to identify faulty components/wiring while fault is present. If complaint is an intermittent condition, refer to TESTS W/O CODES - 5.0L article or CIRCUIT TEST Z in TESTS W/CODES - 5.0L article.
  1. Check For Diagnostic Trouble Codes (DTC)  Perform QUICK TEST. See TESTS W/CODES - 5.0L article. If DTCs are present, service codes as necessary. If codes are not present, go to next step.
  2. Check Battery  Turn ignition on. Check battery voltage. If battery voltage is less than 12 volts, service battery as necessary. If battery voltage is more than 12 volts, go to next step.
  3. Check For Spark  Using Spark Tester (D81P-6666-A Or D89P-6666-A), check for spark at each spark plug wire while cranking. If spark is consistent at all spark plug wires, go to next step. If spark is not consistent, go to CIRCUIT TEST JL models, go to CIRCUIT TEST JD in TESTS W/CODES - 5.0L article.
  4. Check Spark Plugs  Remove and inspect spark plugs. Replace plugs as necessary. If spark plugs are okay, testing is complete. If fault is still present, go to TESTS W/O CODES - 5.0L article. If vehicle has a no-start condition, go to CIRCUIT TEST A in TESTS W/CODES - 5.0L article. Problem is not ignition related.