How To Use Circuit Tests

1) DO NOT perform any CIRCUIT TEST unless directed to do so by a QUICK TEST procedure. Ensure all non-EEC related faults are corrected. FOLLOW EACH TEST STEP IN ORDER UNTIL FAULT IS FOUND. DO NOT replace any part unless directed to do so. When more than one service code is received, start with the first code displayed.

2) CIRCUIT TESTS require that you prove the electrical circuits are okay before you replace sensors or any other components. Always test circuits for continuity between the sensor and the ECA. Test all circuits for shorts to power, opens, or shorts to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with KOEO or as specified in the specific CIRCUIT TESTS (TESTS A1 to D3).

3) DO NOT measure voltage or resistance at ECA or connect any test light, unless specified in testing procedure. DO NOT pierce wiring. If backprobing is specified, always backprobe harness side of connector, never the connector side. Isolate both ends of a circuit and turn key off whenever checking for shorts or continuity, unless specified.

4) Unless otherwise specified, an open circuit is defined as a circuit which has a resistance greater than 5 ohms. Disconnect solenoids and switches before checking circuit continuity or energizing solenoids.

5) A short is defined as any resistance to ground of less than 10,000 ohms, unless otherwise specified.

NOTE: In the following tests, circuits and illustrations are supplied courtesy of Ford Motor Co. Complete EEC system wiring diagrams may be found at the end of this article.