How To Use Circuit Tests

WARNING: This page is about a different car, the 1994 Mercury Tracer and 1994 Ford Escort. However, it is still accessible from the selected car via links, so may be relevant.

1) DO NOT perform any circuit test unless specifically instructed by a procedure under QUICK TEST or SWITCH MONITOR TEST. Ensure all non-EEC related faults are corrected. Follow each test step in order until fault is found. When more than one code is received, start with first code displayed.

2) Use circuit tests to check electrical circuits before replacing sensors or any other components. Always test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to ground.

3) DO NOT connect any test light or measure voltage or resistance at PCM unless specified in testing procedure. DO NOT pierce wiring. If backprobing is specified, always backprobe harness side of connector. DO NOT probe connector side.

4) Isolate both ends of circuit and turn ignition off whenever checking for shorts or continuity, unless specified otherwise. Disconnect solenoids and switches before checking circuit continuity or energizing solenoids.