How To Use System Tests

NOTE: Alternative Fuel Control Module (AFCM), may also be referred to as bi-fuel module. Tank select relay may also be referred to as LPG sender relay.

1) Ensure all non-EEC related faults found while performing basic diagnostic procedures in appropriate BASIC DIAGNOSTIC PROCEDURES article have been 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 code is retrieved, start with first code displayed.
2) System tests ensure electrical circuits are okay before sensors or other components are replaced. Always test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with ignition on or as specified in SYSTEM TESTS.
3) If measuring voltage or resistance at PCM and a breakout box is not available, always backprobe PCM connector. To identify PCM connector terminals, see Figure. DO NOT connect any test light unless specified in testing procedure. All measurements are made by probing rear of connector (wiring harness side). Isolate both ends of a circuit and turn ignition switch to OFF position when checking for shorts or continuity, unless instructed otherwise.
4) Disconnect solenoids and switches from harness before measuring continuity and resistance or applying voltage. After each repair, check all component connections and repeat QUICK TEST .
5) An open circuit is defined as a resistance reading of 5 ohms or more. This specification tolerance may be too high for some items in EEC-V system. If resistance approaches 5 ohms, always clean suspect connector and coat it with protective dielectric silicone grease. A short is defined as a resistance reading of 10,000 ohms or less to ground, unless stated otherwise in system test.
6) If instructed to replace Powertrain Control Module (PCM) after performing a system test, new PCM must be programmed. See POWERTRAIN CONTROL MODULE (PCM) under PROGRAMMING.

CAUTION: Perform all resistance and voltage tests with a Digital Volt-ohmmeter (DVOM) with minimum 10-megohm impedance, unless stated otherwise in test procedures. Ensure ignition switch is turned to OFF position when performing resistance tests.

NOTE: For identification of circuits, components, terminals and wire colors referenced in the following testing, see WIRING DIAGRAMS article. For connector locations, see CONNECTOR LOCATION table. To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem:

Fuel quality and quantity.
Ignition (general condition).
Engine mechanical components.
Starter and battery circuits.