See Figure 1
Although stored codes may be read using a suitable analog voltmeter, the use of a hand-held scan tool, such as Ford's Self-Test Automatic Readout (STAR) tester or the second generation SUPER STAR tester, or equivalent, is highly recommended. There are many manufacturers of such tools, but the purchaser must be certain that the tool is appropriate for the intended use.
Both the STAR and SUPER STAR testers are designed to communicate directly with the EEC-IV system and interpret the electrical signals. The scan tool allows any stored faults to be read from the engine controller memory. Use of the scan tool provides additional data during troubleshooting, but does not eliminate the use of the charts. The scan tool makes information collection easier, but the data must still be correctly interpreted by an operator familiar with the system.
OTHER DIAGNOSTIC TOOLS
The most commonly required electrical diagnostic tool is the digital multimeter, allowing voltage, ohms (resistance) and amperage to be read by one instrument. Many of the diagnostic charts require the use of a voltmeter or ohmmeter during diagnosis.
The multimeter must be a high impedance unit, with 10 megohms of impedance in the voltmeter. This type of meter will not place an additional load on the circuit it is testing; this is extremely important in low voltage circuits. The multimeter must be of high quality in all respects. It should be handled carefully and protected from impact or damage. Replace the batteries frequently in the unit.
Additionally, an analog (needle type) voltmeter may be used to read stored fault codes if the STAR tester is not available. The codes are transmitted as visible needle sweeps on the face of the instrument.
Although code retrieval does not require additional equipment, diagnostic procedures such as pinpoint testing will be easier with a "breakout box'', a device which connects into the EEC-IV harness and provides testing ports for the dozens of wires in the harness. Direct testing of the harness connectors at the terminals or by backprobing is not recommended; damage to the wiring and terminals is almost certain to occur.
Other necessary tools for testing/troubleshooting include a quality tachometer with inductive (clip-on) pickup, a fuel pressure gauge with system adapters and a vacuum gauge with an auxiliary source of vacuum.