Ford Pick-Ups/Expedition/Navigator 1997-2000

Diagnostic Link Connector


Some of the vehicles covered by this guide utilize two Diagnostic Link Connectors (DLCs), both of which are in the same vicinity.

The Diagnostic Link Connector(s) (DLC) may be found in the following location:

Under the hood near the firewall behind the driver's side strut tower.

The DLC is rectangular in design and capable of allowing access to 16 terminals. The connector has keying features that allow easy connection. The test equipment and the DLC have a latching feature to ensure a good mated connection.


Although stored codes may be read through the flashing of the CHECK ENGINE or SERVICE ENGINE SOON lamp, the use of hand-held scan tools such as Ford's Self-Test Automatic Readout (STAR) tester or the second generation SUPER STAR II tester or their equivalent is highly recommended. There are many manufacturers of these tools; the purchaser must be certain that the tool is proper for the intended use.

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 collecting information easier, but the data must be correctly interpreted by an operator familiar with the system.

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Fig. Fig. 1 Super Star II tester-Ford Motor Co.

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Fig. Fig. 2 Inexpensive scan tools, such as this Auto Xray®, are available to interface with your Ford vehicle

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Fig. Fig. 3 An economically friendly alternative is this Code Scanner® from SunPro. They are purchased according to manufacturer and are available at many parts stores

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Fig. Fig. 4 The Code Scanner® from SunPro has no LCD display, just a LED that will flash out the codes and an audible buzzer to alert that the test is in progress


The most commonly required electrical diagnostic tool is the digital multimeter, also known as a Digital Volt Ohmmeter (DVOM), which permits voltage, resistance (ohms) and amperage to be read by one instrument. Many of the diagnostic charts require the use of a volt or ohmmeter during diagnosis.

The multimeter must be a high impedance unit, with 10 megaohms 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.

Almost all diagnostic procedures will require the use of a Breakout Box, a device which connects into the EEC-IV harness and provides testing ports for the 60 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 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.