WARNING: This page is about a different car, the 1997 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

Turn ignition off. Disconnect GEM connector C239 located behind center of instrument panel. See Fig 1 . Inspect connector C239 and Data Link Connector (DLC) C228 for physical damage, bent terminals or corrosion. Repair as necessary and retest system. If connectors are okay, go to next step.
Measure resistance of Light Blue/White wire between GEM connector C239, terminal No. 25 and DLC C228, terminal No. 7. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Blue/White wire between GEM connector and DLC C228. Retest system.
Reconnect GEM connector C239. Perform data link diagnostics. See DATA LINK DIAGNOSTICS under COMMUNICATION NETWORK DIAGNOSTICS. If GEM responds to NGS tester, system is functioning properly. If GEM does not respond to NGS tester, check power and ground circuits to GEM. See WIRING DIAGRAMS . If fault is found, repair as necessary and retest system. If no fault is found, replace GEM and retest system.

Fig 1: Identifying GEM Connector C239

Courtesy of FORD MOTOR CO.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Test C: Generic Electronic Module (Gem) Does Not Respond To NGS Tester

Use the Manual With the Right Hardware

When to See a Mechanic

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