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

WARNING: This page is about a different car, the 2002 Lincoln Navigator, 2002 Ford Expedition, 2001 Lincoln Navigator, and 2001 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Disconnect battery before disconnecting GEM connectors. Failure to do so will result in GEM storing erroneous codes and may also result in erratic operation after connection of GEM.

NOTE: After making any repair, perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM.

Turn ignition switch to LOCK position. Disconnect negative battery cable. Disconnect Generic Electronic Module (GEM) 26-pin harness connector C239. GEM is located on back side of central junction box. Inspect GEM harness connector for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
Measure resistance in Light Blue/White wire between GEM harness connector C239 terminal No. 25 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Light Blue/White wire between GEM and DLC.
Connect GEM harness connector C239. Connect negative battery cable. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM. If GEM responds to NGS tester, system is functioning properly. If GEM does not respond to NGS tester, replace GEM. See GENERIC ELECTRONIC MODULE under REMOVAL & INSTALLATION.