LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 2001 >> Expedition 4.6 W, RWD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Module Communications Network >> System Tests >> Test C: Generic Electronic Module Does Not Respond To NGS Tester
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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

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.
  1. 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.
  2. 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.
  3. 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.