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Test F: Speedometer/Odometer Inoperative

CAUTION: Use correct test probe adapters when making measurements. Failure to use correct probe adapter may cause damage to connector.
NOTE: Perform all voltage and resistance tests using an Digital Volt-Ohm Meter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.
  1. Connect Worldwide Diagnostic System (WDS) tester or New Generation Star (NGS) tester to Data Link Connector (DLC), DLC is located below instrument panel. See Figure. Turn ignition switch to RUN position. Using WDS or NGS tester, monitor PCM Vehicle Speed Sensor (VSS) PID while driving vehicle at 30 MPH. If WDS or NGS tester displays 28-31 MPH, go to next step. If WDS or NGS tester does not display 28-31 MPH, repair speed signal circuit as necessary. See appropriate SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article in ENGINE PERFORMANCE. After repair, test system for normal operation.
  2. Turn ignition switch to LOCK position. Disconnect Powertrain Control Module (PCM) 104-pin harness connector C175, located at right rear of engine compartment. See Figure. Disconnect instrument cluster harness connector C220b, located behind instrument cluster. SeeFigure. It may be necessary to remove instrument cluster to access connectors. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Measure resistance between PCM harness connector C175 terminal No. 68 and instrument cluster harness connector C220b terminal No. 16 (Gray/Black wire). See Figure and Fig 1 . See WIRING DIAGRAMS . If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open circuit in Gray/Black wire between PCM and instrument cluster. After repair, test system for normal operation.
  3. Measure resistance between ground and instrument cluster harness connector C220b terminal No. 13 (Black/Yellow wire). See Figure. See WIRING DIAGRAMS . If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open circuit in Black/Yellow wire between instrument cluster and ground point located behind center of instrument cluster. SeeFigure. After repair, test system for normal operation.
  4. Remove instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Inspect instrument cluster printed circuit for contamination or damage. If instrument cluster printed circuit is faulty, replace instrument cluster printed circuit. See PRINTED CIRCUIT  under REMOVAL & INSTALLATION. If printed circuit is okay, replace speedometer. See SPEEDOMETER/ODOMETER  under REMOVAL & INSTALLATION. After repair, test system for normal operation.
    Fig 1: Identifying Powertrain Control Module Harness Connector C175 Terminals
    G00013160Courtesy of FORD MOTOR CO.
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