Flow of Diagnosis

1. Verify the customer concern.
2. Visually inspect for obvious signs of electrical damage:

VISUAL INSPECTION CHART

Mechanical
- Switches

Electrical
- Bulbs
- Fuses
- Damaged wiring harness
- Loose or corroded connectors
- Generic Electronic Module (GEM)
- Fuse junction panel
- Relays
- Circuitry

3. If the concern remains after the inspection, connect the New Generation STAR (NGS) Tester to the Data Link Connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the NGS menu. If the NGS does not communicate with the vehicle:
- check that the program card is properly installed.
- check the connections to the vehicle.
- check the ignition switch position.

4. If the NGS still does not communicate with the vehicle, refer to the New Generation STAR Tester manual.
5. Perform the DATA LINK DIAGNOSTIC TEST. If the NGS responds with:
- CKT 914,CKT 915 or CKT 70 = ALL ECUS NO RESP/NOT EQUIP, refer to Information Bus.
- NO RESP/NOT EQUIP for GEM, go to Pinpoint Test A. A: No Communication With the Module - Generic Electronic
- SYSTEM PASSED, retrieve and record the continuous Diagnostic Trouble Codes (DTCs), erase the continuous DTCs, and perform self-test diagnostics for the GEM.

NOTE: For vehicles built prior to February 5, 1998, the following criteria must be met when performing the GEM On-Demand Self-Test: headlamps and parklamps must be off and the power windows must be completely up. Failure to meet this criteria will result in DTCs B1577 and B2357 being set. For vehicles built after February 5, 1998, the following criteria must be met when performing the GEM On-Demand Self-Test: headlamps and parklamps must be on. Failure to meet this criteria will result in DTC B1575 being set.

6. If the DTCs retrieved are related to the concern, go to the GEM Diagnostic Trouble Code (DTC) Index to continue diagnostics. Diagnostic Trouble Code Tests and Associated Procedures
7. If no DTCs related to the concern are retrieved, proceed to Symptom Chart to continue diagnostics. Super Duty Series