Self-Diagnostic System
For preliminary testing, see TROUBLE SHOOTING . If problem is not found, connect New Generation Star (NGS) or Worldwide Diagnostic System (WDS) tester to Data Link Connector (DLC) located below center of instrument panel. See Fig 1. Using NGS/WDS tester, perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM in MODULE COMMUNICATIONS NETWORK - EXCURSION & F250-F550 SUPER DUTY PICKUPS article.
If NGS/WDS tester displays CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, diagnose module communications concern. See SELF-DIAGNOSTIC SYSTEM in MODULE COMMUNICATIONS NETWORK - EXCURSION & F250-F550 SUPER DUTY PICKUPS article.
If NGS/WDS tester displays NO RESP/NOT EQUIP for GEM, perform TEST A: NO SCAN TOOL COMMUNICATION WITH GEM under SYSTEM TESTS.
If NGS/WDS tester displays SYSTEM PASSED, retrieve and record continuous DTCs. Erase continuous DTCs. Perform Generic Electronic Module (GEM) self-test. If GEM DTCs related to the concern are retrieved, perform appropriate test. See GEM DTC INDEX table.
If no DTCs are retrieved, perform appropriate test based on symptom. See SYMPTOM INDEX table under SYSTEM TESTS. For GEM DTCs not covered in this article, see MODULE COMMUNICATIONS NETWORK - EXCURSION & F250-F550 SUPER DUTY PICKUPS article.
| DTC (1) | Description | Perform Test | ||||
|---|---|---|---|---|---|---|
| B1323 | Door Ajar Light Circuit Failure | S | ||||
| B1325 | Door Ajar Light Circuit Short To Power | S | ||||
| B1342 | ECU Defective | (2) | ||||
| B1426 | Seat Belt Warning Light Circuit Short To Power | T | ||||
| B1428 | Seat Belt Light Circuit Failure | T | ||||
| C1125 | Brake Fluid Level Sensor Input Circuit Failure | L | ||||
| C1189 | Brake Fluid Level Sensor Input Circuit Short To Ground | L | ||||
| C1223 | Brake Light Warning Output Circuit Failure | L | ||||
| C1225 | Brake Light Warning Output Circuit Short To Power | L | ||||
| C1446 | Park Brake Switch Circuit Failure | L | ||||
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