Data Link Communications Circuit Description All Engines

The engine control module (ECM) and the electronic brake control module (EBCM) (air), if equipped, are accessed by the scan tool through CKT 1921 (TAN) and CKT 1921 (WHT). The scan tool also accesses the ECM through CKT 1807 (PPL). On gas models, the PCM is accessed through CKT 461 (ORN) and CKT 448 (WHT/BLK). The scan tool accesses the electronic brake control module (hydraulic), if equipped, through CKT  799 (TAN/WHT).

These communication lines monitor the modules for diagnostic purposes and checks for diagnostic trouble codes (DTCs). Voltage is applied at all times to the DLC through the IGN 3 circuit breaker. The DLC is permanently grounded to G102 and G101.