Vehicle Application: 2000 F-250 Super Duty 7.3
Customer Concern: The engine misfires badly and keeps resetting codes P1272, P1273. The valve cover gaskets and Under Valve Cover (UVC) harnesses are in good condition and some of the injectors have been swapped to different cylinders but the codes haven't changed.
Tests/Procedures: 1. Access the Injector Driver Module (IDM) in the Left Hand (LH) fender.
2. At the IDM swap the Tan wire at pin 6 with the Brown/Yellow (BN/YE) wire at pin 21. This will swap the wires for injectors 1 and 3. Clear the codes and redo the injector buzz test. If the codes stay the same, replace the IDM.
3. If the code P1273 changes to a P1271, check for high resistance in the engine wiring harness between the IDM and valve cover gasket. Start with looking for a problem at connector C138 (42 terminal connector near the LH valve cover). Repair the wiring as needed and recheck operation.