Engine Protection Mode System

03 through 05 model years -Remote Mounted Horn System:

Horn operation: The only difference in horn operation between the two systems is that the remote horn system doesn’t activate the warning horn for active DTC’s. All other horn functions are unchanged

System operation: The exhaust temperature switches input has been moved from the oil pressure switch input circuit to a new circuit at J1-19. This circuit is the “General Warning #1 Input”circuit. These switches are the only items on the general warning # 1 input circuit. Once the engine has been running approximately 20seconds, if one of the exhaust temperature switches closes (due to high temp), S.L.O.W.mode is activated, the warning horn sounds a steady beeping sound and a “General Warning # 1”fault code is set in the ECM’s memory. The oil pressure switch input is still located on J2-20, but it is the only item on that circuit. While S.L.O.W. mode is activated, if the switch that activated S.L.O.W. mode returns to it’s normal state, the ECM waits approximately 20 seconds (to ensure that the change is valid) and then cancels S.L.O.W. mode.

The ECT input is monitored for S.L.O.W. mode also. If the enginecoolant temperature rises above a set value then S.L.O.W. mode is activated until the temperature drops below a set point. System operation and diagnosis is covered in the 7742218 diagnostic book on pages 255 through 259.

While in S.L.O.W. mode, in addition to sounding the warning horn, the ECM kills ½of the fuel injectors anytime the RPM exceeds 2500. The ECM turns them back on once RPM has dropped below 1200.