FUEL SOLENOID SAVER DIODE ('94-'98, 5.9L)

Save the fuel solenoid in '94-'98, 12-valve Dodge Cummins Turbo Diesel trucks from burning up if the starter sticks on.

Fuel solenoid failure almost always begins with worn starter contacts. When a starter sticks on it is caused by the worn contacts arcing and becoming welded together. When this happens the starter backfeeds 12v up thorugh the trigger circuit to the 70 amp fuel solenoid relay. The relay then thinks it is getting power from the ignition switch so closes the relay and energizes the fuel solenoid via the "pull" coil. This is why the engine won't shut off by the key. This "pull" coil is very strong, but low resistance so it will overheat very quickly if allowed to stay energized. This is what causes the fuel solenoid to burn up.

So, by installing this one-way diode to the starter solenoid trigger and preventing the starter from backfeeding the fuel solenoid circuit, we save the fuel solenoid from burning up if the starter sticks on. It also allows the engine to be turned off. Again, this is the primary cause of fuel solenoid failure. A diode lets current flow one way, but not the other.