SWITCH-LIMIT 3792788 - Caterpillar

The following solenoids are often wrongly replaced:
155-4651 Solenoid (Fuel Shutoff) (12 volt)
155-4652 Solenoid (Fuel Shutoff) (24 volt)
155-4653 Solenoid (Fuel Shutoff) (24 volt)The following sections explain solenoid operation and also provide troubleshooting guidance.Construction
Illustration 1 g00736320
155-4651 Solenoid (Fuel Shutoff) and 155-4652 Solenoid (Fuel Shutoff) (1) Start terminal - positive (No. 8-32 THD) (2) Stop terminal - positive (No. 8-32 THD) (3) GND terminal - negative (No. 10-32 THD) (4) Plunger release button (manual override) (5) Plunger - in the ON position (latched) (6) Plunger - in the OFF position (unlatched) (7) Plunger spring
Illustration 2 g00765119
155-4653 Solenoid (Fuel Shutoff) - flange mount (8) GND terminal - negative (No. 10-32 THD) (9) Start terminal - positive (No. 8-32 THD) (10) Stop terminal - positive (No. 8-32 THD) (11) Flange (12) Plunger - in the ON position (latched) (13) Plunger - in the OFF position (unlatched) (14) Plunger spring (15) Plunger release button (manual override)
Illustration 3 g00765161
Schematic symbol (16) Stop terminal (17) Stop coil (18) Ground terminal (19) Internal switch (20) Start coil (21) Start terminalThe major parts of a solenoid are listed below:Start Coil - The start coil (20) is energized when the key switch is in the START position.Stop Coil - The Stop Coil (17) is energized when the key switch is in the OFF position.Internal Switch - The internal switch (19) controls the operation of the start coil and the stop coil.Plunger - The plunger (5,6,12,13) is retracted for engine run mode. The plunger is extended for engine stop.Plunger Spring - The plunger spring (7,14) pushes the plunger outward to the STOP position.Permanent Magnet - For the run mode, the permanent magnet holds the plunger inward.Plunger Release Button - If electrical system power is not available, the plunger release button (4,15) allows the engine to be shutdown manually. Operation
When the key switch is turned to the start position, the start coil is energized. Current flows through the start coil through the internal switch. Current exits the start coil through the ground terminal. A magnetic field is created by the start coil. This magnetic field retracts the plunger.
When the plunger is in the retracted position (engine run position), the internal switch opens the start coil circuit. When the permanent magnet holds the plunger in the engine run position, no current flows through the solenoid.
When the key switch is turned to the OFF position, the stop coil is energized. After the stop coil is energized, current will flow in the following pattern: through stop coil, through internal switch and out ground terminal. The magnetic field that is created by the stop coil cancels the permanent magnet's magnetic field. In order to stop the engine, the plunger spring pushes the plunger outward. When the plunger is fully extended (stop position), the internal switch opens the stop coil circuit.Troubleshooting
If a problem is suspected with the operation of the solenoid, perform the following checks before replacing the solenoid. In order to perform this procedure, choose one of the multimeters from Table 1.
Table 1
TOOLS NEEDED    
Tool     Part