818883A 1 Mercury THUMB SCREW ASSEMBLY

Illustration 1 g00567869
ETS Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) that does not require a switchgear for use on 3200 through 3400 Engines (1) Terminal strips (TS) (2) Wiring harness (3) Electronic speed switch (ESS) (4) Junction box (5) Identification foil (6) Jumper between terminals (TS-2) and (TS-3) (7) Jumper between terminals (TS-3) and (TS-4) (8) Emergency stop switch (ES) (9) Time delay relay (TD) (10) Jumper between terminals (TS-27) and (TS-28) (11) Jumper between terminals (TS-28) and (TS-29) (12) Jumper between terminals (TS-30) and (TS-31) (13) Slave relay (SR1) (14) Slave relay (SR2) for the air shutoff solenoid (ASOS) (if equipped) (15) Grommet assembly for engine oil pressure switches (16) Start/stop switch (SSS) (17) Circuit breakers (18) Engine oil pressure switch (OPS1) (19) Mounting brackets for grommet assemblies
Illustration 2 g00290530
ETS Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) that does not require a switchgear for use on 3500 Engines (1) Terminal strips (TS) (2) Wiring harness (3) Electronic speed switch (ESS) (4) Junction box (5) Identification foil (6) Jumper between terminals (TS-2) and (TS-3) (7) Jumper between terminals (TS-3) and (TS-4) (8) Emergency stop switch (ES) (9) Time delay relay (TD) (10) Jumper between terminals (TS-27) and (TS-28) (11) Jumper between terminals (TS-28) and (TS-29) (12) Jumper between terminals (TS-30) and (TS-31) (13) Slave relay (SR1) (14) Slave relay (SR2) for the air shutoff solenoid (ASOS) (if equipped) (15) Slave relay (SR3) for starting aid switch (if equipped) (16) Diode for electric governor actuator (if equipped) (17) Grommet assembly for engine oil pressure switches (18) Start/stop switch (SSS) (19) Circuit breakers (20) Engine oil pressure switch (OPS1) (21) Mounting brackets for grommet assemblies (22) Engine oil pressure switch (OPS2) (if equipped)Introduction
The ETS Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) that does not require a switchgear is a system that has full protection. The system has a junction box arrangement that is designed to monitor four functions:
Engine overspeed
Crank termination
Oil pressure
Coolant temperatureThe junction box includes the following components:
Electronic speed switch (ESS) (2)
Start/stop switch (SSS) (18) and (16)
Slave relay (SR1) (13)
Slave relay (SR2) (if equipped) with an air shutoff solenoid (ASOS) (14)
Oil pressure switch (OPS1) (18) and (20)
Oil pressure switch (OPS2) that is only in 3500 Engines (22)
Emergency stop switch (ES) (8)
Time delay relay (TD) (9) The components that are listed below operate with the junction box. The components are also mounted on the engine.
Fuel shutoff solenoid (FSOS)
Air shutoff solenoid (ASOS)
Water temperature switch (WTS)The following components must remain de-energized in order for the engine to run with the ETS electric protection system.
Slave relay (SR1)
Slave relay (SR2) (if equipped)
Fuel solenoid (FS)
Air shutoff solenoid (ASOS)Electrical Schematics And Wiring Diagrams
This manual contains the point-to-point wiring diagrams for the complete electric protection system and the junction box. Four types of electrical schematics for each electric protection system arrangement are shown in this service manual.
Junction box wiring diagram
IEC (International Electro-Technical Commission) schematic
JIC (Joint Industrial Council) schematic
Junction box wiring harness diagramNote: The line number that follows a component code gives the location of the component on the IEC and JIC schematics.Circuit Operation With No Faults
Engine Shutdown
When the engine is stopped, power is always available across the terminals (ESS-5) and (ESS-6) (line 53) of the electronic speed switch (ESS). Power is also available across terminals (TD-3) and (TD-4) (line 12) of the time delay relay (TD). All of the switches are in the normally open position or the normally closed positions at that time.Engine Start-up
Illustration 3 g00282739
5N-0364 Switch for 3500 Engines only (1) Keyway
Table 1
Switch Position     Contacts that are Closed    
START (A)     1-2 and 4-5    
RUN (B)     2-3 and 4-5    
STOP (C)     2-3 and 5-6    A toggle switch is located on the front of the junction box. The switch is spring loaded and the toggle switch is automatically returned to the RUN position. This happens when the toggle is manually released from the START position. This start/stop switch (SSS) has three positions:
START (A)
RUN (B)
STOP (C) When the start/stop switch is moved to the START position, the following events should occur in the electric circuit.
The start/stop switch closes the circuit to the starter motor.
The starter motor magnetic switch (SMMS) (line 9) closes a contact (line 3) which energizes the pinion solenoid (PS) (line 3).
The PS closes a contact (line 2) which energizes the starter motor (SM).When the toggle of the start/stop switch is held in the START position, power is always available to the starter motor until the engine begins to run. When the engine begins to run, the crank terminate switch (CT) stops the current that runs to the starter motor. When the engine begins to run, move the start/stop switch to the RUN position. If the engine oil pressure is too low to open the oil pressure switch (OPS1), the contacts across terminals (OPS1-1) and (OPS1-3) (line 15) open after the 9 second time limit. The slave relay (SR1) (line 36) is energized and the engine will shut down. Refer to "Fault Circuit Operation" for the complete circuit description under these conditions.Note: If an electric starting motor and an alternator are not used on the engine, connect the power source to the engine. Connect the positive lead of the power source to terminal (TS-1) and connect the negative lead to terminal (TS-28) of the junction box. If an electric starting motor is not used and an alternator is used, the battery can still be used to run the engine. Connect the battery cables to the studs for the power input which are located on the bottom of the power distribution box.Engine Mounted Start Switch (EMSS)
Illustration 4