MANIFOLD-EXHAUST 9L5520 - Caterpillar

System Operation Description: When the local emergency stop switch on the control panel is depressed, the coils of relay "R4" and relay "R4A" are energized. The contacts of relay "R4" keep the coils of relay "R4" and relay "R4A" energized until the Engine Control Switch (ECS) is cycled to the OFF/RESET position. The contacts of relay "R4A" energize the coils of relays "R2" and "R2A". When relays "R2" and "R2A" are energized, power is removed from the engine's primary Electronic Control Module (ECM) and the engine's secondary ECM. The primary ECM and the secondary ECM will power down. The injection signals to the injector solenoids will stop. The emergency stop lamp on the control panel will illuminate.The contact of relay "R4A" also supplies power to terminal 3 of the connector for the timer. When power is applied to terminal 3 of the connector for the timer, the timer will activate. The timer outputs 24 VDC to terminal 6 of the connector for the timer for 2.5 seconds. The 24 VDC from terminal 6 of the connector for the timer is applied to the coil of the "Air Shutoff Switch (ASOS)". The contact of the "ASOS" energizes the air shutoff solenoids. The timer will output voltage to the coil of the "ASOS" for approximately 2.5 seconds. The "ASOS" will then deactivate and power is removed from the air shutoff solenoids. This prevents damage to the air shutoff solenoids. A normally open switch at the air shutoff valves will close when the air shutoff solenoid activates the air shutoff valve. The switch input to the ECM notifies the ECM that the air shutoff valves are closed. The ECM will not send injection signals to the injector solenoids until the switch inputs from the air shutoff valves indicate that the valves are open.Relay "R3A" and relay "R3" are energized at the same time as the "ASOS" through terminal 3 of the diode assembly. Terminal 3 of the diode assembly will energize relay "R3A" and relay "R3" for 2.5 seconds. The relays "R3A" and "R3" will de-energize after 2.5 seconds. The overspeed indicator on the control panel will illuminate for 2.5 seconds.In order to start the engine after an emergency stop condition, the ECS must be turned to the OFF/RESET position. This resets the ECM and the air shutoff timer. In addition to turning the ECS to the OFF/RESET position, the operator must manually open the air shutoff valves before starting the engine.
Illustration 1 g01322358
Typical example
Illustration 2 g01320528
Connector locations
(1) A-C1/E-C2 RH rigid harness connectors
(2) A-C2/J-C2 RH rigid harness connectors
(3) P-C1/A-C90 Connectors for the power distribution panel
(4) P-C2/A-C91 Connectors for the power distribution panel
(5) G-C6/F-C2/F-C1/A-C92 Connectors for a RH Control panel
(6) C-C22 Primary ECM connector P2
(7) C-C15 Primary ECM connector P1
(8) C-C28 Secondary ECM connector P2
(9) C-C29 Secondary ECM connector P1
(10) G-C6/F-C2/F-C1/C-C17 Connectors for