LOCK 5S6921 - Caterpillar

Note: With the release of Tier 4 Interim/Final engines, additional emissions control system components have been added to the engine to reduce the NOx output. The addition of these components requires three Electronic Control Modules (ECMs) for the engine and aftertreatment systems to operate. The most recent version of Cat® Electronic Technician (ET) must be used when connecting to the Electronic Control Modules. Refer to Special Instruction, REHS8170 for instructions on properly setting up the computer and Comm3 adapter for use on Tier IV applications. When viewing the Diagnostic or Event Codes screens, ensure that the "Include All ECM's" box is checked.Override Parameters
The override parameters screen has multiple overrides. The parameters control various functions on the engine and Clean Emissions Module (CEM). These functions and features allow the technician to troubleshoot different engine systems.Cat ET Location
Connect to Cat ET.
Select the appropriate ECM.
Select the "Diagnostics" tab.
Select the "Diagnostic Tests" tab.
Select the "Override Parameter" tab.Override Parameters Listed in the Engine ECM Menu
Engine Pre-Lube Override
This override turns on the Engine Pre-Lube relay to test the power supply circuit to the relay.Engine Overspeed Test
This test is used to test the engine overspeed shutdown protection system. When this test is activated, the ECM will temporarily lower the engine overspeed shutdown limit to 75% of the normal value. The usual method of engine speed control is then used to raise the engine speed above the temporary speed threshold. The ECM will then disable injection and shut the engine down. Once the test is complete, the ECM must be reset using a keyswitch cycle before the engine can be restarted.Starting System #1 Relay Override
This override turns on the starting system #1 relay to test the power supply circuit to the relay.Starting System #2 Relay Override
This override turns on the starting system #2 relay to test the power supply circuit to the relay.Override Parameters Listed in the Selective Catalyst Reduction Menu
Aftertreatment #1 DEF Return Valve Override
This override turns on the DEF Return Valve circuit to test the return valve and the circuit for proper operation.Aftertreatment #1 SCR Dosing Air Assist Valve Command Override
This override turns on the DEF Air Assist Valve circuit to test the air assist valve and the circuit for proper operation.Engine Exhaust NOx Level Sensor Power Supply Override
This override turns on the NOx sensor power supply to the engine out NOx sensor to test the power supply circuit and the NOx sensor.Aftertreatment #1 Outlet #1 NOx Level Sensor Power Supply Override
This override turns on the NOx sensor power supply to the engine out #1 NOx sensor to test the power supply circuit and the NOx sensor.Aftertreatment #1 DEF Manifold Heater Relay Override
This override turns on the DEF Manifold Heater to test the power supply circuit to the DEF Manifold heater.Aftertreatment #1 DEF Tank Refill Solenoid Override
This override turns on the DEF tank refill valve circuit to test the refill valve and the circuit for proper operation.Aftertreatment #1 DEF Pump Heater Command Percentage Override
This override is used to turn the DEF pump heater ON