AIR-COOLER 4174953 - Caterpillar

Illustration 1 g00326430
Back of the Status Control Module (SCM) (1) Overspeed verify switch.The SCM will allow the service personnel to verify that the engine overspeed protection is functioning. Actual overspeeding of the engine is not required. Activation of the overspeed verify switch will reduce the overspeed setpoint to 75 percent of the value that is programmed in the SCM. Therefore, the speed for overspeed verify is less than the rated engine speed.
Operate the engine at rated speed. Monitor the gas shutoff valve and the signal for the ignition shutoff.
The engine speed should be below 75 percent of the overspeed setting value. Depress the overspeed verify switch (1) and hold the switch. Slowly bring the engine up to speed. The SCM will shut the engine down within one or two rpm of the 75 percent verify value. This will tell you that the SCM works correctly and also that the overspeed setting is correct. Release the switch after the engine stops.
Check that the gas shutoff valve and the signal for the ignition shutoff caused the engine to shut down. Also, check that the overspeed indicator on the SCM is flashing.
Turn the Engine Control Switch (ECS) to the OFF/RESET position.