The main module monitors the voltage of the machine electrical system. The control measures the system voltage. The control then determines whether the system voltage is within specified limits. The voltage is measured at contact 1 (+battery) of the main module.
Other Electrical Components
Some machines have electronic control modules that are not part of the VIMS, but the electronic control modules communicate with the VIMS. The CAT data link connects these electronic controls together. This allows the sharing of information such as engine oil pressure, engine speed, harness codes and diagnostic information. For example, an engine control sends engine speed information to the main module over the CAT data link. In this situation, the engine speed sensor is not part of the VIMS.
Solenoids
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| Illustration 1 | g00482940 |
(1) Solenoid (2) Schematic symbol | |
The solenoid is used in order to allow "VIMS" to cause action. This action could be activating a lube system or stopping the engine.
Warm Up Solenoid Valves
Warm up solenoid valves are used by the large hydraulic excavators in order to ensure that the hydraulic controls work smoothly. Hydraulic oil is allowed to flow through the main control valve spool for each implement during periods of hydraulic inactivity. The solenoid is de-energized during this time. When hydraulic activity is resumed the VIMS module energizes the solenoid in order to close the warm up valve. This stops the warm up oil flow through the main control valves. The VIMS module uses the information that is received from the electronic engine control in order to regulate the operation of the solenoids.
Diode Assemblies
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| Illustration 2 | g00482941 |
(1) Schematic symbol of the type A diode assembly (2) Schematic symbol of the type B diode assembly (3) Diode assembly | |
Diode assembly (3) is installed at all solenoids that are NOT activated by an electronic control module. The assembly is installed between the machine harness and the solenoid. These solenoids could include various hydraulic solenoid valves and the horn solenoid. Using the diode assemblies reduces the amount of electrical noise that is created by the operation of these solenoids. Electrical noise can cause erratic operation of the VIMS. The type A diode assembly is used on most solenoids. The type B diode assembly is used on the air conditioner clutch solenoid.
Service Key Switch
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| Illustration 3 | g00482942 |
Service Key Switch (1) Key switch (2) Schematic symbol | |
The service key switch is used in order to access the VIMS without turning the key start switch of the machine to the ON position.