KIT-SERVICE 2012157 - Caterpillar

Introduction
994D Wheel LoaderThe 994D Wheel Loader is equipped with the latest state-of-the-art electronic machine control and monitoring technology. This guide provides a general overview of each electronic system along with a troubleshooting guide which explains how to use the various troubleshooting tools, techniques and component locations.Features
Power Train Electronic Control System
Power Train Electronic Control System Block DiagramThe Power Train Electronic Control System performs the shifting of the transmission. The electronic control module (ECM) responds to the shifting requests of the operator by activating the appropriate clutch solenoid valves which then allow oil to flow to the corresponding transmission clutches. In addition to the shifting function, the ECM also controls the neutral start function and the backup alarm function.* STIC Controller - The direction, upshift and downshift switches, located in the STIC controller, tell the ECM the requests of the operator; forward, reverse, neutral, upshift or downshift. The ECM acts upon the shift requests by activating the appropriate transmission clutch solenoid valves. Except for certain conditions, the ECM shifts the transmission as requested by these switches.* Transmission Clutch Solenoid Valves - These clutch solenoid valves, located on the transmission, direct pilot oil to the ends of the control spool. The control spool will shift allowing pressure oil to the corresponding clutches. The ECM decides which clutch solenoid valves to activate, based on the input from the direction, upshift and downshift switches (STIC controller). Clutch solenoid valves 1 and 2 are for direction. Clutch solenoid valves 3, 4, and 5 are for speed. For movement of the machine two clutch solenoid valves are activated; one for direction and one for speed. When in neutral, only clutch solenoid valve 3 is activated.Also featured is a electronic torque converter. The ECM controls the impeller clutch and lockup clutch functions of the torque converter. These machines also have an additional feature called Reduced Rimpull. This allows the operator to select a preset amount of rimpull reduction desired.The power train ECM communicates with other electronic controls on the machine using the CAT data link. This data link allows the power train ECM to send and receive information throughout the machine between the various control modules. The CAT data link is not a visible component.Calibration and service code information can also be shown on the service tools, Caterpillar Electronic Technician and VIMS-PC.For detailed information on operation and troubleshooting of the power train system, refer to RENR2522, Power Train Electronic Control System.Vital Information Management System (VIMS)
Vital Information Management System (VIMS) Block Diagram
VIMS Message Center Module
(1) Alert indicator. (2) Data logging indicator. (3) Message area. (4) Universal gauge. (5) Gauge warning area.
Keypad
(6) Backward arrow key. (7) Forward arrow key. (8) Gauge key. (9) Key pressed indicator.The Vital Information Management System (VIMS) are electronic monitoring systems that continuously monitor machine systems. The main VIMS module makes decisions based upon input from the VIMS interface module(s), VIMS keypad, other