CONTROL GP-ELECTRONIC 4727687 - Caterpillar

Alternator "R" Terminal
The secondary steering electronic control module (1) is connected to alternator "R" terminal (5). After engine start up, voltage from alternator "R" terminal (5) activates an internal latch (electronic "fastener") in the secondary steering electronic control module (1), which activates the automatic secondary steering system. After start up, the latch makes the secondary steering system independent of the alternator "R" terminal current. It is unlatched by the disconnect switch or the key start switch.Secondary Steering Pressure Switch
View Is From Left Side Under Operator's Platform
(4) Secondary steering pressure switch. (13) Combination valve group.Secondary steering pressure switch (4) is mounted in the combination valve (13). When in normal operation and primary steering system pressure falls below approximately 700 kPa (100 psi) (either as a result of engine failure or primary hydraulic system failure upstream of the steering valve), secondary steering pressure switch (4) opens. This provides the input to the secondary steering electronic control module to turn secondary steering ON. Primary hydraulic pressure must return to 1206 kPa (175 psi) or above to close secondary steering pressure switch (4).Secondary Steering Electronic Control Module
Left Front Of Engine Compartment (16H Shown)
(1) Secondary steering electronic control module.
EMS Panel
(14) EMS action light. (15) Secondary steering light.
(7) Secondary steering motor status light. (8) Secondary steering switch.Secondary steering electronic control module (1) controls the three second power-up test and controls automatic actuation of the secondary steering system.The following condition(s) must exist before secondary steering electronic control module (1) actuates the secondary steering motor (12) and motor status light (7) in secondary steering switch (8):* Secondary steering electronic control module (1) must have been actuated (placed in ready position) by voltage from alternator "R" terminal (5).* Loss of hydraulic oil pressure.* Secondary steering pressure switch (4) is open.With these conditions present, secondary steering electronic control module (1) closes the secondary steering magnetic switch (11). This completes the circuit to the secondary steering motor and to motor status light (7) in secondary steering switch (8). At the same time, secondary steering electronic control module (1) actuates secondary steering light (15), EMS action light (14) and the action alarm.Secondary Steering Magnetic Switch And Secondary Steering Motor
(11) Secondary steering magnetic switch.
(12) Secondary steering motor.The motor can also be actuated by holding spring loaded secondary steering switch (8) in the ON position. With the key start switch ON, this action will bypass secondary steering electronic control module (1) and it's two sensor inputs and closes magnetic switch (11), turning ON secondary steering motor status light (7). This position of the secondary steering switch is generally used only to test the secondary steering pump and the secondary steering motor status light, or turn the front wheels while testing the system. The secondary steering pump motor is mounted to the left of the front frame under the operator's platform.
The machine's batteries must have a normal charge and the secondary steering electrical system must be okay. A low charge condition, or any defect in the battery, battery cells, or electrical circuit can