Colored Schematic
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| Illustration 1 | g01232110 |
Power Distribution
The 119-PK wire transfers power from "CB2" to the following contacts:
- Contact "A" of the steering mode sensor
- Contact "A" of the front track position sensor
- Contact "A" of the rear track position sensor
Terminal "1" of the machine ECM also receives power through the 119-PK wire.
Input Signals
The machine ECM monitors the circuit at terminal "16" and the circuit at terminal "17" in order to determine the position of the rotor service door. If the rotor service door is open, the machine ECM will not operate the rear steering solenoids.
Note: For additional information refer to the rotor drive system in this module.
The machine ECM uses the steering mode sensor in order to monitor the position of the steering mode switch. Contact "C" of the steering mode sensor transmits a pulse width modulated signal to terminal "29" of the machine ECM. The machine ECM reads the duty cycle of the signal and then the machine ECM determines the position of the steering mode switch.
Contact "C" of the front track position sensor transmits a pulse width modulated signal to terminal "3" of the machine ECM. Contact "C" of the rear track position sensor transmits a pulse width modulated signal to terminal "4" of the machine ECM. The machine ECM uses these input signals in order to determine the position of the tracks.
COORDINATED and CRAB Steering Modes
In the COORDINATED steering mode and the CRAB steering mode, the machine ECM uses the signal from the front steering sensor as the reference. When the steering wheel is moved, the machine ECM senses the change in position of the front tracks. This change prompts the machine ECM to generate an output signal to the appropriate rear steering solenoid. The L937-BR wire carries the signal from terminal "33" of the machine ECM to the left rear steering solenoid. The L938-BU wire carries the signal from terminal "34" of the machine ECM to the right rear steering solenoid.
Note: In the COORDINATED steering mode, the machine ECM turns the rear tracks in the opposite direction of the front tracks. In the CRAB steering mode, the machine ECM turns the rear tracks in the same direction as the front tracks.
The machine ECM discontinues the output to the rear steering solenoid in the following conditions:
- The front track position sensor indicates that the front track movement has stopped.
- The rear track position sensor indicates that the rear tracks have moved to the same degree as the front tracks.
The machine holds the current steering position until the steering wheel is moved again.
FRONT Steering Mode
In the FRONT steering mode, the machine ECM uses the input from FRONT steering mode the rear steering sensor in order to center the rear tracks. The machine ECM holds the rear tracks in the calibrated straight travel position, regardless of the position of the front tracks.
REAR Steering Mode
In the REAR steering mode, the front and rear tracks are controlled independently. In this mode, the steering wheels control the position of the front tracks, and the rear steering switches control the position of the rear tracks. The machine ECM monitors the input from the rear steering switches in order to determine the desired travel direction. When both rear steering switches are in the OFF position, the circuit at terminal "21" of the machine ECM and the circuit at terminal "24" of the machine ECM are open. These open circuits tell the machine ECM to hold the rear tracks in the current position.
When either rear steering switch is moved into the RIGHT position, the circuit at terminal "24" of the machine ECM is complete. In this case, the machine ECM generates an output signal at terminal "34", and the rear tracks turn clockwise. When either rear steering switch is moved into the LEFT position, the circuit at terminal "21" of the machine ECM is complete. In this case, the machine ECM generates an output signal at terminal "33", and the rear tracks turn counterclockwise.