COMPARTMENT AS 4V6956 - Caterpillar

E575 - Unexpected Drive Motor Forward Speed Detected, E576 - Unexpected Drive Motor Rearward Speed Detected
Note: The following description applies only to Event codes E575 and E576.An Event Code will display when the following occurs:The Machine ECM is programmed to determine when an Uncommanded Movement Detected (UCMD) event occurs. When the machine speed is greater than 1.0 km/h (0.6 mph), this logic will stop machine movement under the following conditions:
The actual ground speed is higher than the commanded speed for a duration of time. The default speed differential is set at 20 percent. The default time is set at 250 ms.
The actual machine direction is opposite the commanded direction for a specified amount of time.If the Machine ECM detects UCMD, the system generates a Level 3 fault. An active UCMD will disable all propel, and vibe system functions. Propel command will go to zero and the parking brake and two-speed solenoids will be de-energized, causing the parking brake to be applied.If either of these situations should occur, one of the following Event Codes will display.
E575 - Unexpected Drive Motor Forward Speed Detected
E576 - Unexpected Drive Motor Reverse Speed Detected
Illustration 1 g02918422
Solid Drum CD44B and CB44B Machine Speed Sensors Schematic
Illustration 2 g02918456
Solid Drum CD54B and CB54B Machine Speed Sensors Schematic
Illustration 3 g02917837
Split Drum Machine Speed Sensors Schematic
The Machine ECM monitors input speed signals from the Drum Speed Sensors in order to determine the actual machine speed and direction. Each Speed Sensor has a 4 pin connector. Contact 1 of each speed sensor receives 8 V power. Each speed sensor provides two pulsed output signals to the Machine ECM. Solid Drum machines "CD44B" and "CB44B" use contacts 3 and 4. Solid Drum machines "CD54B" and "CB54B" and Split Drum machines use contacts 2 and 4. The remaining contact is the ground (GND).The Machine ECM compares the frequency of the two output signals from the front Drum Speed Sensor. The ECM also compares the frequency of the two output signals from the rear Drum Speed Sensor. Split Drum machines will have four speed sensors for a total of 8 output signals. Reference illustration 4 below for a basic electrical schematic. If internal signals from any one sensor are out of sync, the Machine ECM generates a Level 2 fault. In this case, the ECM sets the propel mode to low, and the UCMD detection logic and the vibratory system are disabled.
Illustration 4 g02803498
Schematic for the Drum
The ECM averages the input from the front and rear sensors to calculate the machine speed. The Machine ECM compares the observed machine speed to the desired machine speed.Inputs used to measure the difference between the actual travel speed and travel speed commanded by the operator are:
Motor Speed
Engine Speed
Propel speed range (Hi/Low)
Propel speed control
Propel lever positionThe key switch must be cycled before the event will be cleared and the machine will be allowed to operate.Causes of an Uncommanded Movement Detected (UCMD) Event
The Pump Stuck at Maximum Displacement - The motor will be running at maximum speed and higher than commanded