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Revision A
6.1.1
AHHC Sensor Operation
1025389
A
B
C
Figure 6.1: Variable Resistor Type Sensor
The position sensors supplied with the auto header height
control (AHHC) system are 1000 ohm (1 k) industrial series
variable resistor consisting of a sealed unit with a three-pin
connection point (A) and two mounting holes (B). A signal
wire is connected internally to a movable wiper (C) that
sweeps across a high resistance filament band. An external
arm is attached to the movable wiper (C) and as it moves,
the wiper moves across the resistance filament to change
the resistance at signal wire, which changes the output
voltage. The resistance across the power and ground pins
should be approximately 100 ohms. Normal operating
signal voltages are 0.5
–
4.5 VDC or 5
–
95% of available
voltage.
•
A sensor operating with a signal voltage
below 5%
is
considered to be shorted.
•
A sensor with a signal voltage
above 95%
is considered to be open.
•
A change in header height will cause the voltage signal to change.
6.1.2
Height Sensor Output Voltage Range
–
Combine Requirements
The height sensor output must be within a specific voltage range for each combine or the auto header height
control (AHHC) feature will not work properly.
Table 6.1 Combine Voltage Range
Combine
Low Voltage Limit
High Voltage Limit
Minimum Range
Case IH 7/8010, 5/6/7088,
7/8/9120, 5/6/7130, 5/6/7140,
7/8/9230, 7/8/9240
0.7 V
4.3 V
2.5 V
John Deere 60/70/S/T Series
0.7 V
4.3 V
2.5 V
New Holland CR/CX
–
5 V system
0.7 V
4.3 V
2.5 V
New Holland CR/CX
–
10 V system
3.0 V
7.0 V
4.1
–
4.4 V
NOTE:
For instructions on manually checking voltage range, refer to
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