New Holland CX720 Repair Manual page 2548

E0179-05-LoP Isense Grnd Spd Hydro Line Disconnected
(C.20.F.91.11 - G.30.B.50)
E0179-05 - LoP Isense Grnd Spd Hydro Line Disconnected
Cause:
The Ground Speed Hydrostat Solenoid (L-23) circuit is open.
Possible failure modes:
1. Bad solenoid.
2. Return side wiring is open.
3. Controller internal failure (internal regulator failure).
Solution:
1. The LoP Isense Grnd Spd Hydro circuit is the ground path for the Ground Speed Hydrostat solenoid circuit.
By monitoring current flow on the return path of the ground speed hydrostat solenoid, the module can provide
precise control of the solenoid engagement. When this error message is reported, this is an indication of very
low current draw on the circuit, or an open circuit on the return line.
Enter the Infoview monitor - " Diagnose info" screen.
Select "Driveline" sub menu.
Select "LoP Isense Grnd Spd Hydro". Move the hydrostat handle to the full forward position, the full rearward
position, and back to neutral while monitoring the voltage.
With the hydrostat handle in neutral, the voltage indicated should be 0 volts.
With the hydrostat handle in the full forward position, the voltage indicated should be approximately 4.4 volts.
With the hydrostat handle in the full rearward position, the voltage indicated should be approximately 2.5 volts.
The fault code is generated If the current flow is less than 5 ma (0.2 volts indicated on bar graph) at any time
when the handle is out of neutral.
A. If one or both of the readings are less than 0.2 volts, continue with step 2.
B. If the readings are normal, continue the troubleshooting at step 7.
2. The voltage reading on the Infoview monitor is low. Turn the key switch to the OFF position and disconnect
the ground speed solenoid connector X100. Use a multimeter to check the resistance of the ground speed
solenoids L23 between connector X100 pins A & B (rev) and connector X100 pins C & D (fwd). The proper
resistance range for the ground speed solenoid is 16 - 20 K ohms.
A. If out of specification, replace the solenoid.
B. If the coil is within specification, continue with Step 3.
3. Use a multimeter to check continuity between connector X100 pins B & C and chassis ground. There should
be approximately 50 ohms resistance measured on each pin.
A. If there is continuity on connector X100 pin B, but not pin C, there is an open in the gearbox (GB) harness
between connector X100 pin C and the harness splice wire 887 blue. Locate the open and repair.
B. If there is continuity on connector X100 pin C, but not pin B, there is an open in the gearbox (GB) harness
between connector X100 pin B and the harness splice wire 886 blue. Locate the open and repair.
C. If there is no continuity on either pin, continue with step 4.
4. Disconnect connector X011. Use a multimeter to check continuity between connector X011 pin G and chassis
ground. There should be approximately 50 ohms resistance.
A. If there is continuity, there is an open in the gearbox (GB) harness wire between the harness splice and
connector X011 pin G wire 881 blue. Locate the short and repair.
B. If there is no continuity, continue with step 5.
POWER TRAIN - TRANSMISSION Hydrostatic
2 4/7/2006
C.20.F / 96