New Holland CX720 Repair Manual page 2552

E0179-04-LoP Isense Grnd Spd Hydro Shorted to Low Source
(C.20.F.91.11 - G.30.B.53)
E0179-04 - LoP Isense Grnd Spd Hydro Shorted to Low Source
Cause:
CCM2 has detected that the LoP Isense Grnd Spd Hydro circuit current is < 5 mA while the MFH is not in neutral,
and the combine is moving.
Possible failure modes:
1. The LoP Isense Grnd Spd Hydro wiring is shorted to ground.
2. CCM2 internal failure.
Solution:
1. The LoP Isense Grnd Spd Hydro circuit is the ground path for the Ground Speed Hydrostat solenoid circuit. By
monitoring the 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 a short circuit on the return line while the combine is moving.
Verify the fault is present. Enter the Infoview monitor - ""Diagnose info"" screen, "Driveline" sub menu. Select
"LoP Isense Grnd Spd Hydro" and observe the voltage with the MFH out of neutral, and the combine moving.
The normal operating range for the LoP Isense Grnd Spd Hydro circuit is 0.0 - 4.4 volts .
With the MFH in out of neutral, and the combine moving, the voltage indicated should be > 0.2 volts .
A. If the voltage reading is less than 0.2 volts , continue with Step 2.
B. If the voltage reading is within the proper limits, the shorted wire may be intermittent at this time. Continue
troubleshooting at Step 4.
2. Look for the shorted wire. Stop the combine and turn off the ignition switch. Disconnect the ground speed
solenoid connector X100 and CCM2 connector X017 . Using an ohmmeter, test for a short to ground on pin 35
wire 881 blue of connector X017 .
A. If the ohmmeter does not show continuity to ground, then the wiring from CCM2 connector X017 pin 35 to
connector X100 pins B and C is good. Continue troubleshooting circuits 879 and 880 from Ground Speed
Hydrostat L-23 with Step 3.
B. If the ohmmeter indicates continuity to ground, then inspect the wiring between Front Frame harness con-
nector X017 and connector X008 . Then inspect the wiring between Main Frame harness connector X008
and connector X011 . Next inspect the wiring between Gear Box harness connector X011 and connector
X100 . Locate and repair the short to ground. Continue to Step 4.
3. Look for the shorted wire in circuit 879 or 880. Using an ohmmeter, check for continuity to ground at connector
X100 pin A circuit 879 and then pin D circuit 880, with connector X017 disconnected.
A. If continuity to ground is found on pin A, locate the short in circuit 879 grey. If continuity to ground is found
on pin D, locate the short in circuit 880 grey. Inspect the wiring between Front Frame harness connector
X017 and connector X008 . Then inspect the wiring between Main Frame harness connector X008 and
connector X011 . Next inspect the wiring between Gear Box harness connector X011 and connector X100
. Locate and repair the short to ground. Continue with Step 4.
B. If no damage is found, replace CCM2. Continue with Step 4.
4. Visually inspect the harness and connectors for damage, bent or dislocated pins, broken or pinched wires. Re-
install all connectors and wiring disconnected during troubleshooting.
A. Repair any damage found during visual inspection.
B. If no damage is found, erase the fault code and continue operation.
Series 1348 and above
Wiring harness - Electrical schematic frame 09 (A.30.A.88-C.20.E.09)
POWER TRAIN - TRANSMISSION Hydrostatic
2 4/7/2006
C.20.F / 100