New Holland CX720 Repair Manual page 2803

Control valve - Electrical test (D.14.E.14 - F.40.A.50)
1. If the RWD system is not engaging, the solenoid (1)
on the E-T II valve may not be functioning properly
due to a faulty solenoid valve. Use the following pro-
cedure to test the solenoid valve:
2. Engage the parking brake. Have an assistant turn
the combine ignition switch to the "ON" position (DO
NOT start the combine) and move the RWD system
switch to the "ON" and "OFF" position several times.
Listen for an audible "click", indicating the solenoid is
shifting the main valve spool.
3. If the solenoid does not produce an audible "click",
check for loose wire connections at the screw ter-
minal or connector on the solenoid and at the RWD
switch inside the cab.
4. Check that the solenoid is properly grounded by the
E-T II valve. The solenoid is internally grounded
by the E-T II valve and can be tested by running a
jumper wire between the nut on end of the solenoid
and the combine frame. Make sure the jumper wire is
connected to bare metal. With the jumper connected
have the assistant turn the ignition switch to the "ON"
position (Do NOT start the combine) and move the
RWD switch to the "ON" and "OFF" position several
times.
TRAVELLING - 2WD-4WD SYSTEM Hydrostatic
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