New Holland CX720 Repair Manual page 1378

DO NOT use a self-powered test light for any of these tests. Use of a self-powered light can cause damage
to components in this system. M979
Before performing any of the electrical tests, be sure all operating controls are in neutral or park lock position.
This will eliminate accidental movement of the machine or start-up of power driven equipment. M980
N° Test Point
1 Place Ignition Switch in "ON" posi-
tion.
Close Work Light Switch.
Measure for 12 volts at Lower Work
Lights Relay (pin 5).
2 Measure for 12 volts at Lower Work
Lights Relay (pin 1).
3 Measure for 12 volts at Lower Work
Lights Relay (pin 3).
4 Disconnect the Lower Work Lights
Relay. Measure resistance on circuit
157 (BK) to Lower Work Lights Relay
(pin 2) and ground.
Work light Switch - Testing (A.40.A.30.83 - G.40.A.20)
NOTE: The batteries must be fully charged and all connections clean and tight. Use a multimeter (DVOM) or an
unpowered test light for these tests.
DISTRIBUTION SYSTEMS - LIGHTING SYSTEM
CAUTION
WARNING
Expected Result
12 volts.
If good reading, the relay is operating
properly.
12 volts.
If good reading, go to next test point.
12 volts.
If good reading, go to next test point.
Less than 1 ohm.
If good reading, replace Lower Work
Lights Relay.
2 4/7/2006
A.40.A / 62
Other Result (Possible Cause)
Lower Work Lights Relay.
Adjacent circuits.
Go to next test point.
Open or short to ground in circuit
187 (WH), 188 (WH), 189 (WH)
or 190(WH) between Lower Work
Lights Relay (pin 1) and CCM-1
(J1-11).
See Service Manual for testing of
CCM.
Open in circuit 64 (RD) between
Lower Work Lights Relay (pin 3) and
Fuse F-54.
Short to ground in circuit 65 (PU),
645 (PU), 644 (PU) or 646 (PU) be-
tween Lower Work Lights Relay (pin
3) and Lower Work Lights or Grain
Tank Light.
A short will cause the Fuse F-54 to
blow.
Open in circuit 157 (BK) to Lower
Work Lights Relay (pin 2) and
ground.