Multi Pro 1750
Page 5 − 51
Electrical System
Relays with Four (4) Terminals
Your Multi Pro 1750 uses a number of electrical relays
that have four (4) terminals.
The main power relay is used to provide current to
most of the fuse protected circuits (InfoCenter dis-
play, spray system components, headlights and op-
tional electric equipment). The power relay is
energized when the ignition switch is in the RUN or
START position. This relay has four (4) terminals and
is located under the operator seat next to the fuse
blocks (Fig. 69). The main power relay can be identi-
fied by a tag at the relay wire harness connector.
If the machine is equipped with an optional electric
hose reel kit, an additional four (4) terminal relay is
added to the electrical system. The hose reel relay is
energized when the hose reel switch is pressed. The
hose reel relay is located in the power center com-
partment of the battery box.
Testing
1. Park machine on a level surface, stop spray pump,
stop engine and engage parking brake. Remove key
from ignition switch.
2. Raise operator seat and locate the desired relay. Dis-
connect wire harness connector from the relay and re-
move the relay from the machine.
3. The relay terminals are marked as shown (Fig. 70).
NOTE: Prior to taking small resistance readings with a
digital multimeter, short the meter test leads together.
The meter will display a small resistance value (usually
0.5 ohms or less). This resistance is due to the internal
resistance of the meter and test leads. Subtract this val-
ue from from the measured value of the component you
are testing.
4. Using a multimeter, verify that coil resistance be-
tween terminals 86 and 85 is approximately 72 ohms.
5. Connect multimeter (ohms setting) leads to relay ter-
minals 30 and 87. Ground terminal 86 and apply +12
VDC to terminal 85. The relay should make and break
continuity between terminals 30 and 87 as +12 VDC is
applied and removed from terminal 85.
6. Disconnect voltage and test leads from the relay ter-
minals. Replace relay if testing determines that the relay
is faulty.
1. Fuse blocks
2. Main power relay
3. Electric hose reel kit
relay (opt.)
Figure 69
1
2
3
Figure 70
86 87
85 30
85 86
87
30
7. If the relay tests correctly and a circuit problem still
exists, check wire harness (see Electrical Schematic
and Wire Harness Drawings in Chapter 10 − Electrical
Drawings in this manual).
8. Secure relay to mounting bracket and connect wire
harness connector to relay.
9. Lower and secure operator seat.
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