Service Manual

Multi Pro 5800Page 6 − 88Electrical System
Diode Assemblies
All Multi Pro 5800 machines include several diode as-
semblies (Fig. 129). The diode assemblies plug into the
vehicle wire harness at various locations (see Electrical
Schematic and Wire Harness Drawings in Chapter 11 −
Foldout Drawings).
The speed lock circuit includes two (2) diodes. One of
the diodes is used to provide a holding circuit for the
speed lock relay. The second diode is used for circuit
protection from voltage spikes that occur when the
speed lock coil is de−energized.
The spray boom lift circuit includes four (4) diodes for cir-
cuit logic. The diodes allow power to flow to the boom lift/
lower enable solenoid (S1) when either boom lift/lower
switch is set to the raise or lower position.
If the machine is equipped with an optional foam marker
kit, a series of six (6) diodes are used to protect the cir-
cuit from voltage spikes when the foam pump is ener-
gized or de−energized. The diodes plug into the optional
foam marker wiring harness.
If the machine is equipped with an optional homologa-
tion (road light) kit, three (3) diodes are used to control
turn signal/flasher circuit power. The diodes plug into the
optional homologation kit wiring harness.
Testing
1. Park machine on a level surface, stop engine and en-
gage parking brake. Remove key from ignition switch.
2. Locate diode assembly to be tested and remove
cable tie that secures diode to wire harness. Unplug the
diode from the wire harness for testing.
Multimeter
Red Lead (+)
on Terminal
Multimeter
Black Lead (−)
on Terminal
Continuity
Female Male YES
Male Female NO
Figure 128
Figure 129
1. Diode assembly
2. Male terminal
3. Female terminal
4. End of diode body
1
2
3
4
3. The diode can be individually tested using a digital
multimeter (diode test or ohms setting) and the table
provided (Fig. 128).
4. If testing determines that diode is faulty, replace
diode assembly.
5. If the diode tests correctly and a circuit problem still
exists, check wire harness (see Electrical Schematic
and Wire Harness Drawings in Appendix A − Foldout
Drawings in this manual).
6. After diode testing is complete, make sure that resis-
tor is fully seated into wire harness connector and se-
cured to the wire harness with a cable tie.