WORKSHOP MANUAL
EDITION
PAGE
116 /
124
The table below indicates the functions of each relay, with reference to the colours of the wiring
cables.
87
85
30
86
87A
PTO relay: it intervenes if the conditions necessary to operate the work equip-
ment are not met during the work phase
87
85
30
86
87A
Safety relay: it intervenes if the necessary conditions are not met during the
work phase (operator presence)
87
85
30
87A
86
Only with Honda engines - Ignition safety relay: it intervenes as a safety device
if the conditions are not met during the ignition phase
A basic relay consists of a coil of wire wound around a soft iron (magnetic) core. When current is
passed through the coil, the core is magnetized and pulls down on a magnetic lever.
The lever in turn is attached to several switch contacts which open or close other electrical circuits.
In this fashion, a small current can control one or more larger electrical currents and actuate sev-
eral other devices.
In most cases a relay contact moves only a fraction of an inch and the magnetic pull is low.
To check the operation of a relay you must have an Ohmmeter-dependent tester.
Disconnect the relay and connect the tester tips to the various contacts of the component con-
cerned, an initial check with the relay disconnected and another with the power supply contacts
connected to an external 12 Volt battery.
The readings shall be as indicated in the table below, where the red continuous line indicates the
electrical continuity occurring inside.
PTO relay
Safety relay
Ignition safety relay (only with Honda
engines
Not powered
87
85
30
86
87A
87A-30 = 0
87-30 = ∞
Powered
87
85
30
86
87A
87A-30 = ∞
87-30 = 0
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