ELECTRICAL SYSTEM
10I-29
SECTION 10I. RELAYS AND SOLENOIDS
RELAYS
Relays are electromechanical devices used to control
the transmission of electrical current with a circuit. A
schematic of the internal movement of the relay is
printed on the relay itself. The relays used in the
LF-1880 electrical system all use the same NO (nor-
mally closed) configuration.
Figure 10I-1. Relay Circuit
Pole 85, as shown in Figure 10I-1, is a grounded termi-
nal. When current is applied to pole 86, the coil circuit
between the poles is completed and a magnetic action
draws the switch lever at pole 87A to pole 87 closing
the relay and allowing current to flow from pole 30 (the
input power source) to pole 87 (the output power con-
nection).
RELAY TEST
The relays can be checked for proper operation as fol-
lows:
1. Remove the relay from the relay box
(Figure 10I-2).
2. Set the multimeter to the continuity scale.
3. Place one test lead on pole 30 and one test lead
on pole 87A.
Continuity should be available between poles 30
and 87A.
4. Using a 12-volt DC power source apply the
ground side to pole 85 and 12 VDC to pole 86. At
the same time check for continuity between poles
30 and 87.
There should be an audible “click” when current is
applied and continuity should be available
between poles 30 and 87.
NOTE:
If the relay responds as described in the above
test, the circuit problem may be in the power sup-
ply to the relay. Using the electrical schematics in
Section 10Q and a multimeter, check the relay
pole circuits.
Replace a relay that does meet the above test
results.
Figure 10I-2. Relays
30
85
86
87
87A
K6
Gy/Wh
Gy/Rd
DB/Wh
Bk
86
Relay Box
Relay Circuit
87
87A
85
30
Electrical Schematic
Symbol Designation “K”
10I
To Next Page
Loading...
Need help?
General
