MAN# 650266
Relay Wiring Tips for Dakota Digital’s
RLY-1 RLY-2 and RLY-3
The purpose of this set of instructions is to explain and demonstrate a few general
relay wiring techniques. Relays can be used for numerous vehicle accessories and are not
limited to; window motors, door poppers, linear actuators, and solenoids. Relays can also
be used to supply power to fuel pumps, lights, fans, and other higher current loads. The
purpose of a relay is to switch a high current device with a low current source. This
eliminates the need to run large power wires to every switch on the dash.
A relay can switch up to 30 amps to the desired load, 70 amps with the RLY-3. A
small coil controls the switching function and draws less than 200 mA, hence a low
current switch for a high current load. A typical automotive relay has 5 connections on it,
see Figure 1. This is looking at the bottom side of the relay. All of the terminals are
numbered and starting at the bottom going around clockwise are: 30, 86, 87, 85 and 87a
in the middle. Connections can be made using female spade terminals or the supplied
socket with Dakota Digital relays.
87
86
87a
85
30
FIGURE 1 Typical Relay Connections
The tables below show the appropriate wire colors for Dakota Digital’s RLY-1,
RLY-2, and RLY-3 and the corresponding connection number.
RLY-1 RLY-2 RLY-3
Black
30
Purple
87(both relays)
Black
30
Red
86
Red
86(both relays)
Red
86
Green
87
Brown
87a(relay1)
Green
87
White
85
White
87a(relay2)
White
85
Blue
87a
Blue(large)
30(relay1)
Green(large)
30(relay2)
Blue(small)
85(relay1)
Green(small)
85(relay2)
*Note: RLY-3 function is identical to RLY-1 except there is no normally closed contact, 87a, and it can
handle up to 70 Amps
Pin 87 of the relay is the main power or the source for the load to be driven. Most
of the time the power wire to pin 87 is a larger gauge wire run direct from the battery
with an inline fuse for protection. Pin 30 is the “output” which delivers the power to the
load. The wire out of pin 30 is also a larger gauge wire supplying the appropriate amount
