MSD 8961 Installation
MSD RELAYS
PN 8961, Single-Pole, Double-Throw, 30 Amp/12 VDC
PN 8960, Double-Pole, Double-Throw, 30 Amp/12 VDC
MSD Relays will allow you to activate a variety of accessories that require high current. These are
ideal to tie in with an rpm activated switch to control a nitrous or air shifter solenoid.
The benefit of a relay is that it can be energized using a small amount of power (12V/1 Amp). This
moves the relay's armature so it can transfer a large amount of power (12V/30 Amp) to activate a
high current device.
• The PN 8960 will handle a 30 Amp load, on each side, with an input voltage of 12 volts.
• The PN 8961 Relay will handle a 30 Amp load and is ideal for multiple accessories.
Following is a short description of the operation of a relay. A variety of wiring schematics are also
included to help with your installation.
Relays are very simple devices and consist of four basic parts:
• A small coil (sometimes referred to as a bobbin or electromagnet)
• An armature
• A spring
• A set of electrical contacts
Figure 1 General Relay.
Relays consist of two separate and completely independent circuits; the Controller circuit and Switch
circuit. In Figure 1 the Controller circuit is on the bottom and it controls the power to the electromagnet.
When 12 volts are supplied through the switch, the coil is energized. When energized, it attracts the
armature of the Switch circut.
The Switch circuit consists of an armature, spring and contacts for the high current side. The armature
is a switch and will complete or open the high current circuit. When the coil of the relay is energized, it
attracts the armature from one electrical contact to another to complete the circuit. When the coil is not
energized the spring pulls (or pushes) the armature back and the high current circuit is opened.
M S D • W W W . M S D P E R FO R MA N C E . C O M • ( 91 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4
2 INSTALLATION INSTRUCTIONS
INSIDE
86
1
7
3 4
2
1 7 8 6
3 4 20
8
6
0
87 87A
87A
85
30
87 NO
NC C NO
NC
C
86
85
30
LOCATION OF PINS
MSD PN 8961 RELAY
MSD PN 8960 RELAY
NO - NORMALLY OPEN
NC - NORMALLY CLOSED
C - COMMON
Relays have a variety of specifications. A few things to consider include:
• Make sure the Relay can accept and handle the voltage and current required to activate the desired
circuit.
• The number of bobbins to use with different circuits (generally 1-2).
• The number of electrical contacts for the armature (generally 1-2).
• If the Relay is Normally Open (NO) or Normally Closed (NC).
RELAY APPLICATIONS
Here are some examples of how a Relay can be used in typical automotive applications.
M S D • W W W . M S D P E R FO R MA N C E . C O M • ( 91 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4
Figure 2 Inside the MSD Relays.
USING MSD RPM ACTIVATED SWITCH, PN 8950, AND
MSD RELAY, PN 8961, TO ACTIVATE A SOLENOID
RED
12 VOLTS
RELAY
RED
PN 8961
YELLOW COMPLETES THE
GROUND PATH OF THE CIRCUIT
GRAY
(NOT USED)
BLACK
TO
GROUND
R
RPM
ACTIVATED
SWITCH
PN 8950
AUTOTRONIC CONTROLS CORPORATION
AUTOTRONIC CONTROLS CORPORATION
1490 HENRY BRENNAN DR., EL PASO, TX. 79936
1490 HENERY BRENNAN DR., EL PASO TX 79936
TO
GROUND
NITROUS OR
AIR SHIFT
SOLENOID
30
85
87
86
87a
WHITE TO
MSD TACH
TERMINAL
OR COIL (-)
YELLOW
Figure 3 Connecting a Transmission Solenoid with an MSD RPM Activated Switch and PN 8961 Relay.
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