MSD 7805 8-Plus Ignition Control Installation - Manual (Page 3)

INSTALLATION INSTRUCTIONS 3
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WIRING
GENERAL WIRING INFORMATION
Wire Length: All of the wires of the MSD Ignition may be shortened as
long as quality connectors are used or soldered in place. To lengthen the
wires, use one size bigger gauge wire (10 gauge for the power leads and
16 gauge for the other wires) with the proper connections. All connections
must be soldered and sealed.
Grounds: A poor ground connection can cause many frustrating problems.
When a wire is specified to go to ground, it should be connected to the
battery negative terminal, engine block or chassis. There should always
be a ground strap between the engine and the chassis. Always securely
connect the ground wire to a clean, paint free metal surface.
The MSD-8 Plus has a ground stud just to the left of the terminal strip. Use this to ground other MSD
accessories (Figure 3).
Coil Connections: When using a single coil, both coil positive terminals must be connected to the
coil. Either connect both orange wires to the coil, or use the supplied jumper to connect the two coil
positive termianls at the terminal strip.
Terminal Wire Function
ORANGE Connects to the positive (+) terminal of the second coil.This is the only
wire that makes electrical contact with the coil positive terminal.
COIL 2 +
BLACK Connects to the negative (-) terminal of the second coil. This is the only
wire that makes electrical contact with the coil negative terminal.
COIL 2-
HEAVY
BLACK
This wire connects to a good ground, either at the battery negative (-) terminal
or to the engine.
BAT -
HEAVY
RED
GRAY
BAT +
TACH TACH
2-STEP
IGNITION Connects to a switched 12 volt source. Such as the ignition key or switch. RED
WHITE
This wire is used to connect to the points, electronic ignition amplifier output
or to the Yellow wire of an MSD Timing Accessory.
When this wire is used,
the Magnetic Pickup connector is not used.
POINTS
VIOLET MAG +
GREEN MAG -
DARK
BLUE
This wire connects directly to the battery positive (+) terminal or to a positive
battery junction or the positive side of the starter solenoid.
Note: Never
connect to the alternator.
This terminal delivers a 12 volt square wave signal as an output for a
tachometer or devices that require an rpm signal.
When this terminal is connected to 12 volts, RPM module 1 is active. When
there is no 12 volts, RPM module 2 is active.
These wires are routed together in one harness from the Magnetic Pickup
connector. The connector plugs directly into an MSD Distributor or Crank
Trigger. It will also connect to factory magnetic pickups or other aftermarket
pickups (Figure 4). The Violet wire is pos. (+) and the Green is neg. (-).
When these wires are used, the Points Terminal is not.
ORANGE COIL 1 +
BLACK COIL 1-
Connects to the positive (+) terminal of the coil. This is the only wire that
makes electrical contact with the coil positive terminal.
Connects to the negative (-) terminal of the coil. This is the only wire that
makes electrical contact with the coil negative terminal.
GROUND
Figure 3 Ground Stud.