Owners manual

10 INSTALLATION INSTRUCTIONS
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ENGINE RUN-ON
If your engine continues to run even when the ignition is
turned Off you are experiencing engine Run-On. This usually
only occurs on older vehicles with an external voltage
regulator. Because the MSD receives power directly from
the battery, it does not require much current to keep the unit
energized. If you are experiencing run-on, it is due to a small
amount of voltage going through the charging lamp indicator
and feeding the small Red wire even if the key is turned off.
Early Ford and GM: To solve the Run-On problem, a Diode is supplied with the MSD in the parts bag.
By installing this Diode in-line of the wire that goes to the Charging indicator, the voltage is kept from
entering the MSD. Figure 8 shows the proper installation for early Ford and GM vehicles.
Note: Diodes are used to allow voltage to flow only one way. Make
sure the Diode is installed facing the proper direction ( as shown
in Figure 8 ).
Ford: Install the Diode in-line to the wire going to the “1” terminal.
GM: Install the Diode in-line to the wire going to terminal #4.
GM: 1973 - 1983 with Delcotron Alternators.
GM: Delcotron Alternators use an internal voltage regulator. Install
the Diode in-line on the smallest wire exiting the alternator (Figure
9). It is usually a Brown wire.
MISSES AND INTERMITTENT PROBLEM
Experience at the races has shown that if your engine is experiencing
a miss or hesitation at higher rpm, it is usually not directly ignition.
1A-100V DIODE
FORD VEHICLES
ATTACH DIODE TO TERMINAL "1"
EARLY GM VEHICLES
ATTACH DIODE TO TERMINAL "4"
TO
CHARGING
LIGHT
SPLICE HERE
1 2 3 4
Figure 8 Installing the diode to a GM or Ford Vehicle.
NO-RUN ON FOREIGN VEHICLES
Some foreign vehicles with fuel injection systems may require an MSD Tach/Fuel Injection Adapter
to run with an MSD 6 Series Ignition. This is because many of these systems use the same trigger
source to operate the MSD, the tachometer and the fuel injection. This results in a voltage signal
that is too low to accurately trigger the fuel injection. To fix this, an MSD Tach Adapter, PN 8910, will
remedy the problem on the majority of vehicles. If the PN 8910 does not fix the problem, the PN
8910-EIS will be required.
Note: Toyotas and Ford Probes will require the PN 8910-EIS Adapter.
INOPERATIVE TACHOMETERS
If your tachometer fails to operate with the MSD installed you may need an MSD Tach Adapter. Before
getting an Adapter, try connecting your tachometer trigger wire to the Gray tach wire of the MSD. This
output produces a 12 volt, square wave (see page 2). If the tach still does not operate, you will need
a Tach Adapter. There are two Tach Adapters:
PN 8920: If you are using the Magnetic Pickup connector (Green and Violet wires) to trigger the MSD,
you will need the PN 8920.
PN 8910: If your tachometer was triggered from the coil negative terminal (voltage trigger) and you
are using the White wire to trigger the MSD you will need
the PN 8910.
BALLAST RESISTOR
If you have a current trigger tach (originally coil positive)
and use the White wire of the MSD, you can purchase a
Chrysler Dual Ballast Resistor (used from 1973 - 1976)
and wire it as shown in Figure 7.
Figure 7 Wiring the Dual Ballast Resistor.
SMALLER OF THE 2-WIRES
DIODE
WIRE LOOM
GM 2-WIRE ALTERNATORS
Figure 9 Installing the Diode to a
1973-1983 GM Vehicle.