INSTALLATION INSTRUCTIONS
AUTOTRONIC CONTROLS CORPORATION
• 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • (915) 857-5200 • FAX (915) 857-3344
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 tach output terminal
on the side 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.
Figure 8 Wiring the Dual Ballast Resistor
Figure 9 Installing the diode to a GM or Ford Vehicle.
Figure 10 Installing the Diode to a
1973-1983 GM Vehicle.
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 8.
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 9 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 9).
Ford: Install the Diode inline 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 10). It is usually a Brown wire.
