INSTALLATION INSTRUCTIONS

7

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 6). It is usually a Brown wire.

MISSES AND INTERMITTENT PROBLEMS

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 related. Most probable causes include a coil or plug wire failure,

arcing from the cap or boot plug to ground or spark ionization inside the cap. Several items to

inspect are:

•Alwaysinspecttheplugwiresatthecapandattheplugforatightconnectionandvisually

inspect for cuts, abrasions or burns.

•InspectthePrimaryCoilWireconnections.BecausetheMSDisaCapacitiveDischarge

ignition and it receives a direct 12 volt source from the battery, there will not be any voltage

at the Coil Positive (+) terminal even with the key turned On. During cranking or while

the engine is running, very high voltage will be present and no test equipment should be

connected.

•Makesurethatthebatteryisfullychargedandtheconnectionsarecleanandtight.Ifyou

are not running an alternator this is an imperative check. If the battery voltage falls below

10 volts during a race, the MSD output voltage will drop.

WARNING: Do not touch the coil terminals during cranking or while the engine is running.

•Istheenginerunningleanorexcessivelyrich?Inspectthesparkplugsandfuelsystem.

•Inspectallwiringconnectionsforcorrosionordamage.Remembertoalwaysuseproper

connections followed by soldering and seal the connections completely.

LED: The LED on the ignition will assist in troubleshooting. If the LED does not flash, there is no

current through the primary coil wires. This could be due to poor connections at the coil, the

coil itself or the ignition. Once you confirm that the trigger signal is working, try a different

coil. See page 8 to test for spark.

If everything checks positive, use the following procedure to test for spark. MSD also offers an

Ignition Tester, PN 8998. This tool allows you to check your complete ignition system while it is in the

car as well as the operation of rpm limits, activated switches and shift lights.

Figure 5 Installing the Diode to a GM or Ford Vehicle.

Figure 6 Installing the Diode to a 1973-1983 GM Vehicle.