Installation of the MSD 6 Installation of the MSD 6 series Ignition Box on the series Ignition Box on the

1993 Ford Probe GT1993 Ford Probe GT

V0.2 BetaV0.2 BetaApril 22, 2000April 22, 2000By: Mike Paszti (paszti@home.com)By: Mike Paszti (paszti@home.com)Photography: George GebaraPhotography: George Gebara

Contents• External coil tower (the screw)• Transistor hook-up, and MSD box hook-up• Schematic• Miscellaneous notes

What You Will Need• MSD 6A series ignition box• MSD or other suitable external ignition coil• 3055 NPN transistor• 1k resistor (1/4W or greater)

External Coil TowerExternal Coil Tower

The external coil tower is a screw that is screwed into the distributor cap so as to allow the high voltage outputof an external coil to enter the distributor in order to bedistributed to the cylinders.

The screw is driven through the cap so that it contacts themetal strip embedded in the plastic. This strip is common with(i.e., electrically connected to) the rotor inside the cap.

Epoxy is used to reinforce the screw and provide a securefit for the plug wire boot.

External Coil TowerExternal Coil Tower

External Coil TowerExternal Coil Tower

Metal strip runs internally Metal strip runs internally along dashed linealong dashed line

Screw with shavedScrew with shaved

down headdown head

Epoxy Epoxy reinforcementreinforcement

My own repair (unrelated)My own repair (unrelated)

External Coil TowerExternal Coil Tower

Transistor Hook-upTransistor Hook-up

The transistor used in this project is a TIP3055 NPN transistor.It is readily available at Radio Shack for a few dollars.

The 3055 transistor is what triggers the MSD box to fire a spark.The transistor is triggered by the ECU.

By using the 3055, the internal ignitor module is completely bypassed.

Transistor Hook-upTransistor Hook-up

AA

BB

CC

ffeeaaccbbdd

cut

cut

cut

cut

cut

Ignore this diode. It is not required.Ignore this diode. It is not required.

ff

ee MSD

whi

te w

ire

MSD

whi

te w

ire

B, CB, C

Transistor Hook-upTransistor Hook-up

The following wires are cut at the distributor:- A- B- C- e- f

Connections to these wires are all made on the engine sideof the cut wire (not the distributor side).

Transistor Hook-upTransistor Hook-up

Connect to ‘e’: Connection to ground. The ground wire ‘e’ can be identified by its all black colour.

Connect to ‘B’(note 1k resistor): This is the tachometer signal

- MSD Box white wire- ‘A’: ECU requires this signal to operate

Connect to ‘f’: This is the trigger signal from the ECU. This wire will have a coloured stripe on it.

Connect to

MSD Box Hook-upMSD Box Hook-up

Thick Black Wire: Ground to frame

Thick Red Wire: To battery + or high current fused line

Thin Red Wire: Ignition switch (‘C’)

White Wire: Connect to middle lead on transistor

Orange Wire: To external coil “+”

Thin Black Wire: To external coil ‘-’

MSD 6AMSD 6A

SchematicSchematic

Thick Black Wire: Ground to frame

Thick Red Wire: To battery + or high current fused line

MSD 6AMSD 6A

+ -ExternalExternal

CoilCoilDistributorDistributor

CapCap

‘C’‘f’

1k resistor ‘B’

‘A’

‘e’

3055

Miscellaneous NotesMiscellaneous Notes

• Mazda/Ford made subtle changes to the distributor between model years. In some model years wires ‘A’ and ‘B’ are switched.

• As noted earlier, ‘e’ and ‘f’ are incorrectly identified in the Ford Service Manual. If in doubt, the ground wire ‘e’ can be identified by its all black colour.

• There appears to be some differences between the 1993 Probe GT tachometer electronics and those of the Mazda 626/MX-6. This writer was unsuccessful in making the tachometer work on a 1994 Mazda 626 with a MSD 6A BTM even though the exact same set-up worked on a 1993 Probe GT. The MSD tachometer adapter may resolve this problem.

•As noted earlier, regarding the wires that are cut at the distributor, all connections are made to the “engine” side of the wires.

• The cut connections on the distributor side, particularly ‘A’, ‘B’, and ‘C’, should be electrically insulated to prevent shorting.