blue thunder

I am having no luck figuring out how to wire this new ignition box into my existing t-bolt IV ignition. I am using the wiring diagram for "point or electronic amplifier". Problem is, the original coil has 4 wires going to it. MSD instruction does not account for the termination of all 4 of these. The four wires existing are: two purple to the (+) side of the coil, two grayish to the (-) side of the coil. One of the purple wires is from the main harness plug (+12v switched I think) and the other goes to the t-bolt IV module. One of the gray wires comes from the t-bolt IV module, and the other goes to the main harness plug (tach signal I think).

So right now I have the one gray wire from the t-bolt as my trigger and is hooked to the white wire coming out of the MSD (per directions). The purple wire coming from the main plug is terminated to the red wire from the MSD (per instructions). The orange and black from the msd go to the + and - terminals on the coil (per instructions).

Thats it. No more instructions. But there are still 2 wires left unaccounted for. The purple from the existing t-bolt and the gray that goes to the main harness plug. No where can I find instruction on where these go. I tried putting the extra purple under the + side of the coil and the extra gray under the - side of the coil but got no spark.

If anyone out there can help me, it would be greatly appreciated!!! I am stumped

BT

Allan4

Does it run/spark as it is?

When I rigged my new motor and went with the 6AL I had a gray and purple wire that were left un used, so I just taped them up and zippy tied them out of the way. I left them in incase I put the old motor back in and go with the GM ign system again.

BTW, the gray leading from the harness is probably your main ignition wire and the purple is probably the tach

Hope this helps, first things first though, see if it will fire and if not be sure you are getting juice to the MSD box, then you can work your way thru the rest of it....

Good luck......

FindMe

All you need to do is get the harness adapter to hook your 2 magnetic pickup wires in your distributor to the green and purple wires at the MSD box, you do not need the Thunderbolt ign module. You will however need to add the MSD rev limiter if you want protection from out of water experiences. Your Tach will run from the tach signal terminal in the MSD box, and may require an adapter depending on equipment. The MSD website has the info on those, and the wiring hooks up like below...

MSD wire hookup
Power Leads

These are the two heavy gauge wires (12 gauge) and are responsible for getting direct battery voltage to the Ignition. Theignition has an internal fuse so no fuse is necessary.

Heavy Red

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 the alternator.

Heavy Black

This wire connects to a good ground, either at the battery negative (-) terminal or to the engine.

Red

Connects to a switched 12 volt source. Such as the ignition key or switch.

Orange

Connects to the positive (+) terminal of the coil. This is the only wire that makes electrical contact with the coil positive terminal.

Black

Connects to the negative (-) terminal of the coil. This is the only wire that makes electrical contact with the coil negative terminal.

Trigger Wires

There are two circuits that can be used to trigger the MSD Ignition; a Points circuit (White wire) and a Magnetic Pickup circuit (Violet and Green wires). The two circuits will never be used together.

White
(this should not apply to you)
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.

Violet and Green (Magnetic Pickup Connector)
(this should apply to you)
These wires are routed together in one harness to form 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. The Violet wire is positive (+) and the Green is negative (-). When these wires are used, the White wire is not.

It's a simple hookup using the Violet and Green wires to the pickup in your dist. Good luck

Call them & tell them what you have, and make it easy...

TECH LINE: (915) 855-7123
MSD TECH LINES are open Monday thru Friday from 8am to 5pm Mountain Standard Time.

blue thunder

I have no spark whatsoever. I double checked to make sure I had 12V going to the MSD. I had considered trying to eliminate the tbolt ignition, but do not understand if done so, what would control my advance curve. I purchased the MSD with the rev limiter included. I think it can be make to work with the points/amplifier scheme though...

Thanks for the help... keep the ideas flowing

BT

Mbam

Purple = ignition

Hook both the purples you took off the coil to the MSD small gauge red wire

Gray = tach

Hook both the gray wires you took off coil to the MSD white lead, or find which one comes from the Tbolt module and leave that hooked to the white and hook the other (it goes to the tach) to the MSD tach output.

HOOK NOTHING TO THE COIL except the orange and black ! I hope you did not fry the Tbolt module with te 400 volts the MSD sends to the coil !

The Tbolt distributor is a Hall Effect unit and requires a power source. You can use the mag pickup wires and eliminate the advance module, but that means locked advance with no curve. I don't really recommend it but it can be done.

BT we use the MSD with the TBolt all the time and it works fine.

blue thunder

Marc... you are reading my mind. I was worried I may have fried the t-bolt module as well with the 400 volts on the 12v input side of the module, so I hooked it back up stock and it started right up. Could it (the module) still be fried? Hope not.

Thanks for the guidance. I'll check back and let you all know how I made out.

BT

blue thunder

Update... Wired the unit like Mbam instructed and she came right to life this time. All seems good. Now to make a respectible job out of my rats nest.

Thanks for all the replies.

BT