anyone know how ignitions work?

Discussion in 'Fox 5.0 Mustang Tech' started by OonDeanisS, Jan 9, 2007.

  1. So now that i dont have the TFI, where should that power come from? because i wonder would it be correct to attach the red/blue wire to the red/grn and then both of them to the small red wire on the 6al?
  2. if you havent been to this site yet, check it out.

    about 3/4's of the way down the page it shows how to wire the chassis wires to your msd. you might have to cross reference with another diagram to make sure your wires match the same colors as that site shows. they may be a different color.
  3. what it says is to attach the small red wire from the 6al to the red/lt grn wire. Is that wired into the start circuit?
  4. from what the diagram shows on msd's site the red/lt green wire on the tfi's harness goes to the smaller red wire on your msd box. do you still have the factory wiring for the tfi coil on the car?
  5. i dont think so, but maybe. what would it look like?
  6. i have never had to press the clutch, and i dont remember seeing the red/blue or red/grn wires in the engine bay.
  7. so what does the tfi harness do? does it connect the red/blue to the red/grn?
  8. i'd hook your small red wire from the msd box to the red/lt green wire on the firewall harness and see if it starts in key run.
  9. the red/lt green wire on the tfi harness is for the hot in start cycle.
  10. what firewall harness? and i dont have a red/blue on my starter solenoid, just the thich green one on one side.
  11. let me go take a pic of my engine bay so you can find the tfi harness lol.
  12. alright heres the tfi coil harness
    View attachment 408383

    heres the red/blue wire on the starter relay, its right under the red cable for the battery post
    View attachment 408385

    heres the harness connectors that i was talking about, sorry, thought they were on the firewall but is near the strut tower. the gray harness has the red/lt green wire in it.
    View attachment 408387

    hope this kinda helps out some:shrug:
  13. think i got it figured out for you. under the dash on the ignition switch harness on the steering column, hook your small red wire from your msd box to the white/pink wire on that harness. now, run a wire from your positive side of the coil to the red/lt green wire on the ignition switch harness as well.

    that white/pink wire turns into the red/blue wire thats supposed to go on the starter relay. that is your "hot in run" cycle wire.
    that should get it to start, i'd hope.
  14. I can't undestand why you won't wire it up the way the MSD diagram shows. MSD designed the box, so they should know how to make it work.


    Your current dilemma is exactly why I am so critical of carb conversions. The road kill quality work someone else did now needs to be fixed so that the car can be driven.
  15. jrichker, its not that i dont want to, i just dont have the tfi harness, so you're suggesting i just hook the small red to the red/lt grn?
  16. The picture given of the tfi harness is wrong. That's the ignition coil harness, not the tfi harness. The tfi harness goes to the distributor and has 6 or more wires to it. You don't need the tfi harness, you need the coil harness.
  17. oh, sorry but there is the red/blue wire on my starter relay.
  18. YEs because red/blue is hot in start. red/green is hot in run. Normally the tfi module provides the power to the coil when the key is in the start position. If you do not have a TFI module, you will not have this function, and thus you have your problem.

    What you need to do, is connect your coil to both red/blue and red/green wires.


    You also need to put a diode on each wire so that power from one isn't going to blackflow into the other circuit. Otherwise turning the key to ON will be like turning it to START and ON at the same time.