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Discussion Starter #1
I am getting ready to install EFI in my 68. I am using an EEC-IV and wiring harness from a 90 Mustang (auto). I have found a lot of info on wiring the various sensors and actuators to the ECU. Those same schematics show there are certain connections that need to be made to a "hot in run", "hot in start/crank", or "hot in run & start" circuit.

From a previous Duraspark conversion, I seem to remember the "S" and "I" terminals on the starter solenoid are "hot in start". Is this correct?

I also seem to remember there is a pink resistor wire that comes off of the ignition switch that is "hot in run & start". Can someone confirm this? (My car is apart, and I cant test the wires to see which one is "hot in run & start".) My plan is to run this to a supplemental fuse box to power my EEC relay, electric fan, and possible fuel pumps.

Lastly, are any wires coming off the ignition switch that are "hot in run" only? I want to use this to feed a supplemental fuse box to power the o2 sensors, part of the TFI ignition module, and a check engine light.

Thanks in advance

Thanks
Jon
 

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Hey, Jon. Yes, S and I terminals are hot in START only, but I would only use the I terminal to avoid overloading the key switch from the S terminal.

The PINK wire is originally to the ignition coil, and is a resistor wire. if you are only going to use it to trip a relay or two, that's fine. If it's for more than that, then take the power feed from before the PINK wire so voltage does not drop through the resistance. The stock electrical system should only signal relays - do not attempt to actually power anything from it. That can become less reliable very quickly.

Do not run "hot in RUN only" connections. Especially the TFI should be hot in START and RUN on the TFI POWER terminal, or you will not get spark during start. You also want hot in START only on the TFI START terminal so the EEC SPOUT signal (timing) is ignored, the PIP signal is used to fire the coil at default retarded cranking timing, and the coil dwell is RPM-based and controlled by the TFI instead of the EEC. When the key is released to RUN, all the ignition functions return to normal. HTH

David
 

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Discussion Starter #3
David,

Your post helps a lot. I am using the diagram by TMoss at veryuseful.com. I interpreted the TFI wiring as one lead goes to "hot in start" and one lead goes to "hot in run". Based on what you're saying, the "hot in run" lead should be "hot in run and start".

I was originally thinking of using the pink resistor wire for power, but then I decided on running it to relays. I will still pull the 12V from before the resistor, just to make sure there is enough voltage to operate the relays.

So that pink wire (or circuit, for that matter) is connected to the keyed ignition switch? I should be able to follow each of the wires that come off of the keyed switch until I find a pink resistor wire?

Thanks again for all your help.
 

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Based on what you're saying, the "hot in run" lead should be "hot in run and start".
Yes - at least for the TFI. The O2 sensors and CEL don't care, so you can run them off the same relay feed.
I was originally thinking of using the pink resistor wire for power, but then I decided on running it to relays. I will still pull the 12V from before the resistor, just to make sure there is enough voltage to operate the relays.
While the pink wire will trip a relay or two reliably, it certainly won't hurt to source it before the PNK wire. Go for it.
So that pink wire (or circuit, for that matter) is connected to the keyed ignition switch? I should be able to follow each of the wires that come off of the keyed switch until I find a pink resistor wire?
Right. The PNK wire is RED/LT GRN at the switch on most cars, but some models run PNK all the way to the switch.
:tup:
David
 

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Discussion Starter #5
Just got out to the garage today and found the "hot in run and start" wire at the ignition. I had the pink resistor wire all the way to the connector AND a red/yellow wire going to the same pin on the connector.

"Hot in Run and Start" is circled in red. I verified this by installing a batt., hooking up the ignition switch, and turning the key.

I took the pin out of the connector. I cut away about 1/4" of the factory wiring to expose non-corroded wiring. I then opened up the stock crimp style connector, twisted the two stock wires and the white wire together, then soldered everything together. I finished it off with heat shrink.


The white wire runs to a relay which powers a fuse buss. It will give me 6 circuits.

One thing down, 499,999 to go. Thanks for the help PSIG!!!
 

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The white wire runs to a relay which powers a fuse buss. It will give me 6 circuits.

One thing down, 499,999 to go. Thanks for the help PSIG!!!
No problem - just look at my signature line, right? So, it sounds like you're using the basic 'Stang harness, and simply providing the power feeds and relay systems the original chassis had - yes? This link has layouts of a similar concept (different EFI system) I did with my Merc. It that generally how you're going about it?

David
 

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Discussion Starter #7
The mustang has a relay for the EEC and a relay for the fuel pump already wired into the harness. I need to ground the EEC, ground the EEC relay, and run a constant 12V from the battery to both relays and they should be ready to go. The other relay is attached to the keyed 12V source and is for the electric fans, o2 sensors, and the TFI POWER terminal. The TFI START terminal will be wired to the "I" terminal on the starter solenoid.

As far as using the Mustang harness and wiring the EEC, I'm using TMoss' schematic for the 88-91 models.

The EEC relay is connected to constant battery voltage, as is the FP relay. The EEC relay energizes the VPWR, which sends a dead nuts 12.0 volts to the fuel injectors, inertia switch and FP relay and the MAF sensor.

The VPWR energizes the PF relay, which sends battery voltage to the fuel pumps. Hopefully I can get by without cutting into the factory harness, but I will add length if I need to.
 
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