Wiring Question regarding 12V ignition

[countrypyhysician]

I have a US Shift Quick 4 control module to my 4R70W transmission on a 1974 Bronco. Ground is hooked directly to the battery. Power is run to a 12V igntion wire (peach) under the dash. In the on position, solenoid B constantly clicks and the transmission module buttons malfunctions. Once cranked it functions fine. Over 200 miles driving it. After talking to US shift, he thinks it is a problem in the ignition wire as I am only getting 11.2V (tested with a multimeter from the battery negative to this wire) from the ignition wire. It needs 12V. This is a picture from under the dash of the peach wire the mechanic used to tie in this pink wire for ignition power. Does anyone know what the peach wire's function is and why it is dropping voltage? Also, any suggestions for another wire to use for a 12V ignition power?

 

[EPB72]

that looks like the resistor wire that supplys power to the ignitionn coil.?

 

[DirtDonk]

Yeah, too bad they weren’t more careful on choosing wires.
They probably tested and found out that this connection was the only one on the back of the ignition switch that had power in both run and start positions.
But on that same connector is a green with red stripe wire. That would’ve been the one to cut and tap into.
It energizes the voltage regulator under the hood and should have 12v or close to it.
Whereas the pink/peach/puke brown wire that was spliced into is indeed the resistor wire.

Luckily you’re getting that higher voltage reading because it was spliced into near the ignition switch. If they had spliced into it under the hood or further up the line, you probably would only be getting 7 to 9 V.
But at least it’s powered in run and start.
Can you see the green with red stripe wire?

 

[countrypyhysician]

Yes I can. I am going to use the green with red. I also plan on changing to a 1 wire 3G alternator so I will no longer be using the voltage regulator. Will that be a problem using the green with red?

 

[DirtDonk]

Nope. On most Broncos prior to 76, energizing the regulator was literally it’s only function.
Once you’ve eliminated the external regulator, you will still want the wire under the hood to energize the internal regulator in the 3G.
So it will still have that function (unless you’re using a 1-wire version) but can easily share duties with computer power.