Midlife

If the rest of the car is stock, then the alternator will work just fine with the existing wiring. Ford built in a safety factor of about 2 for wiring and currents. The alternator supplies a level of current that is demanded by the various components. If everything is pretty much stock, the alternator will put out a fraction of its available output to the car for running and charging the battery. Overloading the existing wiring happens when you add a load (not a source) of current such as electric fans, a thumper stereo, halogen headlights, etc.

C85(?)A is a full size ford designation. Although the prefix comes from which model line designed the TSSwitch, that re-inforces the idea that this switch is for other models as well. Just because it has a Ford part number on your TSS does not mean it was original to your car.

I believe what jagbucket is experiencing is that the reproduction turn signal switches are generic Ford models, ones that fit a variety of Blue Oval models. With 11 wires and only 10 possible pins on the turn signal switch connector, something is definitely out-of-whack. There's nothing in the turn signal switch itself that would interrupt the car being started.

PRNDL lamp uses an extension from the blue/red female bullet (or three prong plug if 1970). I may have one of the PRDNL lamp extensions/harnesses in my big plastic box of miscellaneous stuff.

What is listed in the YandZ catalog looks no different from Alloy Metal's products. I'm willing to bet they are simply retailers and not manufacturers.

My reasoning was that wiring exposed to the heat and elements for 40+ years won't hold up as well as that inside the car itself. With time, that's proved to be somewhat inaccurate, as most headlight harnesses can be refurbished satisfactorily. For earlier years, where the cost of reproductions are more reasonable, I do steer customers towards repro's, but the 69 and up are more expensive and refurbishment is a good alternative.

I can refurbish the headlight harness, reducing your estimated costs a bit. My cost for a headlight harness is $75 with core.

Is the order of the spark plug wires correct for your engine/cam?

Front driver's side is 20 inches from break-out to bulb-side of connector.

Have you changed the water pump very recently? If the bolts are put in the wrong place, they interfere with the fuel pump resembling a 5 mile drive. Otherwise, you might have a bad coil. Two simple ideas...

Yeah, from what I can tell about how the VR works, the green/red wire is only hot when the key is in the RUN position, so I believe it acts as a stimulator for the VR/alternator to do their thing.

The other yellow wire from the voltage regulator is tied into the main battery power line within the harness.

Your #6 is for brake warning light power Your #8 is ammeter Your #9 is ammeter Your #10 is high beams Your #14 is CVR input power. Your 8-14 may be CVR input power, dash lamps, RH turn signal, and one ammeter line as there's no indication as to where the numbering starts. There are actual pin numbers on the connector. Dash lamps are truly #12.

I can provide the underdash harness if you only find the dash cluster. PM me if needed.

It's probably the turn signal switch, as they are notoriously known for going bad. But first, I would go around the four corners examining the ground wires to the rear lamps, the bulbs themselves, and fidget with the wires before tearing apart the steering wheel.

It's always wise to check to see if it is truly overheating instead of going just by the gauge. Have you used an infrared sensor ((~$45-$70) to determine the true water temperature? It could be as simple as your sending unit is for a idiot light instead of a gauge. Just trying to make sure you take care of the obvious first...

Can only use one electrically-based sending unit per gauge (you can get away with it with mechanical gauges). Ganging up on gauges will change the circuit's resistance. If autometer provides their own sending units, you have to use them.

There is a substantial difference between a 69 and a 70. The 70 has a long section beyond the firewall whereas the 69 ends up in 3 major plugs just past the firewall. The two harnesses are not interchangeable; you would be better off determining the year and revising your for-sale ad.

I think Max was confused, since the primary focus of the OP's post was the use of a vacuum gauge for tuning. Maleah did mention electrical issues as well. I'd be happy to help out if that is what is wanted. It takes only 2 weeks or so from pulling to re-installing the wiring. My website is http://midlife66.com/harnesses And thanks for the kind words!

Yes, it could be the IVR, but it could also be the resistor wire that feeds the input power to the IVR. Whenever I refurbish an underdash harness, I've found that this particular pin needs to be recrimped, as the initial resistance is much higher than the nominal 10 ohms. This wire is nichrome: a single strand that needs another standard wire to make the crimp good enough to make a connection at the pin. Often times, though, the crimp relaxes and resistance rises, reducing the voltage to the IVR.

I did not know that anyone made an ignition switch w/pigtail that included a resistor wire, but it is possible. I don't bother to check the catalogs for them; I harvest them from existing OEM harnesses. Yes, you can use a full length resistor wire version: simply splice it where convenient, keeping the overall length approximately the same. Total resistance should be 1.3 to 1.7 ohms. If your original does not use it, simply cut the pink resistor wire off and shield the tip from inadvertent contact to ground. Splicing the pink resistor wire can only be accomplished by a crimp or silver soldering. I recommend crimping. The key to installing an ignition switch w/pigtails is to match up the wires using colors. Most aftermarket switches also include a white/red wire on one socket that is not used on Mustangs. For a standard dash, the pink resistor wire at the ignition switch also shares that pin with a green/red wire. Simply match up each wire to its underdash harness counterpart and you should be good to go. If uncomfortable doing so, simply send the underdash harness to me and I'll refurbish the entire thing with OEM components and provide a 2 year, no questions asked warranty.

The pigtail for the ignition that has the pink resistor wire is for the standard, non-tach dash. The one without the pigtail is for the tach-dash configuration.

I believe like the 67/68's, there was a separate harness that plugged into the headlight extension plugs and ran all the way back to the headlight junction near the firewall. From there, another harness actually ran up to the hood turn signal lamps.

Good job! The heater hot wire is only hot on the RUN and ACC positions of the ignition. The A/C and non-A/C pigtails are the same, but the A/C version has another wire for the A/C controls. There is no brown wire, IIRC. The blue, red, and black/green wires are the ones that control the speeds; the switch diverts the 12V from the yellow wire to these wires (one at a time) and the other end goes through a resistor box, and then out to the blower motor. And yes, the system is grounded at the heater blower itself.

Essentially correct, in that the factory amp gauge measures the current flow through a secondary circuit of main power. This secondary circuit is based upon a different amount of resistance along the main power feed from the battery/starter solenoid/alternator position and somewhat further downstream towards the ignition switch. Current can flow through both systems, but the secondary system has just a bit higher resistance (maybe 0.1 ohms difference) due to the use of thinner wires. It doesn't take much corrosion, age, or bad contacts to render the difference insignificant, thus making the ammeter unresponsive. I have seen ammeters respond quite nicely to charging currents, but it is a rare sight.