I am trying to get the wiring hooked up on my 73 project and figured I would hook up a battery and make sure things worked. I have removed regulator and harness associated with it and am running a single wire alternator. Wiring to rear of truck is not installed yet. I am also running an MSD box.

Question #1...I hooked the small red wire of the MSD box to the Batt side of coil figuring this was a switched wire. Right or wrong?

Question #2...When switch is in the "ON" position I have no juice anywhere(that I can tell) other than the wires coming from the starting solenoid(red with blue stripe and black with white stripe) on inner fender and going to the starter relay in the truck, which the red wire also continues on to the rear truck harness. So this tells me the fuseable links ont the inner fender are good.No juice at headlights,dome light or fuse panel either. Also it has nothing in the acces. position either.
Is this right????Does the ignition switch have to be in the cranking position to send electricity to the remainder of the vehicle???

Did removing the regulator harness cause the issue????

I checked operation of the nuetral safety switch but did not test for continuity. It was operational when restoration was begun but you know how that is.

 

(1) Assuming you have retained the factory wiring to the coil, then yes, it is switched (meaning it's hot in RUN and in this case, START), however, it's not a full 12 volts. When the key is in RUN, the coil is powered through a ballast resistor. Taking the coil primary winding resistance into account, the coil voltage is actually on the order of 7 to 9 volts when running. With that in mind, many ignition modules require a constant 12 volts when running. Check the instructions for your MSD box - if it needs 12 volts, then don't connect it to the coil (I would imagine this is the case).

(2) The RED/BLUE wire at the starter solenoid should only be hot when the key is in START. It should not be hot with the key in RUN. There are a couple other items related to the coil and ignition module that are hot in START. However, nothing else should be hot-in-START ONLY. This is because most power to the truck (excluding things that are hot at all times, like headlights, etc) is shut off during cranking, so as much current can be delivered to the starter as possible. The ignition is powered while cranking so that the motor can actually fire. However, if a circuit isn't already hot at all times, then it will be DEAD during cranking, which is the opposite of what you are asking here.

The headlights and dome light should be hot at all times, regardless of the position of the ignition switch. The headlights get power directly from the battery side of the solenoid and are protected by a circuit breaker internal to the headlight switch. The dome lights are downstream of the dome light switches, which themselves are sourced by a hot-at-all times fuse in the fuse panel. A fusible link is upstream of both of these. The fusible link is not meant to protect these circuits (as it's a heavier gauge), but if the fusible link is gone, then neither of these circuits will work. However, if you're getting power at some point in time at the starter solenoid cranking signal (RED/BLUE wire), then that would indicate the fusible link is still in one piece, since current must travel through the link and then back out the ignition switch to make it to the starter solenoid.

The regulator harness simply connects the alternator and regulator, and gets keyed power to the regulator. It should not affect accessory circuits in the truck's electrical system.

The headlights, dome lights, etc should work independently of the neutral safety switch (NSS). The NSS should only cut off power to the starter solenoid cranking signal.

Unfortunately it's not very practical to troubleshoot this kind of problem over the internet because of the scale. I would recommend getting a wiring diagram (Chilton's manual, AutoZone website, etc) and start tracing wires at the source, and following them forward until you lose power where you should instead have it.

Also, just a word of advice - if you're doing this much troubleshooting, I don't recommend having a battery connected as your power source. It's too easy to bypass the wiring harness' protection and smoke the harness. A car battery will source as much power as it can until the load burns up. The fusible links are not designed to protect some of the lighter gauge wiring in the truck, and it's all too easy to bypass the fuse panel accidentally. Instead, I recommend using a "brick" (13.8 V) power supply that is current limited or fused to do some of this testing, until you're comfortable with everything.

Hope this helps.

 

Tracing the wires from the Batt side of the solenoid is something that
I tried. There are 2 that have what I think are the fuseable links in line right at the solenoid. I traced these wires back into the dash to what I think is a relay(starter I assume) which is mounted to the bottom edge of the dash.
This is where the power ends. I get a reading on the in wire but nothing coming out. I suppose I could bypass the relay and see if the rest of the truck has power. There isn't even any juice at the fuse panel.

I guess the problem is that tracing the wires out of the starter relay is kinda tough as one of them(black is a dead end that is correct as i
verified it as original (spare truck). The other wire is brown and goes into the main harness behind the gage cluster.

You are correct..I need a wiring diagram bad.

I'm pretty sure I have a power supply in the basement and thanks for the great idea.

Does the starter relay allow power to pass through in "start" position only???

 

The terms "starter solenoid" and "starter relay" are the same thing. This is the cylinder that's mounted on the passenger side inner fender. It is what engages the starter when the key is turned to START. There is only one starter solenoid (or starter relay).

So you're saying that you trace the main power coming from the solenoid back into the dash and it goes into some kind of mystery device (which you're calling a starter relay) - it's not obvious to me what this is. If you can post a picture, that would be helpful. Without knowing what this is, I can't say what it should or should not be doing.

The starter solenoid only "makes" or "closes" when power is applied at the 'S' terminal. When this happens, a large slug and plate inside jump the battery to the starter, making the starter turn. So yes, the starter relay (solenoid) only closes (allows power to pass) in START. However, as I said, what you're finding in the dash and referring to as a starter relay is not the starter relay.

 

Picked up a Haynes today and naturally the diagrams are for 74 and up. Wire colors appear to be different than my 73. Am going to have to do some decipherin. Ill post a pic Saturday od the relay.

Thanks for your help.

 

So I added a cab to engine ground strap and also grounded the starter just for fun.

I thought for sure my lack of cab ground was the problem but it is not.

The part number on the relay is DS2B-14677-AA. Parts store could only tell me that it was a relay.$39.00

It is not on any diagram that I can find but parts store said it was used on many different trucks.

It is screwed to the lower edge of the dash and has a 3 prong plug that gets connected to it. It seems to me that the relay would always be hot as it is fed by the Black/white that comes diractly from the batt side if the solenoid, so I dont understand what it actually does. Why would the ign. switch need a relay between itself and the battery?

I still have no power anywhere in the cab other than the 2 wires coming from the batt terminal.

The MSD box would be downstream of this problem right?

 

The ignition switch doesn't need any sort of relay; it is a direct connect to the battery. It distributes power to various circuits based on the position of the key. There may be relays downstream of power that is passed on by the ignition switch, but none in between.

The only relay I can think of that might sound similar to what you are describing is the horn relay; because it will have hot-at-all-times running to it. The horn will sound anytime you press on the steering wheel, whether the truck is on or off. That's the only relay I can think of that should have hot-at-all-times running to it. There is a member named NumberDummy here that should be able to read that engineering number and figure out what it's specifically used for.

That's a shame that the Haynes book doesn't include wiring for the '73; if the book says it's for 73-79 pickups then I'd at least try and get my money back. I guess the other option would be the factory service manual. It seems like I've seen them on CD on eBay.

Anyways, since you're (we're) diagram-less for now, here are some tips: the fuse panel is set up as a "breakout box" or sorts. There are different "landings" that accept power, and distribute it to various fuses. For example, a heavy-gauge hot-at-all-times wire runs from the starter solenoid to one of the landings on the fuse panel. This landing feeds things that are always on, such as the cigarette lighter and courtesy lights. Another landing comes from the hot-in-RUN side of the ignition switch, which feeds items like the fan motor.

Really the only way to solve this problem, wiring diagram or not, is to trace continuity from the power source, all the way to the load. A wiring diagram is handy, but all it tells you are the colors, really. For example, when the key is turned all the way to START, the 'S' post of the solenoid needs to have power applied to it. This signal must come from the ignition switch since it is specific to hot-in-START. So you'd make sure that power is transfered from the battery post of the solenoid to the 'S' wire when the key is turned to START.

Wiring is tedious; I know. I'm back and forth in my garage today rebuilding a wiring harness for my Galaxie. Here's a recent picture of my progress:



Doesn't get much messier than that. Sorry to take it off topic; just saying I know your pain!

 

WEEEELLLL. Thankfully mine looks nothing like yours.

So I spent the entire day in the barn. Looking, testing and thinking. I thought there would have to be another source wire to the ign. switch so I started peeling apart the harness to trace the wire.Ended up reinstalling the Regulator harness and walla. We now have power in the cab. My SCS that is sitting outside complete but somewhat molested saved my @#$ again. I finally figured I would put everything back to stock and then worry about the fancies.
I do not have dash lights, horn relay clicks but no horn and the engine is new so I thought I would give it a bump annnddd nothing there either..
At least now I think I can just trace the ign. wire on the solenoid back into the cab and...wait that would be going to that relay. I have the parts number disc on the way so hopefully I can run that number to figure out what the relay does.
Also I bought a one wire Alt and thought it would be similar to the 3G upgrade(harness removal) but I'm going to have to figure out how to keep power in the cab and also run my Alt gage.

Man, this is some kinda fun. I really appreciate your input.

 

When you took out the regulator you probably disconnected the main power to the cab. It it is a 10 or 12 ga wire with a 16 ga fuseable link it is black with a yellow stripe. I am pretty sure it has a two terminal plug with a red and yellow wire which are your ammeter shunts. I took out the ammeter shunt and plug then ran a new 16 ga fuseable link with a ring terminal to the black with yellow stripe wire. Just connect that to the bat side of your solenoid and you should be in business.