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Replace the ignition switch with one from autozone, now have power to the terminal with the bad wires. Used a small screwdriver and was able to remove the spade from the hard shell. Thinking I should cut the pink of the connector and get as much of the red/yellow as I can and splice a wire to it and run it through the firewall and use it to power the msd. Should I tee off of that and splice it into the green/red to the S terminal wire for the voltage regulator??
I agree with cutting out the pink wire, it really isn't needed anymore.
The photo you posted of the back side of your ingition switch... Well, the red/ yellow wire didn't look that bad... It looked like it was still usable. Going forward towards the slice. How do you feel about the splice? Leave it or replace it? The output of the splice is powering the voltage regulator "S" input and the throttle solenoid.
If you choose to replace this splice, you could add another wire here and run it through the firewall to the MSD box.
A lot of this is just personal choice. I would just power the key ON signal needed for the MSD box off the green wire going to the "S" connection on the voltage regulator... Because it's easier. But easier isn't always BETTER.
Running a new dedicated wire from the ignition switch isn't a bad idea, after all keeping the engine running should be a top priority. Also, as you already mentioned, you could use the new wire to power the throttle solenoid and the needed input on the voltage regulator "S".
Regarding the Spade connection you removed from the hard shell. Do a test fit on one of your spare ingition switches. Does it grab tight... or fall off easy? You may have to give it a little squeeze with some pliers. Maybe scrape it a little to have shinny metal showing.
In the big picture, you fixed the problem when you installed the AutoZone ingition switch. Just a few minor things to clean up and you can call it fixed.
Removed the cluster to make access easier and found a red / yellow wire disconnected for the butt connector and some sketchy connections. Repaired harness pic 3. Had the alternator harness untaped as well as the harness on the passenger apron to the solenoid. Stared the truck and check the battery and it was charging and actually saw the replacement amp gauge move. All is good right....
Taped back up the harness's and buttoned everything back up. Start the truck and it is not charging and if I wiggle the alternator harness the motor dies but starts right back up. Unrapped the alternator harness again and ohm'd it checks out good but still dies when wiggled.
Pic two
SOO this is what is inside one of those round rubber connectors, a four way splice.
Pic four
A not good spare alternator harness for reference
Got the wiring guru coming tomorrow will see what we find
Sounds like a bad connection. Pull on the wires and see if any pull out. Then solder the connections back and you will not have to worry about it again.
Thoughts....
It looks like you are still running the needed key ON voltage to the MSD box downstream of the original resistor wire.
I think losing this voltage might cause the engine to quit. For troubleshooting, you could run it straight to the battery positive, then wiggle the wires again.
Regarding the alternator not charging. Do you still have the needed key ON voltage to the "S" Connection on the voltage regulator?
If you decide to replace the 4 way splice in picture 2, you could add an extra wire and run it to the MSD box.
Had replaced the autozone voltage regulator as it seemed the spades were to small and the plug wiggled with an oem FORD one I had in my stash. The tech showed up and started diagnosing the truck, that cat had more high tech equipment than I could count as well as basic wire jumper with aligator clips. Verified that alternator harness was okay as well multiple other wires.
So what was it? The new FORD voltage regulator was bad, put on the autozone regulator pulled the pins out of the hard shell connector and tightened them a little and it is charging, didn't take him 25 minutes even the amp gauge is working, looking at the movement in it I don't think it ever worked. Ended up using the existing factory wiring as it was other than some repairs like to the ignition switch wiring repair.
As to the cause of all of this Tracey the tech felt it was caused by either a faulty alternator or a voltage regulator. HMMM he has been doing this kind of work for 45 years have to take stock in his diagnosis
Want to thank all who contributed to this thread helping this rookie get this thing running and I think this thread will help others in the future. You guys are great
Thank you and for posting the pics for me. Also my tech said it would not needed to put a fuse in the MSD wiring as it draws very little juice and would no help any.
My thoughts were if it had an inline fuse, and there was a catastrophic failure within the box, like you had, it would keep the rest of the harness from burning up like yours did.
The tech explained that the juice from the box upon failure would mainly feed back through the main power feed wire as well as the ground and very little would back feed through the 16ga MSD box power wire. I agree with the idea of a fuse install but he didn't see the purpose. If you figure a good way to do it, let me know.
Again his thoughts on the failure were the alternator and the voltage regulator. He wanted to check out the old alternator but I had already turned in the core. The voltage regulator was inconclusive.
You know I have replaced alternators in the past that went bad but have never seen this kind of damage. I'm still thinking it was the MSD box as the cause and not the alternator but I try to listen to someone with more knowledge and experience than myself.
So when I get the amp / volt gauge conversion back, I am supposed to terminate the red and yellow wires out of the three wire plug ? Correct?
You know I have replaced alternators in the past that went bad but have never seen this kind of damage. I'm still thinking it was the MSD box as the cause and not the alternator but I try to listen to someone with more knowledge and experience than myself.
So when I get the amp / volt gauge conversion back, I am supposed to terminate the red and yellow wires out of the three wire plug ? Correct?
When the MSD box shorted internally, the alternator tried to send max current to the battery, until the engine quit. The alternator might have died during the process.
I also would have like to look at the failed alternator, to see if it was a normal failure, like worn brushes.... Or did the diodes Short out during the current surge.
If your AMP Meter is working now, as it should, are you still going to install the volt meter?
As an AMP Meter test, engine off, pull ON the headlights. Can you see the AMP Meter needle move to discharge? Switching to Bright Headlights, does it move farther?
Add the brake pedal... any change?
The question really is ... would you notice the slight needle movement while driving?
If you do install the volt meter, the red and yellow wires out of the 3 wire plug would then feed the voltmeter.
Jim
Edit: post 43 has information on wiring the Voltmeter.
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Last edited by JimsRebel; Dec 9, 2025 at 11:13 AM.
So when I get the amp / volt gauge conversion back, I am supposed to terminate the red and yellow wires out of the three wire plug ? Correct?
'
The 3-wire plug under the hood is what you're talking about. Correct?
If so, then it really depends on how you're going to connect the volt-meter in the dash.
There really is no need to do anything under the hood at that point. Yes, the two wires are now useless for sensing current flow. Just extra fluff under the hood, but they're not in danger of causing any trouble unless the rest of the wiring is suspect as well.
But since some of that wiring has been suspect from the very beginning, if I'm remembering that far back(?), then yes, you can cut them off somewhere and protect the ends from shorting out on anything. After all, they're still connected to the other power wires at some point in the harness. Meaning that they have a constant 12v on them at all times.
If you are replacing the main charge wire, and/or the main power feed wire to the cab, then the point is moot as the new wires will not have the two smaller Red/Yellow wires attached.
I think the previous comment about "using them for the volt-meter" was regarding the two wires up inside the dash harness, at the cluster. But I would not necessarily do that, unless you DO in fact cut at least one of the wires out of the loop under the hood.
That's because, if they remain intact under the hood, then they are both powered constantly with 12v. Which is not how you connect a volt-meter.
If you do disconnect/cut them under the hood, then you can utilize their other ends at the cluster, to power the new voltmeter. But you have to wire them accordingly, by connecting one to 12v power, and the other to a ground.
If you leave them intact and use one end to power the volt-meter, then the gauge will be active at all times. If the truck sits for long periods, this parasitic drain, as small as it might be, will eventually drain the battery.
Might take weeks or months, but not sure about that. I know radio clocks are going 24/7 and take a very long time to drain a battery. I'm just guessing, but I would think a volt-meter is only taking a little bit more than clock memory does.
The factory wiring for the other gauges, should be powered up through the IVR via (for some trucks) a Black w/green stripe wire. I'd have to look at the diagrams again to see what color they are for your year truck, but that would be "switched" power and, to my mind at least, more suitable for a voltage gauge install.
Sorry to confuzzle things more, but the comments about using the old wires to power a volt-meter I felt needed some extra discussion time and more detail.
It's just that, with the old wires, there is no positive and negative side. For the ammeter, they are both positive.
Yes the amp gauges moves slightly when the headlights are turned on so it is working. Rocketmans volt gauge install instructions say you have to have a switched 12v to one side and a ground on the other side, he also says to scratch out the printed circuit were it powers the old amp gauge. Sounds like a lot of drama to me and seeing as I never really paid any mind to that amp gauge in the 47 years I've owned this truck thinking just gonna leave it as it is and just drive it . Thanks again
I carry a Voltmeter meter that plugs into the cigarette lighter. Most of these also have charge ports for phones. Personally I like the larger digital display, due to tired old eyes. These are about $10.
Still time to get it on the Christmas gift list.
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https://a.co/d/i84nbh4
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Jim
Last edited by JimsRebel; Dec 10, 2025 at 06:26 PM.
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