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A Few Electrical Questions - 1972 Plymouth

1921 Views 12 Replies 6 Participants Last post by  Grouch
As mentioned in another thread, I'm fixing up a '72 Plymouth Fury III. I have a few electrical items I'm curious about.

My biggest concern is the ammeter. I read online that with age, these can fail catastrophically (read as: car fire) since they carry the entire load of the alternator through the firewall into the dash. Mine is working at the moment, but I'm curious which wires under the hood run to the ammeter so I can bypass it if necessary. I also read that with ammeters in general (not with Chrysler ones specifically), they can be converted to work as voltmeters instead by adding resistors. Has anyone done this on their Chrysler vehicles? Sounds like a pretty straightforward conversion that could add some piece of mind to an old electrical system.

Next item would be the distributor. I remember growing up lots of people saying Chrysler vehicles ran poorly in the rain. My first car was a Plymouth, and sure enough, it did run poorly when it was raining. I later heard there was a very simple fix for this involving the distributor, but I can't seem to find that fix anywhere online. Does anyone know what I'm talking about? Seems like something I should do to this car while I'm fixing it up.

The old alternator in the car is weak (discharges when under too much load). I bought a remanufactured unit it and it solved my charging problem, but the bearings on the reman unit are already failing (surprise, surprise). I'm going to buy a new alternator instead and found an affordable, American-made one that puts out 95 amps. I assume the original was 60 amps. Any risk in going with the higher amperage? My understanding is it will only generate what the car "asks" for, so it doesn't matter. But then I thought back to the old ammeter; if it has an issue, it may "ask" for more current than what it actually should have. Wouldn't then a higher amp alternator be more likely to cause an electrical fire?

Last thing is very minor, but I noticed there are a couple little lights that shine on the ignition and headlight switch when getting in the car at night. Very cool idea, but they don't seem to work consistently. I'm curious how they work so that I can make them function properly. I'm speculating that they are supposed to come on when the door opens and then stay on for a minute or so after the door is shut.

Opinions or info on any/all of these four items are much appreciated.
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Lots of good info. Thank you to all.

So what I'm thinking is run the bypass from the alternator to the starter relay as stated by moparroy and the linked informational post. Then in the original wiring I'll add a resistor to mimic the '75+ design (as I understand it from the linked informational post). Then I'd keep my working alternator gauge and dodge the fire hazard. Only question would be what what size resistor would be needed? Even if no one knows, seems like it wouldn't be too hard to figure out by trial and error (or even using a potentiometer). For the bypass wire, can I route it through a circuit breaker instead of a fusible link? Easy reset systems are much nicer in the event of future failures.

Anyone have any opinions on WAI Global brand alternators? That's the new 60 amp alternator available on Rock Auto. The company's based in America, but their manufacturing is in China, so certainly not my preferred choice. They're the same price as the new 90 amp alternator I was looking at ($150-$160 range after shipping).

On the distributor, we drilled a small hole in the bottom of the housing to 'vent' the ionized gases or any moisture from inside. A vented distributor cap also works.
The weatherstrip between the cowl & hood is important to keep the distributor dry. Good plug wires with a 'smear' of silicone or dieelctric grease under the terminal boots will add an extra degree of weatherproofing. They also ease the removal of the terminals from the plugs or cap in the future.
Vented distributor cap sounds like a cheap and easy upgrade. I'll also add some dielectric grease to the wires.

There is a time delay relay for lighting important areas for a moment after the dome light goes out. It may be failing. It can come apart for inspection and contact cleaning, etc. if you want to try a Hail Mary on it first. It may be plugged into the fuse block or hanging around the steering column under the dash?
Found the time delay relay. It was just handing freely to the left of the steering column. Opened it up and cleaned it a bit and it seems to be working more consistently now. Quickly opening and shutting the door gives about twenty-five seconds of light; leaving the door open so the relay can heat up longer seems to max it out at sixty-five seconds. These numbers seem like they are what I would expect (before on the occasion when it did work, it would take about four seconds to come on and then only stay on for about six seconds). I did have it stick on the first time I tested it, though, so given how cheap a new one is, I may just replace it so I don't end up with a dead battery.


Took my steering wheel off today because I was having an issue where the car would honk when I turned and it also made a scraping sound as it rotated. I believe I've fixed the horn issue, but I noticed a couple oddities while I had things apart.

There were three wires that were clipped. Everything seems to work, so are these on the harness for an option my car doesn't have, and they just clipped them at the factory because they weren't needed? I'm thinking maybe cruise control, which I don't have.
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I also found a random retaining clip that doesn't slot into anything...not really sure why it's on the steering wheel shaft. Since it wasn't seated in anything, I removed it on the off chance it was causing my random horn honking (though I don't believe it was the cause).
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I have not been able to fix the scraping noise when turning the wheel. It seems it must be coming from further down the column. The steering wheel slides in and out of the column about a quarter of an inch when everything is together (I'm going to double check in the morning, but it didn't look like my loose mystery clip had anything to do with this movement). The scraping only occurs when the wheel is pushed in (which is always while turning since I steer by putting my palm on the face of the wheel).
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That did it. Just wasn't pulling hard enough on the shaft to reveal the grove for the snap ring yesterday. Ring is back, play is gone, scraping is gone, and this would have been what was causing my random honking as well (the back of the blade on the horn ring was nicking things as the wheel spun, causing random honks; I initially fixed it by bending the blade forward a bit, but the steering wheel being a 1/4" too far into the column was the root cause).

Today I went to pull the instrument cluster face off so I could look at the headlight switch (no power to the dash lights when it's on) and so I could remove the clock and radio which are both broken. I got all the screws out, and when I went to pull the face off...the cluster and the controls to the left of it all moved with it. Is this stuff really mounted to the plastic face from the back and not the metal of the dash behind the face? I must be missing something; surely they wouldn't design it that way...

I undid the four silver screws along the bottom, the two on the sides (one left and one right), all the screws that held in the dash lights so that that assembly fell down, and the one screw above the radio hidden behind the dash light assembly. The right half of the cluster face definitely looks like it should come out by itself, but I couldn't get it to separate and was afraid to pull too hard and break it.
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I went ahead and ordered the appropriate fusible link off Amazon (parts store didn't have any, which I found odd).

Can anyone tell me where the blower motor would be located on this car? Mine sounds pretty sickly. I have the AC option, and when I look in the 1972 service manual, they only seem to show the non-AC configuration for the Fury. The blower motor's not out in the open on the firewall like most cars. While looking around, I spotted something that might be it inside the fender, but there's no good way to get a look at it to see if it's a blower motor. Having to remove a fender to replace a blower motor wouldn't make a lot of sense, though...

Scratch that. I found the service information for my system. That thing I saw inside the fender was the blower motor. The service manual says, "The inner fender shield must be removed to service the blower," which I read as the wheel well. Kind of annoying, but at least I know where it is and what needs to come off to replace it.


Also want to add I was able to get the plastic face that goes over the radio and climate controls off. There were two screws on the bottom behind the faux wood bezel attaching it to said bezel. The radio, oddly, could only be removed by sliding it back into the dashboard and then dropping it out the bottom (had two bolts on the front and a bracket on the back holding it in). Wasn't a big deal for me because I have all the ductwork taken out right now, but I'm guessing that would normally interfere with removal. The rest of the instrument cluster face (the left side) is still in place with no obvious way to remove it to access the headlight switch.
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Right, so the fusible link from Amazon showed up and I went to put in the bypass wire today, only to be thoroughly confused.

I was looking for a wire coming out of the wiring bulkhead running to the starter relay, but I cannot find one. There is a beefy black wire running to the wiring bulkhead (I'm assuming this is from the alternator; it has a fusible link right as it runs into the bulkhead), but then there are no other large wires connected to the bulkhead. I was expecting two large wires to run through the bulkhead, one coming from the alternator and one connecting to the starter relay. It kind of looks like someone was already messing with this at some point. A lot of the wires are bundled into black electrical tape, which doesn't seem like something that would be done at the factory.

These pictures aren't the greatest, but here's what I'm looking at. The wire outlined in blue is the only wire going into the bulkhead that looks thick enough to be part of the charging circuit. The terminal outlined in blue (not my car, just a reference image) is where this wire connects. While my bulkhead is different than the diagrams in this thread so far, I believe that is pin 16.
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This electrical tape around many of the wires makes me think someone has meddled with the wiring before me:
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Where is the bypass wire supposed to run? I'm assuming from the lug on the alternator to the top connection on the relay (where the red wire connects in the picture). The middle connection looks to run down to the starter, and my understanding is the two smaller wires on the bottom are for the ignition and neutral safety switch (I'm confident with wires that small they aren't doing any heavy lifting). To be honest, now I'm a little leery of doing anything. If someone else messed with this already and everything is currently working, I'm more inclined to leave well enough alone since I have no idea what they did.
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