Okay it takes A LOT for me to throw my hands up and say "I'm stumped." when working on cars considering I managed a car shop in Rhode Island and specialized in Jaguars with the "Prince of Darkness." (AKA. Lucas.) wiring.

I had driven nothing but Jaguars and old 200 series Volvos for the past few years and loathed current (post 1995.) domestic cars, but I absolutely fell in love with my soon to be brother in law's 74 Valiant.

When I moved out to Vegas, I promised myself I would get a Plymouth Valiant and I scored a '76 slant six with a rebuilt Holley 1Bbl that needs paint and a headliner for a mere $700. And to be completely honest, it's been the most damned reliable vehicle I've ever had and has NEVER failed to START, RUN and DRIVE!

The electrical? Eh not so much. I STUPIDLY left my old Mitchell wiring diagrams from 1963-1988 back in Rhode Island figuring I could just get a Haynes manual and I'd be good, right? WRONG. This stupid manual has absolutely NOTHING for electrical and says "Consult Operator's Manual for wiring information." Lovely...

Well my Valiant has developed this lovely electrical problem where all of the electronics slowly die. In my experience, an alternator that's not charging would be the culprit since if a Voltage Regulator is faulty, the car just stops running. The problem has gotten so severe that I can't even drive my car at night because the headlights are as a dim as a flashlight that has only a few seconds of battery life left and the blinkers and brake lights are inoperable. I tested voltage when I came home and it's charging - somewhat. The battery was down to 4 volts (It's a new battery.) and only charged back up to 8.6 volts. (The catch is there was no load on the alternator.)

I charged up the battery tonight and the car started up, ran and drove great for about 1/6th of a mile when all of the lights started to go dim VERY quickly. I turned the car off and let it sit for a few hours. I just went out there, turned the headlights on - bright. kept the headlights on and put the hazard lights on - fully functional, only a very minor dimness from the headlights, the interior light ? nice and bright.

I'm hesitant to believe it's the alternator because it looks brand new, but then again the battery that I got with the car looked brand new and it was made in 2004...

What's your thoughts? I'm still leaning towards the voltage regulator.

This test is for the later style Dual Field connection alternator, with electronic regulator.

There are 3 wires on the back of the alternator. The heavy "battery" wire, and the 2 "field" wires. The field wires are blue and green. Unplug the green wire from the alternator. Connect a "jumper" wire to that terminal on the alternator. Connect a volt meter to the battery, start the engine, and connect the free end of the "jumper" wire to a good ground. See if the volt meter shows at least 13.5 volts at the battery. If yes, then either the regulator is bad, or you have a wiring problem (possibly a bad ground at the regulator).

If you don't get at least 13.5 volts at the battery. Disconnect the jumper wire. With the engine off, but the key on, see if you have battery voltage at the blue wire on the alternator. If yes, see if you have battery voltage at the terminal on the alternator that had the green wire attached.

If you did not have bat voltage at the blue wire, you have a wiring problem. If you do have bat voltage, at the blue wire, The alternator is bad.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Welcome aboard 76Valiant.

You may want to scrap the useless Haynes manual, and pick up a Factory Service Manual.

Here is a site that has Mopar electrical diagrams for your car.

Recovering prince of darkness follower having owned a 1959 AH Sprite…
Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I've learned to a good way to strike up a conversation with English car owners is to ask them about their electrical systems and let them rant.

A decent fully charged battery ought to let you drive a long time (1-2 hr) even with the headlights on with the alternator disconnected. I suspect that if you start to see the lights dim in 1/6 mi, you've probably got either a big short or a temperature-dependent very high resistance somewhere.

If you've a short, the battery is getting run down quickly; if you've a flaky connection, the connection is heading up and partially blocking the current but the battery is OK. An inexpensive multimeter ($4-10) will let you determine which is the case very quickly.

From my experience, the #1 trouble spot for resistance are the battery clamps &cables; the #2 trouble spot is the bulkhead feedthrough - the 2 pins that go to the ammeter. The latter tend to corrode & overheat.

I've seen alternators short out intermittently due to a loose screws and broken brushes, so even if it doesn't seem shorted sitting still you still want to test it. Mopar alternators of that vintage allow very easy brush changes from the outside.

Also, sometimes batteries develop internal shorts... but then I'd expect it to go dead quickly just sitting there.

Good Luck!

Thanks so much for the advice guys!

I decided to just part ways with the car and sell it...
Hahahaha yeah right...I'm not stupid.

Amazingly the car fired right up this morning with the battery reading only a mere 8 volts. (Think about it, it's like starting up your Mopar with a 9 volt battery...)

Well I knew testing was going to be cumbersome so I charged the battery up until it read 14.2 volts. The car robustly fired up and I could begin testing...Well, there IS current going to the alternator. But the alternator surely is NOT charging. Every load test I did on it, the car died. That's a huge red flag for a faulty alternator.


It kind of got me thinking...I put 2,000 miles on this car just running off the battery. I thought of all of the places I went to, all of the desolate areas I went to with my heat and music blaring and my car never showed signs of trouble until I was 2 miles away from home. That's amazing...It's the way cars SHOULD be. For crying out loud, I could just charge up the battery and STILL drive the 10 miles to get to the parts store. I mean when I changed my battery, I was able to drive it safely to work to buy a new battery - which was 15 miles out of the way. I swear to God every day I find new reasons why I love this car. Its reliability is unbelievably amazing.

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Hi 76valiant, and welcome to the forum.

I worked with english motorcycles with (sob!) Lucas (sob!) 'electrics' for years.

My boss hammered into my scull the one thing to check before ever doing anything else: Check, remove, clean and remount every ground connection. Twice! Then you can start looking for a ground connection you forgot, and THEN you can start looking for all other possibilities. And with Lucas (sob!) they were endless...

But hey, I see the others here steer you onto the same path, so it must have been good advice anyway!

Please tell us what you find!

Olaf.

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Aspenized

Reminds me of a friend I had in the Air Force. He loved Jaguars and owned three...a restored fifty-something...a very clean sixty-something, and one that was a couple of years old at that time in the late 80's.

He came to work one day driving a stock, rough, '48 Ford sedan and I asked him why he was driving that car. He said all three of his Jags had electrical problems and that the Ford was the only car he could get started that morning.

I think I'd really have to love Jags to put up with all the infamous Lucas issues.

It is quite possible & common for Mopar alternators to partially die and/or partially work. I fixed a number of them. J.C.Whitney used to sell rebuild kits I've used that worked pretty well (not all fit all models, so beware), but some reduce low-rpm charging to improve higher-rpm charging.

The only part I've not replaced has been the field winding armature (the stuff that spins); every other part has failed on one or another alt's. The brushes are trivial to replace from the outside; you might want to get new brush insulators too as they sometimes break.

With the special puller ($25-ish at Harbor Freight) it's easy to take the pulley off. The bearings are the next to go, but are universal and not expensive. I use a press to push them in and out easily. The diodes and stator winding get expensive enough that it may be cheaper to just get a rebuilt alternator. Advance Auto and others offer free testing of the alt off the car; sometimes their employees don't know what they're doing; sometimes they do.

I once made the mistake of anti-seizing the screws that held the case together; vibration worked the screws loose and things fell apart. Probably not a good idea there, but I'm a big believer of antiseantiseizeost places that are prone to corrosion.

Well it was just easier and cheaper to buy a remanufactured alternator at autozone. However after replacing it, I was still only getting 12 volts. I disconnected the negative battery cable and there was 11 volts! Wow talk about grounding out! Well the smaller ground wire that runs to the headlight ground was all cracked and mickey moused... I shrugged and replaced that whole ground...What the frack? I'm still getting 11 volts of drainage. I reconnected the ground, shrugged and started the car up. Now I'm getting well over 14 volts and the alternator is definitely charging.

Am I just being a moron and not testing for voltage drain properly? When I had the ground battery cable off, I put the positive end of the voltmeter on a random good ground and the negative end of the voltmeter on the negative battery terminal and I was still getting 11 volts of drain lol...

I know I'm doing something wrong...I just don't remember what it is.

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<img src="http://i49.photobucket.com/albums/f252/sublimeskunk37/WeddingValiant2-1.jpg" border="0" alt="Photobucket">

Time to dump that Lucas VOM…

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

That is not 11 volts of drain. If you put hte volt meter on ground and the other lead on the battery terminal, with the battery cable disconnected, if any electrical is turned on (including the interior light), you will read near battery voltage. You are reading the battery thru the car wireing.
I'm not sure if I can explain it understandably, in writing. I'll let someone else try.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

If you put a voltmeter in series with the ground lead you will get a meaningless reading. You need to use a AMPmeter in series, not voltage. Use a voltmeter across(parellel) to the ground cable to look for a bad cable/ground.

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50 chrysler,54 Plymouth, 64 Valiant conv 4 speed, 66 Valiant V8 wagon, 70 Challenger R/T 440+6 conv 4 speed,80 Colt, 98 Neon ACR,84 Honda V45 Magna
Taking care of 57 300C conv,48 T&C conv. Missing my 67 GTX and 36 Ply coupe

Take a look at my pics below, originally from the thread Gm Hei Module Conversion Troubles.

The voltage at the (low after plenty testing) battery posts, engine not running.

The voltage between the input point to the ballast resistor and ground.

There is a loss in every single attachment point for your wires, only very small numbers, but they add up to quite a loss in a nearly 40 year old wire harness.
Unless you go for a totally original car, it is a good reason to feed all heavy drains, like horns, lights, ignition through relays, and then only use the old wires from the harness as switching input for the relays.

Re: The rotten ground wire for your lights; told you so, think (sob!) Lucas!

Olaf.

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Aspenized

Hahaha yes good ol' Lucas...

I still remember (like it was yesterday.) COMPLETELY rewiring my 1985 Jaguar XJ6....COMPLETELY GUTTING every little wire and re-wiring it the RIGHT way! Until my Valiant, that was the most reliable car I've EVER had.

But it was the alternator that was the fault to everything. My headlights are now very bright, along with my instrument panel.

The only other problem I have electrical-wise is my stupid idiot light for the brakes. The master cylinder is perfect, there's nothing wrong with my brakes...I know it's just a malfunction in the switch and I've tried taking out the bulb, burning out the bulb and when I do that, the instrument panel lights along with the fuel and temperature gauge don't work.

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